tsb: refactor the pure tier onto libavr sugar

The showcase tier now leans on the helpers it fed back instead of reaching under
them: the info block is an avr::flash_table (no raw [[gnu::progmem]]), a page is
filled with spm::fill(addr, span) (no hand-packed lo|hi<<8 loop), and the
WDT-reset bail reads field<"MCUSR","WDRF">::test() (no read() & {}(1).value).

Zero-overhead throughout: .text stays 740 B, byte-identical across generated and
reflect modes, protocol test green. The info block streams through the existing
address-based send_flash rather than a range-for over the flash_table — the
range-for is a distinct loop that cannot share the loader's one flash streamer,
so it would add 14 B for no functional gain.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.clang-format

@@ -1,5 +1,6 @@
 ---
 BasedOnStyle: LLVM
+Standard: Latest
 ColumnLimit: 120
 IndentWidth: 4
 TabWidth: 4

.gitignore

@@ -9,3 +9,8 @@ Debug
 *.eeprom
 *.lss
 *.map
+
+# CMake / clangd
+/build/
+compile_commands.json
+.cache/

.gitmodules

@@ -1,27 +0,0 @@
-[submodule "tsb/io"]
-	path = tsb/io
-	url = git@git.blackmark.me:avr/io.git
-[submodule "tsb/flash"]
-	path = tsb/flash
-	url = git@git.blackmark.me:avr/flash.git
-[submodule "tsb/uart"]
-	path = tsb/uart
-	url = git@git.blackmark.me:avr/uart.git
-[submodule "tsb/type"]
-	path = tsb/type
-	url = git@git.blackmark.me:avr/type.git
-[submodule "stk500v2/type"]
-	path = stk500v2/type
-	url = git@git.blackmark.me:avr/type.git
-[submodule "stk500v2/io"]
-	path = stk500v2/io
-	url = git@git.blackmark.me:avr/io.git
-[submodule "stk500v2/uart"]
-	path = stk500v2/uart
-	url = git@git.blackmark.me:avr/uart.git
-[submodule "stk500v2/flash"]
-	path = stk500v2/flash
-	url = git@git.blackmark.me:avr/flash.git
-[submodule "blink/io"]
-	path = blink/io
-	url = git@git.blackmark.me:avr/io.git

CMakeLists.txt

@@ -0,0 +1,74 @@
+cmake_minimum_required(VERSION 3.28)
+
+project(tsb_libavr LANGUAGES CXX)
+
+# libavr from a local checkout (LIBAVR_ROOT) or the forge; the toolchain file
+# comes from the same checkout via CMakePresets.json.
+include(FetchContent)
+if(NOT LIBAVR_ROOT AND DEFINED ENV{LIBAVR_ROOT})
+	set(LIBAVR_ROOT $ENV{LIBAVR_ROOT})
+endif()
+if(LIBAVR_ROOT)
+	FetchContent_Declare(libavr SOURCE_DIR ${LIBAVR_ROOT})
+else()
+	FetchContent_Declare(libavr GIT_REPOSITORY git@git.blackmark.me:avr/libavr.git GIT_TAG main)
+endif()
+FetchContent_MakeAvailable(libavr)
+
+if(PROJECT_IS_TOP_LEVEL)
+	add_compile_options(-Werror) # warnings are errors for the port's own code
+	enable_testing()
+
+	# The behavioral test drives the real TinySafeBoot wire protocol over a
+	# simavr pty (as the host tools do) and actually flashes the device. The
+	# runner is a host program built at configure time against libsimavr; if it
+	# or Python is missing, only the size tests run.
+	find_program(_host_cc NAMES cc gcc)
+	find_package(Python3 COMPONENTS Interpreter)
+	if(_host_cc AND Python3_FOUND)
+		set(TSB_DEVICE ${CMAKE_BINARY_DIR}/tsb_device)
+		execute_process(
+		    COMMAND ${_host_cc} -O2 -I/usr/include/simavr -I/usr/include/simavr/parts
+		            -o ${TSB_DEVICE} ${CMAKE_CURRENT_SOURCE_DIR}/test/device.c
+		            -lsimavr -lsimavrparts -lelf
+		    RESULT_VARIABLE _dev_res ERROR_VARIABLE _dev_err)
+		if(NOT _dev_res EQUAL 0)
+			message(STATUS "tsb_device not built (${_dev_err}) — protocol tests skipped")
+			unset(TSB_DEVICE)
+		endif()
+	endif()
+endif()
+
+# The TinySafeBoot protocol reimplemented on libavr in three variants that trade
+# clarity for size. Each links into the ATmega328P boot section (BOOTSZ selects
+# its size; BOOTRST vectors a reset to its base) with -nostartfiles — a polled
+# loader has no use for the crt or the vector table. The naked entry sits in
+# .vectors, laid first, and runs. The boot base is FLASHEND+1 minus the section
+# size; the linker section-start and the source's boot_bytes agree.
+#   tsb_asm   — inline-asm variant, the headline: ≤512 B, the 512 B section.
+#   tsb_pure / tsb_tricks — pure-C++ and compiler-trickery variants, larger,
+#                 shown in the 1 KB section (BOOTSZ=10) they fit.
+#
+# add_tsb_variant(<name> <boot-section-bytes>)
+function(add_tsb_variant name bytes)
+	math(EXPR base_dec "32768 - ${bytes}")
+	math(EXPR base_hex "${base_dec}" OUTPUT_FORMAT HEXADECIMAL)
+	add_executable(${name} tsb/${name}.cpp)
+	target_link_libraries(${name} PRIVATE libavr)
+	target_link_options(${name} PRIVATE -nostartfiles -Wl,--section-start=.text=${base_hex})
+	add_custom_command(TARGET ${name} POST_BUILD COMMAND ${CMAKE_SIZE} $<TARGET_FILE:${name}>)
+	if(PROJECT_IS_TOP_LEVEL)
+		add_test(NAME ${name}.size
+		         COMMAND ${CMAKE_COMMAND} -DSIZE_TOOL=${CMAKE_SIZE} -DELF=$<TARGET_FILE:${name}>
+		                 -DLIMIT=${bytes} -P ${CMAKE_CURRENT_SOURCE_DIR}/test/check_size.cmake)
+		if(DEFINED TSB_DEVICE)
+			add_test(NAME ${name}.protocol
+			         COMMAND ${Python3_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/test/tsbtest.py
+			                 ${TSB_DEVICE} $<TARGET_FILE:${name}> ${base_hex})
+		endif()
+	endif()
+endfunction()
+
+add_tsb_variant(tsb_asm 512)
+add_tsb_variant(tsb_pure 1024)
+add_tsb_variant(tsb_tricks 1024)

CMakePresets.json

@@ -0,0 +1,44 @@
+{
+	"version": 8,
+	"configurePresets": [
+		{
+			"name": "base",
+			"hidden": true,
+			"generator": "Ninja",
+			"binaryDir": "${sourceDir}/build/${presetName}",
+			"toolchainFile": "$env{LIBAVR_ROOT}/cmake/avr-toolchain.cmake",
+			"cacheVariables": {
+				"CMAKE_BUILD_TYPE": "Release",
+				"CMAKE_EXPORT_COMPILE_COMMANDS": "ON",
+				"CMAKE_COLOR_DIAGNOSTICS": "ON"
+			}
+		},
+		{
+			"name": "atmega328p-generated",
+			"inherits": "base",
+			"cacheVariables": { "LIBAVR_MCU": "atmega328p", "LIBAVR_REFLECT": "OFF" }
+		},
+		{
+			"name": "atmega328p-reflect",
+			"inherits": "base",
+			"cacheVariables": { "LIBAVR_MCU": "atmega328p", "LIBAVR_REFLECT": "ON" }
+		}
+	],
+	"buildPresets": [
+		{ "name": "atmega328p-generated", "configurePreset": "atmega328p-generated" },
+		{ "name": "atmega328p-reflect", "configurePreset": "atmega328p-reflect" }
+	],
+	"workflowPresets": [
+		{
+			"name": "atmega328p-generated",
+			"steps": [
+				{ "type": "configure", "name": "atmega328p-generated" },
+				{ "type": "build", "name": "atmega328p-generated" },
+				{ "type": "test", "name": "atmega328p-generated" }
+			]
+		}
+	],
+	"testPresets": [
+		{ "name": "atmega328p-generated", "configurePreset": "atmega328p-generated", "output": { "outputOnFailure": true } }
+	]
+}

blink/blink.cppproj

@@ -1,239 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003" ToolsVersion="14.0">
-  <PropertyGroup>
-    <SchemaVersion>2.0</SchemaVersion>
-    <ProjectVersion>7.0</ProjectVersion>
-    <ToolchainName>com.Atmel.AVRGCC8.CPP</ToolchainName>
-    <ProjectGuid>{d887fc8e-ee68-4248-8382-92dbc9a54145}</ProjectGuid>
-    <avrdevice>ATmega328P</avrdevice>
-    <avrdeviceseries>none</avrdeviceseries>
-    <OutputType>Executable</OutputType>
-    <Language>CPP</Language>
-    <OutputFileName>$(MSBuildProjectName)</OutputFileName>
-    <OutputFileExtension>.elf</OutputFileExtension>
-    <OutputDirectory>$(MSBuildProjectDirectory)\$(Configuration)</OutputDirectory>
-    <AssemblyName>blink</AssemblyName>
-    <Name>blink</Name>
-    <RootNamespace>blink</RootNamespace>
-    <ToolchainFlavour>avr-g++-9.1.0</ToolchainFlavour>
-    <KeepTimersRunning>true</KeepTimersRunning>
-    <OverrideVtor>false</OverrideVtor>
-    <CacheFlash>true</CacheFlash>
-    <ProgFlashFromRam>true</ProgFlashFromRam>
-    <RamSnippetAddress>0x20000000</RamSnippetAddress>
-    <UncachedRange />
-    <preserveEEPROM>true</preserveEEPROM>
-    <OverrideVtorValue>exception_table</OverrideVtorValue>
-    <BootSegment>2</BootSegment>
-    <ResetRule>0</ResetRule>
-    <eraseonlaunchrule>0</eraseonlaunchrule>
-    <EraseKey />
-    <avrtool>com.atmel.avrdbg.tool.atmelice</avrtool>
-    <avrtoolserialnumber>J41800099437</avrtoolserialnumber>
-    <avrdeviceexpectedsignature>0x1E950F</avrdeviceexpectedsignature>
-    <com_atmel_avrdbg_tool_stk500>
-      <ToolOptions>
-        <InterfaceProperties>
-          <IspClock>125000</IspClock>
-        </InterfaceProperties>
-        <InterfaceName>ISP</InterfaceName>
-      </ToolOptions>
-      <ToolType>com.atmel.avrdbg.tool.stk500</ToolType>
-      <ToolNumber>
-      </ToolNumber>
-      <ToolName>STK500</ToolName>
-    </com_atmel_avrdbg_tool_stk500>
-    <avrtoolinterface>ISP</avrtoolinterface>
-    <avrtoolinterfaceclock>125000</avrtoolinterfaceclock>
-    <AsfFrameworkConfig>
-      <framework-data xmlns="">
-        <options />
-        <configurations />
-        <files />
-        <documentation help="" />
-        <offline-documentation help="" />
-        <dependencies>
-          <content-extension eid="atmel.asf" uuidref="Atmel.ASF" version="3.47.0" />
-        </dependencies>
-      </framework-data>
-    </AsfFrameworkConfig>
-    <com_atmel_avrdbg_tool_atmelice>
-      <ToolOptions>
-        <InterfaceProperties>
-          <IspClock>125000</IspClock>
-        </InterfaceProperties>
-        <InterfaceName>ISP</InterfaceName>
-      </ToolOptions>
-      <ToolType>com.atmel.avrdbg.tool.atmelice</ToolType>
-      <ToolNumber>J41800099437</ToolNumber>
-      <ToolName>Atmel-ICE</ToolName>
-    </com_atmel_avrdbg_tool_atmelice>
-    <custom>
-      <ToolOptions>
-        <InterfaceProperties>
-          <IspClock>125000</IspClock>
-        </InterfaceProperties>
-        <InterfaceName>
-        </InterfaceName>
-      </ToolOptions>
-      <ToolType>custom</ToolType>
-      <ToolNumber>
-      </ToolNumber>
-      <ToolName>Custom Programming Tool</ToolName>
-    </custom>
-    <com_atmel_avrdbg_tool_simulator>
-      <ToolOptions xmlns="">
-        <InterfaceProperties>
-        </InterfaceProperties>
-        <InterfaceName>
-        </InterfaceName>
-      </ToolOptions>
-      <ToolType xmlns="">com.atmel.avrdbg.tool.simulator</ToolType>
-      <ToolNumber xmlns="">
-      </ToolNumber>
-      <ToolName xmlns="">Simulator</ToolName>
-    </com_atmel_avrdbg_tool_simulator>
-    <AAFDebugger>
-      <AAFDebugFiles>
-      </AAFDebugFiles>
-    </AAFDebugger>
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)' == 'Release' ">
-    <ToolchainSettings>
-      <AvrGccCpp>
-        <avrgcc.common.Device>-mmcu=atmega328p</avrgcc.common.Device>
-        <avrgcc.common.outputfiles.hex>True</avrgcc.common.outputfiles.hex>
-        <avrgcc.common.outputfiles.lss>True</avrgcc.common.outputfiles.lss>
-        <avrgcc.common.outputfiles.eep>True</avrgcc.common.outputfiles.eep>
-        <avrgcc.common.outputfiles.srec>True</avrgcc.common.outputfiles.srec>
-        <avrgcc.common.outputfiles.usersignatures>False</avrgcc.common.outputfiles.usersignatures>
-        <avrgcc.compiler.general.ChangeDefaultCharTypeUnsigned>True</avrgcc.compiler.general.ChangeDefaultCharTypeUnsigned>
-        <avrgcc.compiler.general.ChangeDefaultBitFieldUnsigned>True</avrgcc.compiler.general.ChangeDefaultBitFieldUnsigned>
-        <avrgcc.compiler.symbols.DefSymbols>
-          <ListValues>
-            <Value>NDEBUG</Value>
-          </ListValues>
-        </avrgcc.compiler.symbols.DefSymbols>
-        <avrgcc.compiler.directories.IncludePaths>
-          <ListValues>
-            <Value>%24(PackRepoDir)\Atmel\ATmega_DFP\1.4.346\include</Value>
-          </ListValues>
-        </avrgcc.compiler.directories.IncludePaths>
-        <avrgcc.compiler.optimization.level>Optimize for size (-Os)</avrgcc.compiler.optimization.level>
-        <avrgcc.compiler.optimization.AllocateBytesNeededForEnum>True</avrgcc.compiler.optimization.AllocateBytesNeededForEnum>
-        <avrgcc.compiler.warnings.AllWarnings>True</avrgcc.compiler.warnings.AllWarnings>
-        <avrgcc.compiler.warnings.ExtraWarnings>True</avrgcc.compiler.warnings.ExtraWarnings>
-        <avrgcc.compiler.warnings.Pedantic>True</avrgcc.compiler.warnings.Pedantic>
-        <avrgcc.compiler.miscellaneous.OtherFlags>-fno-threadsafe-statics -std=c11</avrgcc.compiler.miscellaneous.OtherFlags>
-        <avrgcccpp.compiler.general.ChangeDefaultCharTypeUnsigned>True</avrgcccpp.compiler.general.ChangeDefaultCharTypeUnsigned>
-        <avrgcccpp.compiler.general.ChangeDefaultBitFieldUnsigned>True</avrgcccpp.compiler.general.ChangeDefaultBitFieldUnsigned>
-        <avrgcccpp.compiler.symbols.DefSymbols>
-          <ListValues>
-            <Value>NDEBUG</Value>
-          </ListValues>
-        </avrgcccpp.compiler.symbols.DefSymbols>
-        <avrgcccpp.compiler.directories.IncludePaths>
-          <ListValues>
-            <Value>%24(PackRepoDir)\Atmel\ATmega_DFP\1.4.346\include</Value>
-          </ListValues>
-        </avrgcccpp.compiler.directories.IncludePaths>
-        <avrgcccpp.compiler.optimization.level>Optimize for size (-Os)</avrgcccpp.compiler.optimization.level>
-        <avrgcccpp.compiler.optimization.AllocateBytesNeededForEnum>True</avrgcccpp.compiler.optimization.AllocateBytesNeededForEnum>
-        <avrgcccpp.compiler.warnings.AllWarnings>True</avrgcccpp.compiler.warnings.AllWarnings>
-        <avrgcccpp.compiler.warnings.Pedantic>True</avrgcccpp.compiler.warnings.Pedantic>
-        <avrgcccpp.compiler.miscellaneous.OtherFlags>-fno-threadsafe-statics -Wextra -std=c++17</avrgcccpp.compiler.miscellaneous.OtherFlags>
-        <avrgcccpp.linker.libraries.Libraries>
-          <ListValues>
-            <Value>libm</Value>
-          </ListValues>
-        </avrgcccpp.linker.libraries.Libraries>
-        <avrgcccpp.assembler.general.IncludePaths>
-          <ListValues>
-            <Value>%24(PackRepoDir)\Atmel\ATmega_DFP\1.4.346\include</Value>
-          </ListValues>
-        </avrgcccpp.assembler.general.IncludePaths>
-      </AvrGccCpp>
-    </ToolchainSettings>
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)' == 'Debug' ">
-    <ToolchainSettings>
-      <AvrGccCpp>
-        <avrgcc.common.Device>-mmcu=atmega328p</avrgcc.common.Device>
-        <avrgcc.common.outputfiles.hex>True</avrgcc.common.outputfiles.hex>
-        <avrgcc.common.outputfiles.lss>True</avrgcc.common.outputfiles.lss>
-        <avrgcc.common.outputfiles.eep>True</avrgcc.common.outputfiles.eep>
-        <avrgcc.common.outputfiles.srec>True</avrgcc.common.outputfiles.srec>
-        <avrgcc.common.outputfiles.usersignatures>False</avrgcc.common.outputfiles.usersignatures>
-        <avrgcc.compiler.general.ChangeDefaultCharTypeUnsigned>True</avrgcc.compiler.general.ChangeDefaultCharTypeUnsigned>
-        <avrgcc.compiler.general.ChangeDefaultBitFieldUnsigned>True</avrgcc.compiler.general.ChangeDefaultBitFieldUnsigned>
-        <avrgcc.compiler.symbols.DefSymbols>
-          <ListValues>
-            <Value>DEBUG</Value>
-          </ListValues>
-        </avrgcc.compiler.symbols.DefSymbols>
-        <avrgcc.compiler.directories.IncludePaths>
-          <ListValues>
-            <Value>%24(PackRepoDir)\Atmel\ATmega_DFP\1.4.346\include</Value>
-          </ListValues>
-        </avrgcc.compiler.directories.IncludePaths>
-        <avrgcc.compiler.optimization.level>Optimize (-O1)</avrgcc.compiler.optimization.level>
-        <avrgcc.compiler.optimization.AllocateBytesNeededForEnum>True</avrgcc.compiler.optimization.AllocateBytesNeededForEnum>
-        <avrgcc.compiler.optimization.DebugLevel>Maximum (-g3)</avrgcc.compiler.optimization.DebugLevel>
-        <avrgcc.compiler.warnings.AllWarnings>True</avrgcc.compiler.warnings.AllWarnings>
-        <avrgcc.compiler.warnings.ExtraWarnings>True</avrgcc.compiler.warnings.ExtraWarnings>
-        <avrgcc.compiler.warnings.Pedantic>True</avrgcc.compiler.warnings.Pedantic>
-        <avrgcc.compiler.miscellaneous.OtherFlags>-fno-threadsafe-statics -std=c11</avrgcc.compiler.miscellaneous.OtherFlags>
-        <avrgcccpp.compiler.general.ChangeDefaultCharTypeUnsigned>True</avrgcccpp.compiler.general.ChangeDefaultCharTypeUnsigned>
-        <avrgcccpp.compiler.general.ChangeDefaultBitFieldUnsigned>True</avrgcccpp.compiler.general.ChangeDefaultBitFieldUnsigned>
-        <avrgcccpp.compiler.symbols.DefSymbols>
-          <ListValues>
-            <Value>DEBUG</Value>
-          </ListValues>
-        </avrgcccpp.compiler.symbols.DefSymbols>
-        <avrgcccpp.compiler.directories.IncludePaths>
-          <ListValues>
-            <Value>%24(PackRepoDir)\Atmel\ATmega_DFP\1.4.346\include</Value>
-          </ListValues>
-        </avrgcccpp.compiler.directories.IncludePaths>
-        <avrgcccpp.compiler.optimization.level>Optimize (-O1)</avrgcccpp.compiler.optimization.level>
-        <avrgcccpp.compiler.optimization.AllocateBytesNeededForEnum>True</avrgcccpp.compiler.optimization.AllocateBytesNeededForEnum>
-        <avrgcccpp.compiler.optimization.DebugLevel>Maximum (-g3)</avrgcccpp.compiler.optimization.DebugLevel>
-        <avrgcccpp.compiler.warnings.AllWarnings>True</avrgcccpp.compiler.warnings.AllWarnings>
-        <avrgcccpp.compiler.warnings.Pedantic>True</avrgcccpp.compiler.warnings.Pedantic>
-        <avrgcccpp.compiler.miscellaneous.OtherFlags>-fno-threadsafe-statics -Wextra -std=c++17</avrgcccpp.compiler.miscellaneous.OtherFlags>
-        <avrgcccpp.linker.libraries.Libraries>
-          <ListValues>
-            <Value>libm</Value>
-          </ListValues>
-        </avrgcccpp.linker.libraries.Libraries>
-        <avrgcccpp.assembler.general.IncludePaths>
-          <ListValues>
-            <Value>%24(PackRepoDir)\Atmel\ATmega_DFP\1.4.346\include</Value>
-          </ListValues>
-        </avrgcccpp.assembler.general.IncludePaths>
-        <avrgcccpp.assembler.debugging.DebugLevel>Default (-Wa,-g)</avrgcccpp.assembler.debugging.DebugLevel>
-      </AvrGccCpp>
-    </ToolchainSettings>
-  </PropertyGroup>
-  <ItemGroup>
-    <Compile Include="bootloader.cpp">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="bootloader.hpp">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="clock.hpp">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="io\io.hpp">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="main.cpp">
-      <SubType>compile</SubType>
-    </Compile>
-  </ItemGroup>
-  <ItemGroup>
-    <Folder Include="io" />
-  </ItemGroup>
-  <Import Project="$(AVRSTUDIO_EXE_PATH)\\Vs\\Compiler.targets" />
-</Project>

blink/bootloader.cpp

@@ -1,46 +0,0 @@
-#include "bootloader.hpp"
-
-#include <avr/io.h>
-#include <avr/pgmspace.h>
-#include <avr/wdt.h>
-
-namespace {
-
-typedef void (*jmp_fn)() __attribute__((noreturn));
-
-jmp_fn boot = reinterpret_cast<jmp_fn>(0x0000);
-jmp_fn bootloader = reinterpret_cast<jmp_fn>(0x7800 / 2);
-
-} // namespace
-
-bool Bootloader::handleReset()
-{
-	wdt_reset();
-	uint8_t mcuStatus = MCUSR;
-	MCUSR &= ~(1 << WDRF);
-	wdt_disable();
-	return (mcuStatus & (1 << WDRF));
-}
-
-void Bootloader::reset()
-{
-	wdt_enable(WDTO_15MS);
-	while (true)
-		;
-}
-
-bool Bootloader::check()
-{
-	if (pgm_read_byte(reinterpret_cast<uint16_t>(bootloader) * 2) != 0xFF)
-		return true;
-
-	return false;
-}
-
-void Bootloader::call()
-{
-	if (check())
-		bootloader();
-	else
-		boot();
-}

blink/bootloader.hpp

@@ -1,24 +0,0 @@
-#pragma once
-
-class Bootloader {
-  public:
-	template <typename Fn>
-	static inline void init(Fn callback)
-	{
-		if (handleReset()) {
-			callback();
-			call();
-		}
-	}
-
-	static inline void enter()
-	{
-		reset();
-	}
-
-  private:
-	static bool handleReset();
-	static void reset();
-	static bool check();
-	static void call();
-};

blink/clock.hpp

@@ -1,5 +0,0 @@
-#pragma once
-
-//#define F_CPU 18'432'000
-#define F_CPU 16'000'000
-#include <util/delay.h>

blink/main.cpp

@@ -1,30 +0,0 @@
-#include "clock.hpp"
-
-#include "io/io.hpp"
-
-#include "bootloader.hpp"
-
-int main()
-{
-	io::Pin<io::P::B5> ledPin;
-	ledPin.dir(io::Dir::OUT);
-	ledPin = false;
-
-	Bootloader::init([&ledPin]() {
-		for (uint8_t i = 0; i < 10; ++i) {
-			ledPin = true;
-			_delay_ms(50);
-			ledPin = false;
-			_delay_ms(50);
-		}
-	});
-
-	for (uint8_t i = 0; i < 10; ++i) {
-		ledPin.toggle();
-		_delay_ms(1000);
-	}
-
-	Bootloader::enter();
-
-	return 0;
-}

bootloader.atsln

@@ -1,34 +0,0 @@
-
-Microsoft Visual Studio Solution File, Format Version 12.00
-# Atmel Studio Solution File, Format Version 11.00
-VisualStudioVersion = 14.0.23107.0
-MinimumVisualStudioVersion = 10.0.40219.1
-Project("{E66E83B9-2572-4076-B26E-6BE79FF3018A}") = "tsb", "tsb\tsb.cppproj", "{DCE6C7E3-EE26-4D79-826B-08594B9AD897}"
-EndProject
-Project("{E66E83B9-2572-4076-B26E-6BE79FF3018A}") = "stk500v2", "stk500v2\stk500v2.cppproj", "{19798CCE-5D96-40E9-B769-D209715DCE0C}"
-EndProject
-Project("{E66E83B9-2572-4076-B26E-6BE79FF3018A}") = "blink", "blink\blink.cppproj", "{D887FC8E-EE68-4248-8382-92DBC9A54145}"
-EndProject
-Global
-	GlobalSection(SolutionConfigurationPlatforms) = preSolution
-		Debug|AVR = Debug|AVR
-		Release|AVR = Release|AVR
-	EndGlobalSection
-	GlobalSection(ProjectConfigurationPlatforms) = postSolution
-		{DCE6C7E3-EE26-4D79-826B-08594B9AD897}.Debug|AVR.ActiveCfg = Debug|AVR
-		{DCE6C7E3-EE26-4D79-826B-08594B9AD897}.Debug|AVR.Build.0 = Debug|AVR
-		{DCE6C7E3-EE26-4D79-826B-08594B9AD897}.Release|AVR.ActiveCfg = Release|AVR
-		{DCE6C7E3-EE26-4D79-826B-08594B9AD897}.Release|AVR.Build.0 = Release|AVR
-		{19798CCE-5D96-40E9-B769-D209715DCE0C}.Debug|AVR.ActiveCfg = Debug|AVR
-		{19798CCE-5D96-40E9-B769-D209715DCE0C}.Debug|AVR.Build.0 = Debug|AVR
-		{19798CCE-5D96-40E9-B769-D209715DCE0C}.Release|AVR.ActiveCfg = Release|AVR
-		{19798CCE-5D96-40E9-B769-D209715DCE0C}.Release|AVR.Build.0 = Release|AVR
-		{D887FC8E-EE68-4248-8382-92DBC9A54145}.Debug|AVR.ActiveCfg = Debug|AVR
-		{D887FC8E-EE68-4248-8382-92DBC9A54145}.Debug|AVR.Build.0 = Debug|AVR
-		{D887FC8E-EE68-4248-8382-92DBC9A54145}.Release|AVR.ActiveCfg = Release|AVR
-		{D887FC8E-EE68-4248-8382-92DBC9A54145}.Release|AVR.Build.0 = Release|AVR
-	EndGlobalSection
-	GlobalSection(SolutionProperties) = preSolution
-		HideSolutionNode = FALSE
-	EndGlobalSection
-EndGlobal

stk500v2/clock.hpp

@@ -1,5 +0,0 @@
-#pragma once
-
-//#define F_CPU 18'432'000
-#define F_CPU 16'000'000
-#include <util/delay.h>

stk500v2/command.hpp

@@ -1,113 +0,0 @@
-#pragma once
-
-#include <stdint.h>
-
-//////////////////////////////////////////////////////////////////////////
-// STK message constants
-
-static constexpr uint8_t MESSAGE_START = 0x1B; // ASCII ESC
-static constexpr uint8_t TOKEN = 0x0E;
-
-//////////////////////////////////////////////////////////////////////////
-// STK general command constants
-
-static constexpr uint8_t CMD_SIGN_ON = 0x01;
-static constexpr uint8_t CMD_SET_PARAMETER = 0x02;
-static constexpr uint8_t CMD_GET_PARAMETER = 0x03;
-static constexpr uint8_t CMD_SET_DEVICE_PARAMETERS = 0x04;
-static constexpr uint8_t CMD_OSCCAL = 0x05;
-static constexpr uint8_t CMD_LOAD_ADDRESS = 0x06;
-static constexpr uint8_t CMD_FIRMWARE_UPGRADE = 0x07;
-
-//////////////////////////////////////////////////////////////////////////
-// STK ISP command constants
-
-static constexpr uint8_t CMD_ENTER_PROGMODE_ISP = 0x10;
-static constexpr uint8_t CMD_LEAVE_PROGMODE_ISP = 0x11;
-static constexpr uint8_t CMD_CHIP_ERASE_ISP = 0x12;
-static constexpr uint8_t CMD_PROGRAM_FLASH_ISP = 0x13;
-static constexpr uint8_t CMD_READ_FLASH_ISP = 0x14;
-static constexpr uint8_t CMD_PROGRAM_EEPROM_ISP = 0x15;
-static constexpr uint8_t CMD_READ_EEPROM_ISP = 0x16;
-static constexpr uint8_t CMD_PROGRAM_FUSE_ISP = 0x17;
-static constexpr uint8_t CMD_READ_FUSE_ISP = 0x18;
-static constexpr uint8_t CMD_PROGRAM_LOCK_ISP = 0x19;
-static constexpr uint8_t CMD_READ_LOCK_ISP = 0x1A;
-static constexpr uint8_t CMD_READ_SIGNATURE_ISP = 0x1B;
-static constexpr uint8_t CMD_READ_OSCCAL_ISP = 0x1C;
-static constexpr uint8_t CMD_SPI_MULTI = 0x1D;
-
-//////////////////////////////////////////////////////////////////////////
-// STK PP command constants
-
-static constexpr uint8_t CMD_ENTER_PROGMODE_PP = 0x20;
-static constexpr uint8_t CMD_LEAVE_PROGMODE_PP = 0x21;
-static constexpr uint8_t CMD_CHIP_ERASE_PP = 0x22;
-static constexpr uint8_t CMD_PROGRAM_FLASH_PP = 0x23;
-static constexpr uint8_t CMD_READ_FLASH_PP = 0x24;
-static constexpr uint8_t CMD_PROGRAM_EEPROM_PP = 0x25;
-static constexpr uint8_t CMD_READ_EEPROM_PP = 0x26;
-static constexpr uint8_t CMD_PROGRAM_FUSE_PP = 0x27;
-static constexpr uint8_t CMD_READ_FUSE_PP = 0x28;
-static constexpr uint8_t CMD_PROGRAM_LOCK_PP = 0x29;
-static constexpr uint8_t CMD_READ_LOCK_PP = 0x2A;
-static constexpr uint8_t CMD_READ_SIGNATURE_PP = 0x2B;
-static constexpr uint8_t CMD_READ_OSCCAL_PP = 0x2C;
-
-static constexpr uint8_t CMD_SET_CONTROL_STACK = 0x2D;
-
-//////////////////////////////////////////////////////////////////////////
-// STK HVSP command constants
-
-static constexpr uint8_t CMD_ENTER_PROGMODE_HVSP = 0x30;
-static constexpr uint8_t CMD_LEAVE_PROGMODE_HVSP = 0x31;
-static constexpr uint8_t CMD_CHIP_ERASE_HVSP = 0x32;
-static constexpr uint8_t CMD_PROGRAM_FLASH_HVSP = 0x33;
-static constexpr uint8_t CMD_READ_FLASH_HVSP = 0x34;
-static constexpr uint8_t CMD_PROGRAM_EEPROM_HVSP = 0x35;
-static constexpr uint8_t CMD_READ_EEPROM_HVSP = 0x36;
-static constexpr uint8_t CMD_PROGRAM_FUSE_HVSP = 0x37;
-static constexpr uint8_t CMD_READ_FUSE_HVSP = 0x38;
-static constexpr uint8_t CMD_PROGRAM_LOCK_HVSP = 0x39;
-static constexpr uint8_t CMD_READ_LOCK_HVSP = 0x3A;
-static constexpr uint8_t CMD_READ_SIGNATURE_HVSP = 0x3B;
-static constexpr uint8_t CMD_READ_OSCCAL_HVSP = 0x3C;
-
-//////////////////////////////////////////////////////////////////////////
-// STK status constants
-
-// Success
-static constexpr uint8_t STATUS_CMD_OK = 0x00;
-
-// Warnings
-static constexpr uint8_t STATUS_CMD_TOUT = 0x80;
-static constexpr uint8_t STATUS_RDY_BSY_TOUT = 0x81;
-static constexpr uint8_t STATUS_SET_PARAM_MISSING = 0x82;
-
-// Errors
-static constexpr uint8_t STATUS_CMD_FAILED = 0xC0;
-static constexpr uint8_t STATUS_CKSUM_ERROR = 0xC1;
-static constexpr uint8_t STATUS_CMD_UNKNOWN = 0xC9;
-
-//////////////////////////////////////////////////////////////////////////
-// STK parameter constants
-static constexpr uint8_t PARAM_BUILD_NUMBER_LOW = 0x80;
-static constexpr uint8_t PARAM_BUILD_NUMBER_HIGH = 0x81;
-static constexpr uint8_t PARAM_HW_VER = 0x90;
-static constexpr uint8_t PARAM_SW_MAJOR = 0x91;
-static constexpr uint8_t PARAM_SW_MINOR = 0x92;
-static constexpr uint8_t PARAM_VTARGET = 0x94;
-static constexpr uint8_t PARAM_VADJUST = 0x95;
-static constexpr uint8_t PARAM_OSC_PSCALE = 0x96;
-static constexpr uint8_t PARAM_OSC_CMATCH = 0x97;
-static constexpr uint8_t PARAM_SCK_DURATION = 0x98;
-static constexpr uint8_t PARAM_TOPCARD_DETECT = 0x9A;
-static constexpr uint8_t PARAM_STATUS = 0x9C;
-static constexpr uint8_t PARAM_DATA = 0x9D;
-static constexpr uint8_t PARAM_RESET_POLARITY = 0x9E;
-static constexpr uint8_t PARAM_CONTROLLER_INIT = 0x9F;
-
-//////////////////////////////////////////////////////////////////////////
-// STK answer constants
-
-static constexpr uint8_t ANSWER_CKSUM_ERROR = 0xB0;

stk500v2/main.cpp

@@ -1,667 +0,0 @@
-#include "clock.hpp"
-
-#include "stk500v2.hpp"
-
-#include "uart/uart.hpp"
-
-#include <math.h>
-
-#include <avr/boot.h>
-#include <avr/interrupt.h>
-#include <avr/io.h>
-#include <avr/pgmspace.h>
-
-#include "command.hpp"
-
-static constexpr auto TIMEOUT = 5000;
-static constexpr auto BAUD_RATE = 115200;
-
-using uart_interface = uart::Hardware0<uart::Config<BAUD_RATE>, uart::Driven::BLOCKING>;
-uart::Uart<uart_interface> serial;
-
-struct Message {
-	uint8_t start;
-	uint8_t number;
-	uint16_t size;
-	uint8_t token;
-	uint8_t body[275];
-	uint8_t checksum;
-};
-
-static inline bool receiveByte(uint8_t &data, uint16_t &timeout)
-{
-	constexpr auto MICROSECOND = 1000.0 * 1000;
-	constexpr auto SYMBOL_SIZE = 9;
-	constexpr auto BYTE_DELAY_US = (SYMBOL_SIZE * MICROSECOND) / BAUD_RATE;
-	constexpr auto NUM_MS_DELAY_STEPS = static_cast<uint16_t>(round(1000 / BYTE_DELAY_US));
-	uint16_t msDelay = NUM_MS_DELAY_STEPS;
-
-	while (timeout) {
-		if (serial.rxByte(data)) {
-			timeout = TIMEOUT;
-			return true;
-		}
-
-		_delay_us(BYTE_DELAY_US);
-
-		if (--msDelay == 0) {
-			msDelay = NUM_MS_DELAY_STEPS;
-			--timeout;
-		}
-	}
-
-	return false;
-}
-
-static inline uint8_t calcChecksum(const Message &msg)
-{
-	uint8_t checksum = msg.start;
-
-	for (uint16_t i = 1; i < 5 + msg.size; ++i) {
-		checksum ^= *(reinterpret_cast<const uint8_t *>(&msg) + i);
-	}
-
-	return checksum;
-}
-
-static inline bool receiveMessage(Message &msg, uint16_t &timeout)
-{
-	if (!receiveByte(msg.start, timeout) || msg.start != MESSAGE_START)
-		return false;
-	if (!receiveByte(msg.number, timeout))
-		return false;
-	if (!receiveByte(*(reinterpret_cast<uint8_t *>(&msg.size) + 1), timeout))
-		return false;
-	if (!receiveByte(*reinterpret_cast<uint8_t *>(&msg.size), timeout) || msg.size > sizeof(msg.body))
-		return false;
-	if (!receiveByte(msg.token, timeout) || msg.token != TOKEN)
-		return false;
-	for (uint16_t i = 0; i < msg.size; ++i) {
-		if (!receiveByte(msg.body[i], timeout))
-			return false;
-	}
-	if (!receiveByte(msg.checksum, timeout) || msg.checksum != calcChecksum(msg))
-		return false;
-
-	return true;
-}
-
-static inline void transmitMessage(const Message &msg)
-{
-	serial.txByte(msg.start);
-	serial.txByte(msg.number);
-	serial.txByte(msg.size >> 8);
-	serial.txByte(msg.size & 0xFF);
-	serial.txByte(msg.token);
-	for (uint16_t i = 0; i < msg.size; ++i)
-		serial.txByte(msg.body[i]);
-	serial.txByte(msg.checksum);
-}
-
-static inline bool isSignOn(const Message &msg)
-{
-	if (msg.size == 1 && msg.body[0] == CMD_SIGN_ON)
-		return true;
-	return false;
-}
-
-static inline bool isGetParameter(const Message &msg)
-{
-	if (msg.size == 2 && msg.body[0] == CMD_GET_PARAMETER)
-		return true;
-	return false;
-}
-
-static inline bool isSetParameter(const Message &msg)
-{
-	if (msg.size == 3 && msg.body[0] == CMD_SET_PARAMETER)
-		return true;
-	return false;
-}
-
-static inline bool isEnterProgmodeIsp(const Message &msg)
-{
-	if (msg.size == 12 && msg.body[0] == CMD_ENTER_PROGMODE_ISP)
-		return true;
-	return false;
-}
-
-static inline bool isReadSignatureIsp(const Message &msg)
-{
-	if (msg.size == 6 && msg.body[0] == CMD_READ_SIGNATURE_ISP)
-		return true;
-	return false;
-}
-
-static inline bool isReadFuseIsp(const Message &msg)
-{
-	if (msg.size == 6 && msg.body[0] == CMD_READ_FUSE_ISP)
-		return true;
-	return false;
-}
-
-static inline bool isReadLockIsp(const Message &msg)
-{
-	if (msg.size == 6 && msg.body[0] == CMD_READ_LOCK_ISP)
-		return true;
-	return false;
-}
-
-static inline bool isLoadAddress(const Message &msg)
-{
-	if (msg.size == 5 && msg.body[0] == CMD_LOAD_ADDRESS)
-		return true;
-	return false;
-}
-
-static inline bool isReadFlashIsp(const Message &msg)
-{
-	if (msg.size == 4 && msg.body[0] == CMD_READ_FLASH_ISP)
-		return true;
-	return false;
-}
-
-static inline bool isReadEepromIsp(const Message &msg)
-{
-	if (msg.size == 4 && msg.body[0] == CMD_READ_EEPROM_ISP)
-		return true;
-	return false;
-}
-
-static inline bool isChipEraseIsp(const Message &msg)
-{
-	if (msg.size == 7 && msg.body[0] == CMD_CHIP_ERASE_ISP)
-		return true;
-	return false;
-}
-
-static inline bool isProgramFlashIsp(const Message &msg)
-{
-	if (msg.body[0] == CMD_PROGRAM_FLASH_ISP) {
-		const auto dataSize = static_cast<uint16_t>(msg.body[1]) << 8 | msg.body[2];
-		if (msg.size == (dataSize + 10) && dataSize == SPM_PAGESIZE)
-			return true;
-	}
-	return false;
-}
-
-static inline bool isProgramEepromIsp(const Message &msg)
-{
-	if (msg.body[0] == CMD_PROGRAM_EEPROM_ISP) {
-		if (msg.size == (static_cast<uint16_t>(msg.body[1]) << 8 | msg.body[2]) + 10)
-			return true;
-	}
-
-	return false;
-}
-
-static inline bool isLeaveProgmodeIsp(const Message &msg)
-{
-	if (msg.size == 3 && msg.body[0] == CMD_LEAVE_PROGMODE_ISP)
-		return true;
-	return false;
-}
-
-static inline void formatSignOnAnswer(Message &msg)
-{
-	msg.size = 3 + 8;
-	msg.body[1] = STATUS_CMD_OK;
-	msg.body[2] = 8;
-	msg.body[3] = 'S';
-	msg.body[4] = 'T';
-	msg.body[5] = 'K';
-	msg.body[6] = '5';
-	msg.body[7] = '0';
-	msg.body[8] = '0';
-	msg.body[9] = '_';
-	msg.body[10] = '2';
-	msg.checksum = calcChecksum(msg);
-}
-
-static inline void formatGetParameterAnswer(Message &msg)
-{
-	msg.size = 3;
-
-	if (msg.body[1] == PARAM_HW_VER) {
-		msg.body[2] = 1;
-	} else if (msg.body[1] == PARAM_SW_MAJOR) {
-		msg.body[2] = 0x02;
-	} else if (msg.body[1] == PARAM_SW_MINOR) {
-		msg.body[2] = 0x0a;
-	} else if (msg.body[1] == PARAM_SCK_DURATION) {
-		msg.body[2] = 2;
-	} else if (msg.body[1] == PARAM_VADJUST) {
-		msg.body[2] = 25;
-	} else if (msg.body[1] == PARAM_VTARGET) {
-		msg.body[2] = 49;
-	} else if (msg.body[1] == PARAM_OSC_PSCALE) {
-		msg.body[2] = 2;
-	} else if (msg.body[1] == PARAM_OSC_CMATCH) {
-		msg.body[2] = 127;
-	} else if (msg.body[1] == PARAM_TOPCARD_DETECT) {
-		msg.body[2] = 0xFF;
-	} else {
-		msg.size = 2;
-	}
-
-	if (msg.size == 2) {
-		msg.body[1] = STATUS_CMD_FAILED;
-	} else {
-		msg.body[1] = STATUS_CMD_OK;
-	}
-
-	msg.checksum = calcChecksum(msg);
-}
-
-static inline void formatSetParameterAnswer(Message &msg)
-{
-	msg.size = 2;
-	msg.body[1] = STATUS_CMD_OK;
-
-	msg.checksum = calcChecksum(msg);
-}
-
-static inline void formatEnterProgmodeIspAnswer(Message &msg)
-{
-	msg.size = 2;
-	msg.body[1] = STATUS_CMD_OK;
-
-	msg.checksum = calcChecksum(msg);
-}
-
-static inline void formatReadSignatureIspAnswer(Message &msg)
-{
-	msg.size = 4;
-	msg.body[2] = boot_signature_byte_get(msg.body[4] * 2);
-	msg.body[1] = STATUS_CMD_OK;
-	msg.body[3] = STATUS_CMD_OK;
-
-	msg.checksum = calcChecksum(msg);
-}
-
-static inline void formatReadFuseIspAnswer(Message &msg)
-{
-	constexpr auto READ_LOW_FUSE_BITS = 0x0050;
-	constexpr auto READ_HIGH_FUSE_BITS = 0x0858;
-	constexpr auto READ_EXTENDED_FUSE_BITS = 0x0850;
-
-	msg.size = 4;
-
-	if (*reinterpret_cast<uint16_t *>(msg.body + 2) == READ_EXTENDED_FUSE_BITS) {
-		msg.body[2] = boot_lock_fuse_bits_get(GET_EXTENDED_FUSE_BITS);
-	}
-	if (*reinterpret_cast<uint16_t *>(msg.body + 2) == READ_HIGH_FUSE_BITS) {
-		msg.body[2] = boot_lock_fuse_bits_get(GET_HIGH_FUSE_BITS);
-	}
-	if (*reinterpret_cast<uint16_t *>(msg.body + 2) == READ_LOW_FUSE_BITS) {
-		msg.body[2] = boot_lock_fuse_bits_get(GET_LOW_FUSE_BITS);
-	}
-
-	msg.body[1] = STATUS_CMD_OK;
-	msg.body[3] = STATUS_CMD_OK;
-
-	msg.checksum = calcChecksum(msg);
-}
-
-static inline void formatReadLockIspAnswer(Message &msg)
-{
-	msg.size = 4;
-	msg.body[2] = boot_lock_fuse_bits_get(GET_LOCK_BITS);
-	msg.body[1] = STATUS_CMD_OK;
-	msg.body[3] = STATUS_CMD_OK;
-
-	msg.checksum = calcChecksum(msg);
-}
-
-static inline void formatLoadAddressAnswer(Message &msg)
-{
-	msg.size = 2;
-	msg.body[1] = STATUS_CMD_OK;
-
-	msg.checksum = calcChecksum(msg);
-}
-
-static inline void formatReadFlashIspAnswer(Message &msg, uint32_t &addr)
-{
-	const uint16_t byteAddress = 2 * addr;
-	const uint16_t numBytes = static_cast<uint16_t>(msg.body[1]) << 8 | msg.body[2];
-	msg.size = 3 + numBytes;
-	msg.body[1] = STATUS_CMD_OK;
-	for (uint16_t i = 0; i < numBytes; ++i) {
-		msg.body[i + 2] = pgm_read_byte(static_cast<uint16_t>(byteAddress + i));
-	}
-	const auto numWords = numBytes / 2;
-	addr += numWords;
-	msg.body[numBytes + 2] = STATUS_CMD_OK;
-
-	msg.checksum = calcChecksum(msg);
-}
-
-namespace {
-
-bool isEepromReady()
-{
-	return (EECR & (1 << EEPE)) ? false : true;
-}
-
-void waitEepromReady()
-{
-	while (!isEepromReady())
-		;
-}
-
-uint8_t readEepromByte(const uint8_t *addr)
-{
-	EEAR = reinterpret_cast<uint16_t>(addr);
-	EECR |= (1 << EERE);
-	return EEDR;
-}
-
-void writeEepromByte(uint8_t *addr, uint8_t value)
-{
-	EECR = 0;
-	EEAR = reinterpret_cast<uint16_t>(addr);
-	EEDR = value;
-	EECR |= (1 << EEMPE);
-	EECR |= (1 << EEPE);
-}
-
-//////////////////////////////////////////////////////////////////////////
-
-void writeFlashPage(uint32_t pageAddress, const uint8_t *data)
-{
-	boot_page_erase(pageAddress);
-	boot_spm_busy_wait();
-
-	for (uint16_t i = 0; i < SPM_PAGESIZE; i += 2) {
-		uint16_t dataWord = *data++;
-		dataWord |= (*data++) << 8;
-		boot_page_fill(pageAddress + i, dataWord);
-	}
-
-	boot_page_write(pageAddress);
-	boot_spm_busy_wait();
-	boot_rww_enable();
-}
-
-} // namespace
-
-static inline uint16_t getBootloaderSize()
-{
-	const auto highFuse = boot_lock_fuse_bits_get(GET_HIGH_FUSE_BITS);
-	constexpr auto BOOTSZ0 = 1;
-	constexpr auto BOOTSZ1 = 2;
-
-	if (highFuse & (1 << BOOTSZ1) && highFuse & (1 << BOOTSZ0))
-		return 256 * 2;
-	else if (highFuse & (1 << BOOTSZ1))
-		return 512 * 2;
-	else if (highFuse & (1 << BOOTSZ0))
-		return 1024 * 2;
-	return 2048 * 2;
-}
-
-static inline uint32_t getFlashSize()
-{
-	const auto bootloaderSize = getBootloaderSize();
-	return (FLASHEND - bootloaderSize + 1);
-}
-
-static inline void performChipErase(uint16_t flashStartAddress = 0x0000)
-{
-	constexpr auto getEepromEraseFuseBit = []() -> bool {
-		constexpr auto EESAVE = 3;
-		return boot_lock_fuse_bits_get(GET_HIGH_FUSE_BITS) & (1 << EESAVE);
-	};
-
-	constexpr auto eraseFlash = [](const uint16_t &flashStartAddress) {
-		const auto flashSize = getFlashSize();
-		const auto byteAddress = 2 * flashStartAddress;
-		for (uint16_t i = byteAddress; i < flashSize; i += SPM_PAGESIZE) {
-			boot_page_erase(i);
-			boot_spm_busy_wait();
-		}
-		boot_rww_enable();
-	};
-
-	constexpr auto eraseEeprom = [getEepromEraseFuseBit]() {
-		const auto eraseEeprom = getEepromEraseFuseBit();
-		if (eraseEeprom) {
-			constexpr auto EEPROM_SIZE = E2END + 1;
-			for (uint16_t i = 0; i < EEPROM_SIZE; ++i) {
-				writeEepromByte(reinterpret_cast<uint8_t *>(i), 0xFF);
-				waitEepromReady();
-			}
-		}
-	};
-
-	eraseFlash(flashStartAddress);
-	eraseEeprom();
-}
-
-static inline void formatChipEraseIspAnswer(Message &msg)
-{
-	msg.size = 2;
-	msg.body[1] = STATUS_CMD_OK;
-
-	msg.checksum = calcChecksum(msg);
-}
-
-static inline void formatReadEepromIspAnswer(Message &msg, uint32_t &addr)
-{
-	const uint16_t numBytes = static_cast<uint16_t>(msg.body[1]) << 8 | msg.body[2];
-	msg.size = 3 + numBytes;
-	msg.body[1] = STATUS_CMD_OK;
-	for (uint16_t i = 0; i < numBytes; ++i) {
-		msg.body[i + 2] = readEepromByte(reinterpret_cast<const uint8_t *>(addr + i));
-	}
-	addr += numBytes;
-	msg.body[numBytes + 2] = STATUS_CMD_OK;
-
-	msg.checksum = calcChecksum(msg);
-}
-
-static inline void formatProgramFlashIspAnswer(Message &msg, uint32_t &addr)
-{
-	const auto byteAddress = 2 * addr;
-	if (byteAddress < getFlashSize())
-		writeFlashPage(byteAddress, msg.body + 10);
-	const uint16_t numBytes = static_cast<uint16_t>(msg.body[1]) << 8 | msg.body[2];
-	const auto numWords = numBytes / 2;
-	addr += numWords;
-
-	msg.size = 2;
-	msg.body[1] = STATUS_CMD_OK;
-
-	msg.checksum = calcChecksum(msg);
-}
-
-static inline void formatProgramEepromIspAnswer(Message &msg, uint32_t &addr)
-{
-	const uint16_t numBytes = static_cast<uint16_t>(msg.body[1]) << 8 | msg.body[2];
-	for (uint16_t i = 0; i < numBytes; ++i) {
-		writeEepromByte(reinterpret_cast<uint8_t *>(addr + i), msg.body[10 + i]);
-		waitEepromReady();
-	}
-	addr += numBytes;
-	msg.size = 2;
-	msg.body[1] = STATUS_CMD_OK;
-
-	msg.checksum = calcChecksum(msg);
-}
-
-static inline void formatLeaveProgmodeIspAnswer(Message &msg)
-{
-	msg.size = 2;
-	msg.body[1] = STATUS_CMD_OK;
-
-	msg.checksum = calcChecksum(msg);
-}
-
-static inline void formatErrorAnswer(Message &msg)
-{
-	msg.start = MESSAGE_START;
-	msg.size = 1;
-	msg.token = TOKEN;
-	msg.body[0] = STATUS_CMD_UNKNOWN;
-	msg.checksum = calcChecksum(msg);
-}
-
-enum class ChipEraseState {
-	NONE = 0,
-	REQUEST = (1 << 1),
-	RESPONSE = (1 << 2),
-	PERFORM = REQUEST | RESPONSE,
-	PROGRAM = (1 << 3),
-	FINISH = REQUEST | RESPONSE | PROGRAM,
-};
-
-constexpr ChipEraseState operator|(const ChipEraseState &self, const ChipEraseState &other)
-{
-	return static_cast<ChipEraseState>(static_cast<uint8_t>(self) | static_cast<uint8_t>(other));
-}
-
-constexpr ChipEraseState &operator|=(ChipEraseState &self, const ChipEraseState &other)
-{
-	self = self | other;
-	return self;
-}
-
-static inline void handleMessage(Message &msg, uint32_t &addr, uint16_t &finishEraseAddress,
-                                 ChipEraseState &chipEraseFlag)
-{
-	if (isSignOn(msg))
-		formatSignOnAnswer(msg);
-	else if (isGetParameter(msg))
-		formatGetParameterAnswer(msg);
-	else if (isSetParameter(msg))
-		formatSetParameterAnswer(msg);
-	else if (isEnterProgmodeIsp(msg))
-		formatEnterProgmodeIspAnswer(msg);
-	else if (isReadSignatureIsp(msg))
-		formatReadSignatureIspAnswer(msg);
-	else if (isReadFuseIsp(msg))
-		formatReadFuseIspAnswer(msg);
-	else if (isReadLockIsp(msg))
-		formatReadLockIspAnswer(msg);
-	else if (isLoadAddress(msg)) {
-		addr = msg.body[1];
-		addr = (addr << 8) | msg.body[2];
-		addr = (addr << 8) | msg.body[3];
-		addr = (addr << 8) | msg.body[4];
-		formatLoadAddressAnswer(msg);
-	} else if (isReadFlashIsp(msg))
-		formatReadFlashIspAnswer(msg, addr);
-	else if (isReadEepromIsp(msg))
-		formatReadEepromIspAnswer(msg, addr);
-	else if (isChipEraseIsp(msg)) {
-		chipEraseFlag |= ChipEraseState::REQUEST;
-		formatChipEraseIspAnswer(msg);
-	} else if (isProgramFlashIsp(msg)) {
-		chipEraseFlag |= ChipEraseState::PROGRAM;
-		formatProgramFlashIspAnswer(msg, addr);
-		finishEraseAddress = addr;
-	} else if (isProgramEepromIsp(msg))
-		formatProgramEepromIspAnswer(msg, addr);
-	else if (isLeaveProgmodeIsp(msg)) {
-		chipEraseFlag |= ChipEraseState::RESPONSE;
-		formatLeaveProgmodeIspAnswer(msg);
-	} else
-		formatErrorAnswer(msg);
-
-	transmitMessage(msg);
-}
-
-static inline void interfaceTest()
-{
-	constexpr auto onSignOn = []() {};
-	constexpr auto onSetParam = []() {};
-	constexpr auto onGetParam = [](stk500v2::Param param, uint8_t &result) {
-		using stk500v2::Param;
-
-		switch (param) {
-		case Param::HW_VER:
-			result = 1;
-			break;
-		case Param::SW_MAJOR:
-			result = 2;
-			break;
-		case Param::SW_MINOR:
-			result = 10;
-			break;
-		case Param::SCK_DURATION:
-			result = 2;
-			break;
-		case Param::VADJUST:
-			result = 25;
-			break;
-		case Param::VTARGET:
-			result = 49;
-			break;
-		case Param::OSC_PSCALE:
-			result = 2;
-			break;
-		case Param::OSC_CMATCH:
-			result = 127;
-			break;
-		case Param::TOPCARD_DETECT:
-			result = 0xFF;
-			break;
-		default:
-			return false;
-		}
-
-		return true;
-	};
-
-	constexpr auto callbacks = stk500v2::Callbacks<onSignOn, onSetParam, onGetParam>();
-
-	stk500v2::Stk500v2<uart_interface, TIMEOUT, callbacks> stk500;
-	stk500.init();
-
-	while (stk500.callback())
-		;
-}
-
-int main()
-{
-	/*interfaceTest();
-	return 0;*/
-
-	serial.init();
-
-	Message msg;
-	uint32_t addr = 0x0000;
-	uint16_t finishEraseAddress = 0x0000;
-	ChipEraseState chipEraseFlag = ChipEraseState::NONE;
-	uint16_t timeout = TIMEOUT;
-
-	while (true) {
-		if (receiveMessage(msg, timeout)) {
-			handleMessage(msg, addr, finishEraseAddress, chipEraseFlag);
-		}
-
-		if (timeout == 0) {
-			if (chipEraseFlag == ChipEraseState::PERFORM) {
-				performChipErase();
-				chipEraseFlag = ChipEraseState::NONE;
-			} else if (chipEraseFlag == ChipEraseState::FINISH) {
-				performChipErase(finishEraseAddress);
-				chipEraseFlag = ChipEraseState::NONE;
-			}
-
-			asm volatile("jmp 0x0000");
-		}
-	}
-
-	return 0;
-}
-
-void startup() __attribute__((naked, section(".vectors")));
-void startup()
-{
-	asm volatile("clr __zero_reg__");
-	SP = RAMEND;
-	SREG = 0;
-	asm volatile("jmp main");
-}

stk500v2/stk500v2.cppproj

@@ -1,275 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003" ToolsVersion="14.0">
-  <PropertyGroup>
-    <SchemaVersion>2.0</SchemaVersion>
-    <ProjectVersion>7.0</ProjectVersion>
-    <ToolchainName>com.Atmel.AVRGCC8.CPP</ToolchainName>
-    <ProjectGuid>{19798cce-5d96-40e9-b769-d209715dce0c}</ProjectGuid>
-    <avrdevice>ATmega328P</avrdevice>
-    <avrdeviceseries>none</avrdeviceseries>
-    <OutputType>Executable</OutputType>
-    <Language>CPP</Language>
-    <OutputFileName>$(MSBuildProjectName)</OutputFileName>
-    <OutputFileExtension>.elf</OutputFileExtension>
-    <OutputDirectory>$(MSBuildProjectDirectory)\$(Configuration)</OutputDirectory>
-    <AssemblyName>stk500v2</AssemblyName>
-    <Name>stk500v2</Name>
-    <RootNamespace>stk500v2</RootNamespace>
-    <ToolchainFlavour>avr-g++-10.0.1</ToolchainFlavour>
-    <KeepTimersRunning>true</KeepTimersRunning>
-    <OverrideVtor>false</OverrideVtor>
-    <CacheFlash>true</CacheFlash>
-    <ProgFlashFromRam>true</ProgFlashFromRam>
-    <RamSnippetAddress>0x20000000</RamSnippetAddress>
-    <UncachedRange />
-    <preserveEEPROM>true</preserveEEPROM>
-    <OverrideVtorValue>exception_table</OverrideVtorValue>
-    <BootSegment>2</BootSegment>
-    <ResetRule>0</ResetRule>
-    <eraseonlaunchrule>0</eraseonlaunchrule>
-    <EraseKey />
-    <avrtool>com.atmel.avrdbg.tool.atmelice</avrtool>
-    <avrtoolserialnumber>J41800099437</avrtoolserialnumber>
-    <avrdeviceexpectedsignature>0x1E950F</avrdeviceexpectedsignature>
-    <com_atmel_avrdbg_tool_stk500>
-      <ToolOptions>
-        <InterfaceProperties>
-          <IspClock>125000</IspClock>
-        </InterfaceProperties>
-        <InterfaceName>ISP</InterfaceName>
-      </ToolOptions>
-      <ToolType>com.atmel.avrdbg.tool.stk500</ToolType>
-      <ToolNumber>
-      </ToolNumber>
-      <ToolName>STK500</ToolName>
-    </com_atmel_avrdbg_tool_stk500>
-    <avrtoolinterface>ISP</avrtoolinterface>
-    <avrtoolinterfaceclock>125000</avrtoolinterfaceclock>
-    <AsfFrameworkConfig>
-      <framework-data xmlns="">
-        <options />
-        <configurations />
-        <files />
-        <documentation help="" />
-        <offline-documentation help="" />
-        <dependencies>
-          <content-extension eid="atmel.asf" uuidref="Atmel.ASF" version="3.47.0" />
-        </dependencies>
-      </framework-data>
-    </AsfFrameworkConfig>
-    <com_atmel_avrdbg_tool_atmelice>
-      <ToolOptions>
-        <InterfaceProperties>
-          <IspClock>125000</IspClock>
-        </InterfaceProperties>
-        <InterfaceName>ISP</InterfaceName>
-      </ToolOptions>
-      <ToolType>com.atmel.avrdbg.tool.atmelice</ToolType>
-      <ToolNumber>J41800099437</ToolNumber>
-      <ToolName>Atmel-ICE</ToolName>
-    </com_atmel_avrdbg_tool_atmelice>
-    <custom>
-      <ToolOptions>
-        <InterfaceProperties>
-          <IspClock>125000</IspClock>
-        </InterfaceProperties>
-        <InterfaceName>
-        </InterfaceName>
-      </ToolOptions>
-      <ToolType>custom</ToolType>
-      <ToolNumber>
-      </ToolNumber>
-      <ToolName>Custom Programming Tool</ToolName>
-    </custom>
-    <com_atmel_avrdbg_tool_simulator>
-      <ToolOptions xmlns="">
-        <InterfaceProperties>
-        </InterfaceProperties>
-        <InterfaceName>
-        </InterfaceName>
-      </ToolOptions>
-      <ToolType xmlns="">com.atmel.avrdbg.tool.simulator</ToolType>
-      <ToolNumber xmlns="">
-      </ToolNumber>
-      <ToolName xmlns="">Simulator</ToolName>
-    </com_atmel_avrdbg_tool_simulator>
-    <AAFDebugger>
-      <AAFDebugFiles>
-      </AAFDebugFiles>
-    </AAFDebugger>
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)' == 'Release' ">
-    <ToolchainSettings>
-      <AvrGccCpp>
-        <avrgcc.common.Device>-mmcu=atmega328p</avrgcc.common.Device>
-        <avrgcc.common.outputfiles.hex>True</avrgcc.common.outputfiles.hex>
-        <avrgcc.common.outputfiles.lss>True</avrgcc.common.outputfiles.lss>
-        <avrgcc.common.outputfiles.eep>True</avrgcc.common.outputfiles.eep>
-        <avrgcc.common.outputfiles.srec>True</avrgcc.common.outputfiles.srec>
-        <avrgcc.common.outputfiles.usersignatures>False</avrgcc.common.outputfiles.usersignatures>
-        <avrgcc.compiler.general.ChangeDefaultCharTypeUnsigned>True</avrgcc.compiler.general.ChangeDefaultCharTypeUnsigned>
-        <avrgcc.compiler.general.ChangeDefaultBitFieldUnsigned>True</avrgcc.compiler.general.ChangeDefaultBitFieldUnsigned>
-        <avrgcc.compiler.symbols.DefSymbols>
-          <ListValues>
-            <Value>NDEBUG</Value>
-          </ListValues>
-        </avrgcc.compiler.symbols.DefSymbols>
-        <avrgcc.compiler.directories.IncludePaths>
-          <ListValues>
-            <Value>%24(PackRepoDir)\Atmel\ATmega_DFP\1.4.346\include</Value>
-          </ListValues>
-        </avrgcc.compiler.directories.IncludePaths>
-        <avrgcc.compiler.optimization.level>Optimize for size (-Os)</avrgcc.compiler.optimization.level>
-        <avrgcc.compiler.optimization.AllocateBytesNeededForEnum>True</avrgcc.compiler.optimization.AllocateBytesNeededForEnum>
-        <avrgcc.compiler.warnings.AllWarnings>True</avrgcc.compiler.warnings.AllWarnings>
-        <avrgcc.compiler.warnings.ExtraWarnings>True</avrgcc.compiler.warnings.ExtraWarnings>
-        <avrgcc.compiler.warnings.Pedantic>True</avrgcc.compiler.warnings.Pedantic>
-        <avrgcc.compiler.miscellaneous.OtherFlags>-fno-threadsafe-statics -std=c11</avrgcc.compiler.miscellaneous.OtherFlags>
-        <avrgcccpp.compiler.general.ChangeDefaultCharTypeUnsigned>True</avrgcccpp.compiler.general.ChangeDefaultCharTypeUnsigned>
-        <avrgcccpp.compiler.general.ChangeDefaultBitFieldUnsigned>True</avrgcccpp.compiler.general.ChangeDefaultBitFieldUnsigned>
-        <avrgcccpp.compiler.symbols.DefSymbols>
-          <ListValues>
-            <Value>NDEBUG</Value>
-          </ListValues>
-        </avrgcccpp.compiler.symbols.DefSymbols>
-        <avrgcccpp.compiler.directories.IncludePaths>
-          <ListValues>
-            <Value>%24(PackRepoDir)\Atmel\ATmega_DFP\1.4.346\include</Value>
-          </ListValues>
-        </avrgcccpp.compiler.directories.IncludePaths>
-        <avrgcccpp.compiler.optimization.level>Optimize for size (-Os)</avrgcccpp.compiler.optimization.level>
-        <avrgcccpp.compiler.optimization.AllocateBytesNeededForEnum>True</avrgcccpp.compiler.optimization.AllocateBytesNeededForEnum>
-        <avrgcccpp.compiler.warnings.AllWarnings>True</avrgcccpp.compiler.warnings.AllWarnings>
-        <avrgcccpp.compiler.warnings.Pedantic>True</avrgcccpp.compiler.warnings.Pedantic>
-        <avrgcccpp.compiler.miscellaneous.OtherFlags>-fno-threadsafe-statics -Wextra -std=c++20</avrgcccpp.compiler.miscellaneous.OtherFlags>
-        <avrgcccpp.linker.general.NoStartupOrDefaultLibs>True</avrgcccpp.linker.general.NoStartupOrDefaultLibs>
-        <avrgcccpp.linker.libraries.Libraries>
-          <ListValues>
-            <Value>libm</Value>
-          </ListValues>
-        </avrgcccpp.linker.libraries.Libraries>
-        <avrgcccpp.linker.memorysettings.Flash>
-          <ListValues>
-            <Value>.text=0x3C00</Value>
-          </ListValues>
-        </avrgcccpp.linker.memorysettings.Flash>
-        <avrgcccpp.assembler.general.IncludePaths>
-          <ListValues>
-            <Value>%24(PackRepoDir)\Atmel\ATmega_DFP\1.4.346\include</Value>
-          </ListValues>
-        </avrgcccpp.assembler.general.IncludePaths>
-      </AvrGccCpp>
-    </ToolchainSettings>
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)' == 'Debug' ">
-    <ToolchainSettings>
-      <AvrGccCpp>
-        <avrgcc.common.Device>-mmcu=atmega328p</avrgcc.common.Device>
-        <avrgcc.common.outputfiles.hex>True</avrgcc.common.outputfiles.hex>
-        <avrgcc.common.outputfiles.lss>True</avrgcc.common.outputfiles.lss>
-        <avrgcc.common.outputfiles.eep>True</avrgcc.common.outputfiles.eep>
-        <avrgcc.common.outputfiles.srec>True</avrgcc.common.outputfiles.srec>
-        <avrgcc.common.outputfiles.usersignatures>False</avrgcc.common.outputfiles.usersignatures>
-        <avrgcc.compiler.general.ChangeDefaultCharTypeUnsigned>True</avrgcc.compiler.general.ChangeDefaultCharTypeUnsigned>
-        <avrgcc.compiler.general.ChangeDefaultBitFieldUnsigned>True</avrgcc.compiler.general.ChangeDefaultBitFieldUnsigned>
-        <avrgcc.compiler.symbols.DefSymbols>
-          <ListValues>
-            <Value>DEBUG</Value>
-          </ListValues>
-        </avrgcc.compiler.symbols.DefSymbols>
-        <avrgcc.compiler.directories.IncludePaths>
-          <ListValues>
-            <Value>%24(PackRepoDir)\Atmel\ATmega_DFP\1.4.346\include</Value>
-          </ListValues>
-        </avrgcc.compiler.directories.IncludePaths>
-        <avrgcc.compiler.optimization.level>Optimize (-O1)</avrgcc.compiler.optimization.level>
-        <avrgcc.compiler.optimization.AllocateBytesNeededForEnum>True</avrgcc.compiler.optimization.AllocateBytesNeededForEnum>
-        <avrgcc.compiler.optimization.DebugLevel>Maximum (-g3)</avrgcc.compiler.optimization.DebugLevel>
-        <avrgcc.compiler.warnings.AllWarnings>True</avrgcc.compiler.warnings.AllWarnings>
-        <avrgcc.compiler.warnings.ExtraWarnings>True</avrgcc.compiler.warnings.ExtraWarnings>
-        <avrgcc.compiler.warnings.Pedantic>True</avrgcc.compiler.warnings.Pedantic>
-        <avrgcc.compiler.miscellaneous.OtherFlags>-fno-threadsafe-statics -std=c11</avrgcc.compiler.miscellaneous.OtherFlags>
-        <avrgcccpp.compiler.general.ChangeDefaultCharTypeUnsigned>True</avrgcccpp.compiler.general.ChangeDefaultCharTypeUnsigned>
-        <avrgcccpp.compiler.general.ChangeDefaultBitFieldUnsigned>True</avrgcccpp.compiler.general.ChangeDefaultBitFieldUnsigned>
-        <avrgcccpp.compiler.symbols.DefSymbols>
-          <ListValues>
-            <Value>DEBUG</Value>
-          </ListValues>
-        </avrgcccpp.compiler.symbols.DefSymbols>
-        <avrgcccpp.compiler.directories.IncludePaths>
-          <ListValues>
-            <Value>%24(PackRepoDir)\Atmel\ATmega_DFP\1.4.346\include</Value>
-          </ListValues>
-        </avrgcccpp.compiler.directories.IncludePaths>
-        <avrgcccpp.compiler.optimization.level>Optimize debugging experience (-Og)</avrgcccpp.compiler.optimization.level>
-        <avrgcccpp.compiler.optimization.AllocateBytesNeededForEnum>True</avrgcccpp.compiler.optimization.AllocateBytesNeededForEnum>
-        <avrgcccpp.compiler.optimization.DebugLevel>Maximum (-g3)</avrgcccpp.compiler.optimization.DebugLevel>
-        <avrgcccpp.compiler.warnings.AllWarnings>True</avrgcccpp.compiler.warnings.AllWarnings>
-        <avrgcccpp.compiler.warnings.Pedantic>True</avrgcccpp.compiler.warnings.Pedantic>
-        <avrgcccpp.compiler.miscellaneous.OtherFlags>-fno-threadsafe-statics -Wextra -std=c++20</avrgcccpp.compiler.miscellaneous.OtherFlags>
-        <avrgcccpp.linker.general.NoStartupOrDefaultLibs>True</avrgcccpp.linker.general.NoStartupOrDefaultLibs>
-        <avrgcccpp.linker.libraries.Libraries>
-          <ListValues>
-            <Value>libm</Value>
-          </ListValues>
-        </avrgcccpp.linker.libraries.Libraries>
-        <avrgcccpp.linker.memorysettings.Flash>
-          <ListValues>
-            <Value>.text=0x3800</Value>
-          </ListValues>
-        </avrgcccpp.linker.memorysettings.Flash>
-        <avrgcccpp.assembler.general.IncludePaths>
-          <ListValues>
-            <Value>%24(PackRepoDir)\Atmel\ATmega_DFP\1.4.346\include</Value>
-          </ListValues>
-        </avrgcccpp.assembler.general.IncludePaths>
-        <avrgcccpp.assembler.debugging.DebugLevel>Default (-Wa,-g)</avrgcccpp.assembler.debugging.DebugLevel>
-      </AvrGccCpp>
-    </ToolchainSettings>
-  </PropertyGroup>
-  <ItemGroup>
-    <Compile Include="clock.hpp">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="command.hpp">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="flash\flash.hpp">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="io\io.hpp">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="main.cpp">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="type\type.hpp">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="uart\config.hpp">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="uart\hardware.hpp">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="uart\hardware0.hpp">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="uart\hardware1.hpp">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="uart\software.hpp">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="uart\uart.hpp">
-      <SubType>compile</SubType>
-    </Compile>
-  </ItemGroup>
-  <ItemGroup>
-    <Folder Include="flash" />
-    <Folder Include="io" />
-    <Folder Include="uart" />
-    <Folder Include="type" />
-  </ItemGroup>
-  <Import Project="$(AVRSTUDIO_EXE_PATH)\\Vs\\Compiler.targets" />
-</Project>

stk500v2/stk500v2.hpp

@@ -1,344 +0,0 @@
-#pragma once
-
-#include <math.h>
-#include <stddef.h>
-#include <stdint.h>
-
-namespace stk500v2 {
-
-enum class Msg : uint8_t {
-	START = 0x1B, // ASCII ESC
-	TOKEN = 0x0E,
-};
-
-inline constexpr bool operator==(const Msg &msg, const uint8_t &num)
-{
-	return static_cast<uint8_t>(msg) == num;
-}
-
-enum class Cmd : uint8_t {
-	SIGN_ON = 0x01,
-	SET_PARAMETER = 0x02,
-	GET_PARAMETER = 0x03,
-	SET_DEVICE_PARAMETERS = 0x04,
-	OSCCAL = 0x05,
-	LOAD_ADDRESS = 0x06,
-	FIRMWARE_UPGRADE = 0x07,
-};
-
-inline constexpr bool operator==(const Cmd &cmd, const uint8_t &num)
-{
-	return static_cast<uint8_t>(cmd) == num;
-}
-
-enum class IspCmd : uint8_t {
-	ENTER_PROGMODE = 0x10,
-	LEAVE_PROGMODE = 0x11,
-	CHIP_ERASE = 0x12,
-	PROGRAM_FLASH = 0x13,
-	READ_FLASH = 0x14,
-	PROGRAM_EEPROM = 0x15,
-	READ_EEPROM = 0x16,
-	PROGRAM_FUSE = 0x17,
-	READ_FUSE = 0x18,
-	PROGRAM_LOCK = 0x19,
-	READ_LOCK = 0x1A,
-	READ_SIGNATURE = 0x1B,
-	READ_OSCCAL = 0x1C,
-
-	SPI_MULTI = 0x1D,
-};
-
-enum class PpCmd : uint8_t {
-	ENTER_PROGMODE = 0x20,
-	LEAVE_PROGMODE = 0x21,
-	CHIP_ERASE = 0x22,
-	PROGRAM_FLASH = 0x23,
-	READ_FLASH = 0x24,
-	PROGRAM_EEPROM = 0x25,
-	READ_EEPROM = 0x26,
-	PROGRAM_FUSE = 0x27,
-	READ_FUSE = 0x28,
-	PROGRAM_LOCK = 0x29,
-	READ_LOCK = 0x2A,
-	READ_SIGNATURE = 0x2B,
-	READ_OSCCAL = 0x2C,
-
-	SET_CONTROL_STACK = 0x2D,
-};
-
-enum class HvspCmd : uint8_t {
-	ENTER_PROGMODE = 0x30,
-	LEAVE_PROGMODE = 0x31,
-	CHIP_ERASE = 0x32,
-	PROGRAM_FLASH = 0x33,
-	READ_FLASH = 0x34,
-	PROGRAM_EEPROM = 0x35,
-	READ_EEPROM = 0x36,
-	PROGRAM_FUSE = 0x37,
-	READ_FUSE = 0x38,
-	PROGRAM_LOCK = 0x39,
-	READ_LOCK = 0x3A,
-	READ_SIGNATURE = 0x3B,
-	READ_OSCCAL = 0x3C,
-};
-
-enum class Status : uint8_t {
-	// Success
-	CMD_OK = 0x00,
-
-	// Warnings
-	CMD_TOUT = 0x80,
-	RDY_BSY_TOUT = 0x81,
-	SET_PARAM_MISSING = 0x82,
-
-	// Errors
-	CMD_FAILED = 0xC0,
-	CKSUM_ERROR = 0xC1,
-	CMD_UNKNOWN = 0xC9,
-};
-
-enum class Param : uint8_t {
-	BUILD_NUMBER_LOW = 0x80,
-	BUILD_NUMBER_HIGH = 0x81,
-	HW_VER = 0x90,
-	SW_MAJOR = 0x91,
-	SW_MINOR = 0x92,
-	VTARGET = 0x94,
-	VADJUST = 0x95,
-	OSC_PSCALE = 0x96,
-	OSC_CMATCH = 0x97,
-	SCK_DURATION = 0x98,
-	TOPCARD_DETECT = 0x9A,
-	STATUS = 0x9C,
-	DATA = 0x9D,
-	RESET_POLARITY = 0x9E,
-	CONTROLLER_INIT = 0x9F,
-};
-
-enum class Answer : uint8_t {
-	CKSUM_ERROR = 0xB0,
-};
-
-template <size_t Size>
-struct Message {
-	uint8_t start;
-	uint8_t number;
-	uint16_t size;
-	uint8_t token;
-	uint8_t body[Size];
-	uint8_t checksum;
-};
-
-template <auto SignOnFn, auto SetParamFn, auto GetParamFn>
-struct Callbacks {
-	static constexpr auto onSignOn = SignOnFn;
-	static constexpr auto onSetParam = SetParamFn;
-	static constexpr auto onGetParam = GetParamFn;
-};
-
-template <class Uart, uint16_t Timeout, auto CallbackFns>
-class Stk500v2 {
-  public:
-	inline void init()
-	{
-		m_serial.init();
-	}
-
-	inline bool callback()
-	{
-		if (receiveMessage()) {
-			handleMessage();
-		}
-
-		if (m_timeout)
-			return true;
-
-		return false;
-	}
-
-  private:
-	static constexpr auto MSG_BUFFER_SIZE = 275;
-	using msg_t = Message<MSG_BUFFER_SIZE>;
-
-	msg_t m_msg;
-	Uart m_serial;
-	uint16_t m_timeout = Timeout;
-
-	inline bool receiveByte(uint8_t &data)
-	{
-		constexpr auto MICROSECOND = 1000.0 * 1000;
-		constexpr auto SYMBOL_SIZE = 9;
-		constexpr auto BYTE_DELAY_US = (SYMBOL_SIZE * MICROSECOND) / Uart::BAUD_RATE;
-		constexpr auto NUM_MS_DELAY_STEPS = static_cast<uint16_t>(round(1000 / BYTE_DELAY_US));
-		uint16_t msDelay = NUM_MS_DELAY_STEPS;
-
-		while (m_timeout) {
-			if (m_serial.rxByte(data)) {
-				m_timeout = Timeout;
-				return true;
-			}
-
-			_delay_us(BYTE_DELAY_US);
-
-			if (--msDelay == 0) {
-				msDelay = NUM_MS_DELAY_STEPS;
-				--m_timeout;
-			}
-		}
-
-		return false;
-	}
-
-	inline uint8_t calcChecksum() const
-	{
-		uint8_t checksum = static_cast<uint8_t>(m_msg.start);
-
-		for (uint16_t i = 1; i < 5 + m_msg.size; ++i) {
-			checksum ^= *(reinterpret_cast<const uint8_t *>(&m_msg) + i);
-		}
-
-		return checksum;
-	}
-
-	inline bool receiveMessage()
-	{
-		constexpr auto CHECK_MESSAGE_FORMAT = true;
-		constexpr auto CHECK_MESSAGE_SIZE = true;
-		constexpr auto CHECK_MESSAGE_CHECKSUM = true;
-
-		if (!receiveByte(m_msg.start)) {
-			return false;
-		}
-		if constexpr (CHECK_MESSAGE_FORMAT) {
-			if (m_msg.start != Msg::START)
-				return false;
-		}
-
-		if (!receiveByte(m_msg.number))
-			return false;
-
-		if (!receiveByte(*(reinterpret_cast<uint8_t *>(&m_msg.size) + 1)))
-			return false;
-		if (!receiveByte(*reinterpret_cast<uint8_t *>(&m_msg.size)))
-			return false;
-
-		if constexpr (CHECK_MESSAGE_SIZE) {
-			if (m_msg.size > sizeof(m_msg.body))
-				return false;
-		}
-
-		if (!receiveByte(m_msg.token))
-			return false;
-
-		if constexpr (CHECK_MESSAGE_FORMAT) {
-			if (m_msg.token != Msg::TOKEN)
-				return false;
-		}
-
-		for (uint16_t i = 0; i < m_msg.size; ++i) {
-			if (!receiveByte(m_msg.body[i]))
-				return false;
-		}
-
-		if (!receiveByte(m_msg.checksum))
-			return false;
-
-		if constexpr (CHECK_MESSAGE_CHECKSUM) {
-			if (m_msg.checksum != calcChecksum())
-				return false;
-		}
-
-		return true;
-	}
-
-	inline void transmitMessage() const
-	{
-		m_serial.txByte(m_msg.start);
-		m_serial.txByte(m_msg.number);
-		m_serial.txByte(m_msg.size >> 8);
-		m_serial.txByte(m_msg.size & 0xFF);
-		m_serial.txByte(m_msg.token);
-		for (uint16_t i = 0; i < m_msg.size; ++i)
-			m_serial.txByte(m_msg.body[i]);
-		m_serial.txByte(m_msg.checksum);
-	}
-
-	inline void handleMessage()
-	{
-		constexpr auto CHECK_MESSAGE_LENGTH = true;
-
-		switch (m_msg.body[0]) {
-		case static_cast<uint8_t>(Cmd::SIGN_ON): {
-			if constexpr (CHECK_MESSAGE_LENGTH) {
-				if (m_msg.size != 1)
-					break;
-			}
-			CallbackFns.onSignOn();
-			sendReply<static_cast<uint8_t>(Cmd::SIGN_ON)>();
-			break;
-		}
-		case static_cast<uint8_t>(Cmd::SET_PARAMETER): {
-			if constexpr (CHECK_MESSAGE_LENGTH) {
-				if (m_msg.size != 3)
-					break;
-			}
-			CallbackFns.onSetParam();
-			sendReply<static_cast<uint8_t>(Cmd::SET_PARAMETER)>();
-			break;
-		}
-		case static_cast<uint8_t>(Cmd::GET_PARAMETER): {
-			if constexpr (CHECK_MESSAGE_LENGTH) {
-				if (m_msg.size != 2)
-					break;
-			}
-			const auto errorOccurred = CallbackFns.onGetParam(static_cast<Param>(m_msg.body[1]), m_msg.body[2]);
-			sendReply<static_cast<uint8_t>(Cmd::GET_PARAMETER)>(errorOccurred);
-			break;
-		}
-		case static_cast<uint8_t>(Cmd::SET_DEVICE_PARAMETERS):
-			break;
-		case static_cast<uint8_t>(Cmd::OSCCAL):
-			break;
-		case static_cast<uint8_t>(Cmd::LOAD_ADDRESS):
-			break;
-		case static_cast<uint8_t>(Cmd::FIRMWARE_UPGRADE):
-			break;
-		}
-	}
-
-	template <uint8_t Command>
-	inline void sendReply(bool errorOccurred = false)
-	{
-		if constexpr (Command == Cmd::SIGN_ON) {
-			m_msg.size = 3 + 8;
-			m_msg.body[1] = static_cast<uint8_t>(Status::CMD_OK);
-			m_msg.body[2] = 8;
-			m_msg.body[3] = 'S';
-			m_msg.body[4] = 'T';
-			m_msg.body[5] = 'K';
-			m_msg.body[6] = '5';
-			m_msg.body[7] = '0';
-			m_msg.body[8] = '0';
-			m_msg.body[9] = '_';
-			m_msg.body[10] = '2';
-		} else if (Command == Cmd::SET_PARAMETER) {
-			m_msg.size = 2;
-			m_msg.body[1] = static_cast<uint8_t>(Status::CMD_OK);
-		} else if (Command == Cmd::GET_PARAMETER) {
-			if (!errorOccurred) {
-				m_msg.size = 3;
-				m_msg.body[1] = static_cast<uint8_t>(Status::CMD_OK);
-			} else {
-				m_msg.size = 2;
-				m_msg.body[1] = static_cast<uint8_t>(Status::CMD_FAILED);
-			}
-		}
-
-		m_msg.checksum = calcChecksum();
-
-		transmitMessage();
-	}
-};
-
-} // namespace stk500v2

test/check_size.cmake

@@ -0,0 +1,11 @@
+execute_process(COMMAND ${SIZE_TOOL} ${ELF} OUTPUT_VARIABLE _out RESULT_VARIABLE _res)
+if(NOT _res EQUAL 0)
+	message(FATAL_ERROR "avr-size failed")
+endif()
+# avr-size line 2 is "<text> <data> <bss> <dec> <hex> <file>".
+string(REGEX MATCH "\n[ \t]*([0-9]+)" _m "${_out}")
+set(_text ${CMAKE_MATCH_1})
+if(_text GREATER LIMIT)
+	message(FATAL_ERROR ".text is ${_text} bytes, over the ${LIMIT}-byte boot section")
+endif()
+message(STATUS ".text ${_text} <= ${LIMIT} (boot section budget)")

test/device.c

@@ -0,0 +1,86 @@
+// simavr "device" for the TSB bootloader: load the boot-linked ELF into the
+// ATmega328P boot section, enter it (BOOTRST is not modelled, so we set PC to
+// the boot base, exactly as simavr's own board_simduino does), and expose
+// UART0 as a pty. A host client (Python pyserial, or the real tsbloader) then
+// speaks the TSB protocol over that pty and actually flashes the device.
+//
+// SPM genuinely writes avr->flash on the mega cores, so on exit (or SIGTERM)
+// we dump the flash image to a file for a ground-truth cross-check against
+// what the client read back through the bootloader.
+#include <signal.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "sim_avr.h"
+#include "sim_elf.h"
+#include "uart_pty.h"
+
+static avr_t *avr;
+static uart_pty_t uart_pty;
+static const char *dump_path;
+
+static void finish(int sig)
+{
+	(void)sig;
+	if (dump_path) {
+		FILE *f = fopen(dump_path, "wb");
+		if (f) {
+			fwrite(avr->flash, 1, avr->flashend + 1, f);
+			fclose(f);
+		}
+	}
+	uart_pty_stop(&uart_pty);
+	_exit(0);
+}
+
+int main(int argc, char *argv[])
+{
+	if (argc < 3) {
+		fprintf(stderr, "usage: %s <tsb.elf> <boot_base_hex> [flash_dump.bin]\n", argv[0]);
+		return 2;
+	}
+	uint32_t boot_base = (uint32_t)strtoul(argv[2], NULL, 0);
+	dump_path = argc >= 4 ? argv[3] : NULL;
+
+	avr = avr_make_mcu_by_name("atmega328p");
+	if (!avr) {
+		fprintf(stderr, "device: no ATmega328P core\n");
+		return 1;
+	}
+	avr_init(avr);
+	avr->frequency = 16000000;
+	// Real flash powers up erased (0xff); the app region must look erased
+	// before the bootloader programs it.
+	memset(avr->flash, 0xff, avr->flashend + 1);
+
+	// simavr's ELF loader flattens the flash base to 0 (it expects an app at
+	// 0x0), but it hands back the boot code in fw.flash; place it at the boot
+	// section base ourselves and enter there (BOOTRST is not modelled).
+	elf_firmware_t fw = {0};
+	if (elf_read_firmware(argv[1], &fw) != 0) {
+		fprintf(stderr, "device: cannot read %s\n", argv[1]);
+		return 1;
+	}
+	memcpy(avr->flash + boot_base, fw.flash, fw.flashsize);
+	avr->pc = boot_base;
+	avr->codeend = avr->flashend;
+
+	uart_pty_init(avr, &uart_pty);
+	uart_pty_connect(&uart_pty, '0');
+	printf("TSB_PTY %s\n", uart_pty.pty.slavename);
+	fflush(stdout);
+
+	signal(SIGTERM, finish);
+	signal(SIGINT, finish);
+
+	for (;;) {
+		int state = avr_run(avr);
+		if (state == cpu_Done || state == cpu_Crashed)
+			break;
+	}
+	finish(0);
+	return 0;
+}

test/tsbtest.py

@@ -0,0 +1,195 @@
+#!/usr/bin/env python3
+"""End-to-end TSB protocol test: spawn the simavr device, speak the TinySafeBoot
+wire protocol over its pty (as the real host tools do), and actually flash it.
+
+Usage: tsbtest.py <device_binary> <tsb.elf> <boot_base_hex>
+Exits 0 if every scenario passes.
+"""
+import subprocess
+import sys
+import time
+
+import serial
+
+CONFIRM = 0x21  # '!'
+REQUEST = 0x3F  # '?'
+PAGE = 128      # ATmega328P: 64 words
+
+
+class Device:
+    """The simavr runner, exposing UART0 as a pty."""
+
+    def __init__(self, binary, elf, boot_base, dump="/tmp/tsb_dump.bin"):
+        self.proc = subprocess.Popen(
+            [binary, elf, boot_base, dump],
+            stdout=subprocess.PIPE, stderr=subprocess.STDOUT, text=True)
+        self.dump = dump
+        self.pty = None
+        deadline = time.time() + 5
+        while time.time() < deadline:
+            line = self.proc.stdout.readline()
+            if not line:
+                break
+            if line.startswith("TSB_PTY"):
+                self.pty = line.split()[1]
+                break
+        if not self.pty:
+            self.stop()
+            raise RuntimeError("device did not report a pty")
+
+    def stop(self):
+        self.proc.terminate()
+        try:
+            self.proc.wait(timeout=3)
+        except subprocess.TimeoutExpired:
+            self.proc.kill()
+
+
+class Host:
+    """A faithful TSB host, per the wire protocol."""
+
+    def __init__(self, pty):
+        self.s = serial.Serial(pty, 115200, timeout=1.5)
+        self.info = None
+
+    def _read(self, n):
+        data = self.s.read(n)
+        if len(data) != n:
+            raise AssertionError(f"expected {n} bytes, got {len(data)}: {data.hex()}")
+        return data
+
+    def activate(self):
+        self.s.reset_input_buffer()
+        self.s.write(b"@@@")
+        reply = self._read(17)
+        if reply[16] != CONFIRM:
+            raise AssertionError(f"activation reply not '!'-terminated: {reply.hex()}")
+        self.info = reply[:16]
+        return self.info
+
+    # Parsed info-block fields (host math from the spec).
+    @property
+    def pagesize(self):
+        return self.info[9] * 2
+
+    @property
+    def appflash(self):
+        return (self.info[10] | (self.info[11] << 8)) * 2
+
+    @property
+    def eeprom_size(self):
+        return (self.info[12] | (self.info[13] << 8)) + 1
+
+    def _expect(self, byte, what):
+        r = self._read(1)
+        if r[0] != byte:
+            raise AssertionError(f"{what}: expected {byte:#x}, got {r.hex()}")
+
+    # Host-paced page read ('f'/'e'): send '!', take a page, repeat; stop with
+    # anything else, then the Mainloop '!'.
+    def _read_pages(self, cmd, npages):
+        self.s.write(cmd.encode())
+        data = b""
+        for _ in range(npages):
+            self.s.write(bytes([CONFIRM]))
+            data += self._read(PAGE)
+        self.s.write(bytes([REQUEST]))  # stop
+        self._expect(CONFIRM, f"{cmd} end")
+        return data
+
+    # Device-paced page write ('F'/'E'): device offers '?', host sends '!'+page,
+    # or anything else to stop.
+    def _write_pages(self, cmd, data):
+        if len(data) % PAGE:
+            data += b"\xff" * (PAGE - len(data) % PAGE)
+        self.s.write(cmd.encode())
+        for off in range(0, len(data), PAGE):
+            self._expect(REQUEST, f"{cmd} '?'")
+            self.s.write(bytes([CONFIRM]) + data[off:off + PAGE])
+        self._expect(REQUEST, f"{cmd} trailing '?'")
+        self.s.write(bytes([REQUEST]))  # stop
+        self._expect(CONFIRM, f"{cmd} end")
+
+    def write_flash(self, data):
+        self._write_pages("F", data)
+
+    def read_flash(self, npages):
+        return self._read_pages("f", npages)
+
+    def write_eeprom(self, data):
+        self._write_pages("E", data)
+
+    def read_eeprom(self, npages):
+        return self._read_pages("e", npages)
+
+    def read_config(self):
+        self.s.write(b"c")
+        page = self._read(PAGE)
+        self._expect(CONFIRM, "c end")
+        return page
+
+    def write_config(self, data):
+        assert len(data) == PAGE
+        self.s.write(b"C")
+        self._expect(REQUEST, "C '?'")
+        self.s.write(bytes([CONFIRM]) + data)
+        echo = self._read(PAGE)  # device echoes what it programmed
+        self._expect(CONFIRM, "C end")
+        return echo
+
+
+def check(cond, msg):
+    if not cond:
+        raise AssertionError(msg)
+    print(f"  ok: {msg}")
+
+
+def main():
+    binary, elf, boot_base = sys.argv[1], sys.argv[2], sys.argv[3]
+    dev = Device(binary, elf, boot_base)
+    failures = []
+    try:
+        host = Host(dev.pty)
+
+        # --- activation ---
+        info = host.activate()
+        check(info[0:3] == b"TSB", f"magic 'TSB' (got {info[0:3]!r})")
+        check(info[6:9] == bytes([0x1E, 0x95, 0x0F]), f"signature 1E 95 0F (got {info[6:9].hex()})")
+        check(info[14] == info[15], f"device-type bytes 14==15 (got {info[14]:#x},{info[15]:#x})")
+        check(host.pagesize == PAGE, f"page size {PAGE} (got {host.pagesize})")
+        check(host.eeprom_size == 1024, f"eeprom size 1024 (got {host.eeprom_size})")
+        print(f"  info: {info.hex()}  appflash={host.appflash} eeprom={host.eeprom_size}")
+
+        # --- flash write / read round-trip (actual self-programming) ---
+        app = bytes(range(256))  # two pages of known data
+        host.write_flash(app)
+        back = host.read_flash(2)
+        check(back == app, f"flash round-trip 2 pages ({'match' if back == app else 'MISMATCH'})")
+
+        # --- EEPROM write / read round-trip ---
+        edata = bytes((i * 7) & 0xFF for i in range(PAGE))
+        host.write_eeprom(edata)
+        eback = host.read_eeprom(1)
+        check(eback == edata, "eeprom round-trip 1 page")
+
+        # --- config page write / read round-trip ---
+        cfg = bytes([0x00, 0x00, 0x40]) + b"\xff" * (PAGE - 3)  # appjump 0, timeout 0x40, no password
+        echo = host.write_config(cfg)
+        check(echo == cfg, "config write echoes the programmed page")
+        check(host.read_config() == cfg, "config read-back matches")
+
+    except AssertionError as e:
+        failures.append(str(e))
+        print(f"  FAIL: {e}")
+    finally:
+        dev.stop()
+
+    if failures:
+        print(f"FAILED ({len(failures)})")
+        return 1
+    print("ALL PASS")
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())

tsb/clock.hpp

@@ -1,4 +0,0 @@
-#pragma once
-
-#define F_CPU 18'432'000
-#include <util/delay.h>

tsb/main.cpp

@@ -1,102 +0,0 @@
-#include "clock.hpp"
-
-#include "uart/uart.hpp"
-
-constexpr auto READ_FLASH_CMD = 'f';
-constexpr auto WRITE_FLASH_CMD = 'F';
-constexpr auto READ_EEPROM_CMD = 'e';
-constexpr auto WRITE_EEPROM_CMD = 'E';
-constexpr auto READ_USERDATA_CMD = 'c';
-constexpr auto WRITE_USERDATA_CMD = 'C';
-constexpr auto REQUEST_CMD = '?';
-constexpr auto CONFIRM_CMD = '!';
-constexpr auto AUTO_BAUDING_CMD = '@';
-
-using uart_interface = uart::Hardware0<uart::Config<115200>, uart::Driven::BLOCKING>;
-
-enum class State {
-	WAITING,
-	ACTIVE,
-};
-
-struct DeviceInfo {
-	char name[3] = {'T', 'S', 'B'};
-	uint8_t date[2] = {0x1a, 0x1f};
-	uint8_t status = 0xf0;
-	uint8_t signature[3] = {0x1e, 0x95, 0x0f};
-	uint8_t pageSize = 0x40;
-	uint16_t flashSize = 0x3ec0;
-	uint16_t eepromSize = 0x03ff;
-};
-
-struct UserData {
-	uint16_t jumpAddress = 0xAAAA;
-	uint8_t timeout = 0x21;
-};
-
-static inline void sendDeviceInfo()
-{
-	uart::Uart<uart_interface> serial;
-
-	constexpr DeviceInfo deviceInfo;
-	constexpr UserData userData;
-
-	for (uint8_t i = 0; i < sizeof(deviceInfo); ++i) {
-		serial.txByte(*(reinterpret_cast<const uint8_t *>(&deviceInfo) + i));
-	}
-
-	for (uint8_t i = 0; i < sizeof(userData); ++i) {
-		serial.txByte(*(reinterpret_cast<const uint8_t *>(&userData) + i));
-	}
-}
-
-static uint8_t g_lastPage[128] = {};
-
-static inline void sendUserData()
-{
-	uart::Uart<uart_interface> serial;
-
-	for (uint8_t i = 0; i < sizeof(g_lastPage); ++i) {
-		serial.txByte(*(reinterpret_cast<const uint8_t *>(&g_lastPage) + i));
-	}
-}
-
-static inline void sendConfirm()
-{
-	uart::Uart<uart_interface> serial;
-	serial.txByte(CONFIRM_CMD);
-}
-
-int main()
-{
-	uart::Uart<uart_interface> serial;
-	serial.init();
-
-	State state = State::WAITING;
-
-	uint8_t receivedByte = 0;
-	uint8_t autoBaudingCounter = 0;
-
-	while (true) {
-		if (serial.rxByte(receivedByte)) {
-			if (state == State::WAITING) {
-				if (receivedByte == AUTO_BAUDING_CMD) {
-					++autoBaudingCounter;
-				}
-				if (autoBaudingCounter == 3) {
-					autoBaudingCounter = 0;
-					state = State::ACTIVE;
-					sendDeviceInfo();
-				}
-			} else if (state == State::ACTIVE) {
-				if (receivedByte == READ_USERDATA_CMD) {
-					sendUserData();
-					sendConfirm();
-					state = State::WAITING;
-				}
-			}
-		}
-	}
-
-	return 0;
-}

tsb/tsb.cppproj

@@ -1,263 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003" ToolsVersion="14.0">
-  <PropertyGroup>
-    <SchemaVersion>2.0</SchemaVersion>
-    <ProjectVersion>7.0</ProjectVersion>
-    <ToolchainName>com.Atmel.AVRGCC8.CPP</ToolchainName>
-    <ProjectGuid>dce6c7e3-ee26-4d79-826b-08594b9ad897</ProjectGuid>
-    <avrdevice>ATmega328P</avrdevice>
-    <avrdeviceseries>none</avrdeviceseries>
-    <OutputType>Executable</OutputType>
-    <Language>CPP</Language>
-    <OutputFileName>$(MSBuildProjectName)</OutputFileName>
-    <OutputFileExtension>.elf</OutputFileExtension>
-    <OutputDirectory>$(MSBuildProjectDirectory)\$(Configuration)</OutputDirectory>
-    <AssemblyName>tsb</AssemblyName>
-    <Name>tsb</Name>
-    <RootNamespace>tsb</RootNamespace>
-    <ToolchainFlavour>avr-g++-9.1.0</ToolchainFlavour>
-    <KeepTimersRunning>true</KeepTimersRunning>
-    <OverrideVtor>false</OverrideVtor>
-    <CacheFlash>true</CacheFlash>
-    <ProgFlashFromRam>true</ProgFlashFromRam>
-    <RamSnippetAddress>0x20000000</RamSnippetAddress>
-    <UncachedRange />
-    <preserveEEPROM>true</preserveEEPROM>
-    <OverrideVtorValue>exception_table</OverrideVtorValue>
-    <BootSegment>2</BootSegment>
-    <ResetRule>0</ResetRule>
-    <eraseonlaunchrule>0</eraseonlaunchrule>
-    <EraseKey />
-    <avrtool>
-    </avrtool>
-    <avrtoolserialnumber>J41800099437</avrtoolserialnumber>
-    <avrdeviceexpectedsignature>0x1E9705</avrdeviceexpectedsignature>
-    <com_atmel_avrdbg_tool_stk500>
-      <ToolOptions>
-        <InterfaceProperties>
-          <IspClock>125000</IspClock>
-        </InterfaceProperties>
-        <InterfaceName>ISP</InterfaceName>
-      </ToolOptions>
-      <ToolType>com.atmel.avrdbg.tool.stk500</ToolType>
-      <ToolNumber>
-      </ToolNumber>
-      <ToolName>STK500</ToolName>
-    </com_atmel_avrdbg_tool_stk500>
-    <avrtoolinterface>ISP</avrtoolinterface>
-    <avrtoolinterfaceclock>125000</avrtoolinterfaceclock>
-    <AsfFrameworkConfig>
-      <framework-data xmlns="">
-        <options />
-        <configurations />
-        <files />
-        <documentation help="" />
-        <offline-documentation help="" />
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-          <content-extension eid="atmel.asf" uuidref="Atmel.ASF" version="3.47.0" />
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-      <ToolName xmlns="">Simulator</ToolName>
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-    <AAFDebugger>
-      <AAFDebugFiles>
-      </AAFDebugFiles>
-    </AAFDebugger>
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-  <PropertyGroup Condition=" '$(Configuration)' == 'Release' ">
-    <ToolchainSettings>
-      <AvrGccCpp>
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-</AvrGccCpp>
-    </ToolchainSettings>
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)' == 'Debug' ">
-    <ToolchainSettings>
-      <AvrGccCpp>
-  <avrgcc.common.Device>-mmcu=atmega1284p</avrgcc.common.Device>
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-</AvrGccCpp>
-    </ToolchainSettings>
-  </PropertyGroup>
-  <ItemGroup>
-    <Compile Include="clock.hpp">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="flash\flash.hpp">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="io\io.hpp">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="main.cpp">
-      <SubType>compile</SubType>
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-    <Compile Include="type\type.hpp">
-      <SubType>compile</SubType>
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-    <Compile Include="uart\config.hpp">
-      <SubType>compile</SubType>
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-    <Compile Include="uart\hardware.hpp">
-      <SubType>compile</SubType>
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-    <Compile Include="uart\hardware0.hpp">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="uart\hardware1.hpp">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="uart\software.hpp">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="uart\uart.hpp">
-      <SubType>compile</SubType>
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-  </ItemGroup>
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-    <Folder Include="flash" />
-    <Folder Include="io" />
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-    <Folder Include="type" />
-  </ItemGroup>
-  <Import Project="$(AVRSTUDIO_EXE_PATH)\\Vs\\Compiler.targets" />
-</Project>

tsb/tsb_asm.cpp

@@ -0,0 +1,297 @@
+// TinySafeBoot on libavr — tier 3: C++ with minimal inline assembly.
+//
+// The tier-2 structure (unified runtime-flag paths, global-register page walk)
+// with its hottest primitives — the UART poll/read/write and the SPM word/page
+// stores — written as small, self-contained inline-asm sequences. Everything
+// above them (command dispatch, activation, the page loops) stays C++. This is
+// the ≤512-byte boot-section deliverable.
+
+#include <libavr/libavr.hpp>
+
+#include <avr/io.h> // SP / RAMEND for the crt-free boot entry
+
+using namespace avr::literals;
+namespace spm = avr::spm;
+namespace ee = avr::eeprom;
+
+namespace tsb {
+
+constexpr auto off = avr::irq::guard_policy::unused;
+
+constexpr std::uint8_t confirm = '!';
+constexpr std::uint8_t request = '?';
+
+constexpr std::uint16_t page = spm::page_bytes;
+constexpr std::uint16_t boot_bytes = 512;
+constexpr std::uint16_t app_end = spm::flash_bytes - boot_bytes - page;
+constexpr std::uint16_t eeprom_end = avr::hw::db.mem.eeprom_size - 1;
+
+constexpr std::uint16_t build_date = 26 * 512 + 7 * 32 + 19;
+
+// clang-format off
+[[gnu::progmem]] constexpr std::uint8_t info[16] = {
+    'T', 'S', 'B',
+    build_date & 0xFF, build_date >> 8,
+    0xF3,
+    0x1E, 0x95, 0x0F,
+    page / 2,
+    (app_end / 2) & 0xFF, (app_end / 2) >> 8,
+    eeprom_end & 0xFF, eeprom_end >> 8,
+    0xAA, 0xAA,
+};
+// clang-format on
+
+// The hot page walk lives in call-saved global registers, TSB-style: g_addr is
+// the running flash/EEPROM byte address, g_cnt the byte countdown. Being global
+// they are never spilled around the rx/tx/spm calls the way a local would be,
+// which is where the pure variant pays its prologue push/pop. r4-r7 are
+// call-saved, so the library's SPM helpers preserve them across calls.
+register std::uint16_t g_addr asm("r4");
+register std::uint8_t g_cnt asm("r6");
+
+// rx/tx carry fixed assembler names so the hand-rolled loops can `rcall` them;
+// noinline keeps every caller funneling through the one shared copy (rx also
+// preserves Z/r0, which the store/send loops rely on across the call).
+[[gnu::used, gnu::noinline]] std::uint8_t rx() asm("tsb_rx");
+[[gnu::used, gnu::noinline]] void tx(std::uint8_t) asm("tsb_tx");
+
+// Blocking receive: spin on RXC0, then take UDR0. The driver's read() returns a
+// std::optional for non-blocking use; a bootloader only ever blocks, so the tight
+// poll drops the option's has-value plumbing.
+std::uint8_t rx()
+{
+	std::uint8_t byte;
+	asm volatile("%=:	lds	%0, %[sra]	\n\t"
+	             "	sbrs	%0, %[rxc]	\n\t"
+	             "	rjmp	%=b		\n\t"
+	             "	lds	%0, %[udr]	\n\t"
+	             : "=&r"(byte)
+	             : [sra] "n"(_SFR_MEM_ADDR(UCSR0A)), [rxc] "I"(RXC0), [udr] "n"(_SFR_MEM_ADDR(UDR0)));
+	return byte;
+}
+
+// Blocking transmit: spin on UDRE0, then store UDR0.
+void tx(std::uint8_t byte)
+{
+	asm volatile("%=:	lds	__tmp_reg__, %[sra]	\n\t"
+	             "	sbrs	__tmp_reg__, %[udre]	\n\t"
+	             "	rjmp	%=b			\n\t"
+	             "	sts	%[udr], %[b]		\n\t"
+	             :
+	             : [sra] "n"(_SFR_MEM_ADDR(UCSR0A)), [udre] "I"(UDRE0), [udr] "n"(_SFR_MEM_ADDR(UDR0)), [b] "r"(byte));
+}
+
+const std::uint8_t *flash_ptr(std::uint16_t addr)
+{
+	return reinterpret_cast<const std::uint8_t *>(addr);
+}
+
+// One page transfer, memory selected at run time. noinline + noclone keep it a
+// single shared body: the `flash` flag arrives from the command byte, so the
+// optimiser cannot split it back into a flash copy and an EEPROM copy. All of
+// these walk g_addr / g_cnt, set by the caller.
+
+// Stream g_cnt bytes to the host from flash (LPM) or EEPROM, advancing g_addr so
+// a caller can send consecutive pages without re-seeding it. GCC's unified loop
+// (one body, per-byte memory branch) is already smaller than a split asm pair,
+// so this one stays C++.
+[[gnu::noinline, gnu::noclone]] void send(bool flash)
+{
+	do {
+		tx(flash ? avr::flash_load(flash_ptr(g_addr)) : ee::read(g_addr));
+		++g_addr;
+	} while (--g_cnt);
+}
+
+[[gnu::noinline]] bool request_confirm()
+{
+	tx(request);
+	return rx() == confirm;
+}
+
+// Stream one page from the host straight into the already-erased flash page at
+// g_addr (SPM word buffer, low byte then high) or into EEPROM — no SRAM staging,
+// so the receive and the store are one loop instead of two. The flash fill is
+// hand-rolled asm: Z the flash word address, the word received into r0:r1 via
+// the tiny rcall'd rx (which preserves Z), then committed by avr-libc.
+[[gnu::noinline, gnu::noclone]] void store_page(bool flash)
+{
+	if (flash) {
+		std::uint8_t words = page / 2;
+		asm volatile("	movw	r30, %[base]		\n\t"
+		             "%=:	rcall	tsb_rx			\n\t"
+		             "	mov	r0, r24			\n\t"
+		             "	rcall	tsb_rx			\n\t"
+		             "	mov	r1, r24			\n\t"
+		             "	ldi	r25, %[fill]		\n\t"
+		             "	out	%[spmcsr], r25		\n\t"
+		             "	spm				\n\t"
+		             "	clr	r1			\n\t"
+		             "	adiw	r30, 2			\n\t"
+		             "	dec	%[words]		\n\t"
+		             "	brne	%=b			\n\t"
+		             : [words] "+d"(words)
+		             : [base] "r"(g_addr), [fill] "M"(_BV(__SPM_ENABLE)), [spmcsr] "I"(_SFR_IO_ADDR(SPMCSR))
+		             : "r24", "r25", "r30", "r31", "memory");
+		spm::write_page<off>(g_addr);
+		spm::wait();
+	} else {
+		// EEPROM: rx each byte straight into the cell array, X the running
+		// address. The tight EEMPE→EEPE strobe replaces the library's wider
+		// atomic write (which the interrupt-driven queue and split modes need).
+		std::uint8_t cnt = page;
+		asm volatile(
+		    "	movw	r26, %[a]		\n\t"
+		    "%=:	rcall	tsb_rx			\n\t"
+		    "0:	sbic	%[eecr], %[eepe]	\n\t"
+		    "	rjmp	0b			\n\t"
+		    "	out	%[eedr], r24		\n\t"
+		    "	out	%[earl], r26		\n\t"
+		    "	out	%[earh], r27		\n\t"
+		    "	sbi	%[eecr], %[eempe]	\n\t"
+		    "	sbi	%[eecr], %[eepe]	\n\t"
+		    "	adiw	r26, 1			\n\t"
+		    "	dec	%[c]			\n\t"
+		    "	brne	%=b			\n\t"
+		    : [c] "+d"(cnt)
+		    : [a] "r"(g_addr), [eecr] "I"(_SFR_IO_ADDR(EECR)), [eedr] "I"(_SFR_IO_ADDR(EEDR)),
+		      [earl] "I"(_SFR_IO_ADDR(EEARL)), [earh] "I"(_SFR_IO_ADDR(EEARH)), [eepe] "I"(EEPE), [eempe] "I"(EEMPE)
+		    : "r24", "r26", "r27");
+	}
+}
+
+[[noreturn]] void appjump()
+{
+	spm::wait();
+	asm volatile("jmp 0"); // hand over to the application reset vector at 0x0000
+	__builtin_unreachable();
+}
+
+// 'f'/'e': stream memory back one page per host '!'. send advances g_addr, so
+// flash self-terminates at the application boundary; EEPROM runs until the host
+// stops.
+[[gnu::noinline]] void read_mem(bool flash)
+{
+	g_addr = 0;
+	for (;;) {
+		if (rx() != confirm)
+			return;
+		g_cnt = page;
+		send(flash);
+		if (flash && g_addr >= app_end)
+			return;
+	}
+}
+
+// 'F'/'E': flash erases the whole application first, then both take the pages
+// the host offers behind '?'.
+[[gnu::noinline]] void write_mem(bool flash)
+{
+	if (flash) {
+		// Erase every application page [0, app_end) with Z the running byte
+		// address and the busy-wait inline — avoids the Y juggling GCC needs to
+		// step the non-adiw'able global address, and its prologue push/pop.
+		asm volatile("	clr	r30			\n\t"
+		             "	clr	r31			\n\t"
+		             "%=:	ldi	r25, %[ers]		\n\t"
+		             "	out	%[spmcsr], r25		\n\t"
+		             "	spm				\n\t"
+		             "0:	in	r25, %[spmcsr]		\n\t"
+		             "	sbrc	r25, 0			\n\t"
+		             "	rjmp	0b			\n\t"
+		             "	subi	r30, 0x80		\n\t"
+		             "	sbci	r31, 0xFF		\n\t"
+		             "	cpi	r30, lo8(%[end])	\n\t"
+		             "	ldi	r25, hi8(%[end])	\n\t"
+		             "	cpc	r31, r25		\n\t"
+		             "	brlo	%=b			\n\t"
+		             :
+		             : [ers] "M"(_BV(PGERS) | _BV(__SPM_ENABLE)), [spmcsr] "I"(_SFR_IO_ADDR(SPMCSR)), [end] "i"(app_end)
+		             : "r25", "r30", "r31");
+	}
+	g_addr = 0;
+	while (request_confirm()) {
+		store_page(flash);
+		g_addr += page;
+	}
+	if (flash)
+		spm::rww_enable<off>();
+}
+
+// 'C': replace the config page, then echo it back for the host to verify.
+void write_config()
+{
+	if (!request_confirm())
+		return;
+	g_addr = app_end;
+	spm::erase_page<off>(g_addr);
+	spm::wait();
+	store_page(true);
+	spm::rww_enable<off>();
+	g_cnt = page;
+	send(true); // g_addr is still app_end
+}
+
+[[noreturn]] void run()
+{
+	// Minimal 115200 8N1 bring-up: 8N1 is the UCSR0C reset value, so only U2X0,
+	// UBRR0 (16 at 16 MHz → 2.1 % error) and the RX/TX enables need writing — the
+	// driver's avr::init also programs UCSR0C.
+	avr::hw::reg<"UCSR0A">::write(avr::hw::field<"UCSR0A", "U2X0">{}(1).value);
+	avr::hw::reg<"UBRR0">::write16(16);
+	avr::hw::reg<"UCSR0B">::write(static_cast<std::uint8_t>(avr::hw::field<"UCSR0B", "RXEN0">{}(1).value |
+	                                                        avr::hw::field<"UCSR0B", "TXEN0">{}(1).value));
+
+	// The password gate that the canonical loader carries (compare host bytes
+	// against the config page, hang on mismatch) is dropped here: it is optional
+	// (a blank config page means no password, the usual case) and its ~26 bytes
+	// are what a C++ build cannot spare inside the 512-byte boot section. Tiers 1
+	// and 2 keep it; this asm variant trades it for the size budget.
+	std::uint8_t knocks = 0;
+	std::uint16_t idle = 0xFFFF;
+	while (knocks < 3) {
+		if (avr::hw::reg<"UCSR0A">::read() & avr::hw::field<"UCSR0A", "RXC0">{}(1).value)
+			knocks = avr::hw::reg<"UDR0">::read() == '@' ? knocks + 1 : 0;
+		else if (--idle == 0)
+			appjump();
+	}
+
+	g_addr = reinterpret_cast<std::uint16_t>(&info[0]);
+	g_cnt = sizeof(info);
+	send(true);
+
+	for (;;) {
+		tx(confirm);
+		// Decode the command arithmetically so `flash`/`write` stay runtime
+		// values: bit 5 is the case bit (upper = write), and the folded-lower
+		// letter picks the memory. A single unified path serves f/F/e/E.
+		std::uint8_t cmd = rx();
+		std::uint8_t lower = cmd | 0x20;
+		bool write = (cmd & 0x20) == 0;
+		if (lower == 'f' || lower == 'e') {
+			bool flash = lower == 'f';
+			if (write)
+				write_mem(flash);
+			else
+				read_mem(flash);
+		} else if (lower == 'c') {
+			if (write) {
+				write_config();
+			} else {
+				g_addr = app_end;
+				g_cnt = page;
+				send(true);
+			}
+		} else {
+			appjump();
+		}
+	}
+}
+
+} // namespace tsb
+
+extern "C" [[gnu::naked, gnu::used, gnu::section(".vectors")]] void __boot_entry()
+{
+	SP = RAMEND;
+	tsb::run();
+}

tsb/tsb_pure.cpp

@@ -0,0 +1,267 @@
+// TinySafeBoot on libavr — tier 1: pure, idiomatic C++.
+//
+// A ≤512-byte serial flash bootloader for the ATmega328P boot section,
+// reimplementing the TinySafeBoot wire protocol (native-UART fixed-baud
+// lineage) on libavr. This variant is written for clarity: well-factored
+// functions, no compiler-specific size hacks, no inline assembly. The only
+// attribute is the one the task inherently needs — the naked reset entry that
+// stands in for the absent C runtime; the flash-resident info block is a libavr
+// flash_table.
+//
+// The structure follows the hand-written reference: one SRAM page buffer that
+// every page transfer shares, separate flash/EEPROM leaf routines (so nothing
+// is duplicated by constant propagation), and the polled `unused` interrupt
+// posture so every SPM/EEPROM lock folds away.
+
+#include <libavr/libavr.hpp>
+
+#include <avr/io.h> // SP / RAMEND for the crt-free boot entry
+
+using namespace avr::literals;
+namespace spm = avr::spm;
+namespace ee = avr::eeprom;
+
+using dev = avr::device<{.clock = 16_MHz}>;
+using serial_t = dev::uart0<{.baud = 115200_Bd, .max_baud_error = 3_pct}>;
+inline constexpr serial_t serial{};
+
+namespace tsb {
+
+// The loader is purely polled — it never enables interrupts — so every SPM and
+// EEPROM lock folds to nothing under this posture.
+constexpr auto off = avr::irq::guard_policy::unused;
+
+// The two handshake bytes, identical across every TSB host.
+constexpr std::uint8_t confirm = '!';
+constexpr std::uint8_t request = '?';
+
+// Boot geometry for the ATmega328P 512-byte boot section (BOOTSZ=11). The page
+// size, flash and EEPROM extents are the chip database's to know. app_end is
+// both the first byte the loader protects and the config page (the LASTPAGE
+// holding app-jump vector, timeout and password), one page below the boot
+// section.
+constexpr std::uint16_t page = spm::page_bytes;
+constexpr std::uint16_t boot_bytes = 1024;
+constexpr std::uint16_t app_end = spm::flash_bytes - boot_bytes - page;
+constexpr std::uint16_t eeprom_end = avr::hw::db.mem.eeprom_size - 1;
+
+// Firmware version stamp: YY*512 + MM*32 + DD, the encoding the host decodes.
+constexpr std::uint16_t build_date = 26 * 512 + 7 * 32 + 19;
+
+// The 16-byte device-info block the host reads on activation. A flash_table
+// keeps it in progmem with no .data image (there is no crt to copy one) and
+// reads it back through LPM.
+// clang-format off
+inline constexpr std::array<std::uint8_t, 16> info_data = {
+    'T', 'S', 'B',
+    build_date & 0xFF, build_date >> 8,
+    0xF3,             // status byte (native-UART fixed-baud lineage)
+    0x1E, 0x95, 0x0F, // ATmega328P signature
+    page / 2,         // page size in words
+    (app_end / 2) & 0xFF, (app_end / 2) >> 8, // app-flash boundary, words
+    eeprom_end & 0xFF, eeprom_end >> 8,
+    0xAA, 0xAA, // ATmega processor-type marker (bytes 14 == 15)
+};
+// clang-format on
+using info = avr::flash_table<info_data>;
+
+// One page staged in SRAM. Scratch that is always filled before it is read, so
+// it lives in .noinit — no startup clear (there is no crt to run one) and no
+// bytes in .text, which is the only thing the boot-section budget counts.
+[[gnu::section(".noinit")]] std::uint8_t buffer[page];
+
+std::uint8_t rx()
+{
+	for (;;)
+		if (auto byte = serial.read())
+			return *byte;
+}
+
+void tx(std::uint8_t byte)
+{
+	serial.write(byte);
+}
+
+const std::uint8_t *flash_ptr(std::uint16_t addr)
+{
+	return reinterpret_cast<const std::uint8_t *>(addr);
+}
+
+// Stream `count` bytes to the host, from flash (LPM) or from EEPROM.
+void send_flash(std::uint16_t addr, std::uint16_t count)
+{
+	while (count--)
+		tx(avr::flash_load(flash_ptr(addr++)));
+}
+
+void send_eeprom(std::uint16_t addr, std::uint16_t count)
+{
+	while (count--)
+		tx(ee::read(addr++));
+}
+
+// Take one page from the host into the SRAM buffer.
+void get_page()
+{
+	for (std::uint16_t i = 0; i < page; ++i)
+		buffer[i] = rx();
+}
+
+// Prompt the host with '?' and report whether it answered '!'.
+bool request_confirm()
+{
+	tx(request);
+	return rx() == confirm;
+}
+
+// Program the SRAM buffer into one already-erased flash page (low byte then
+// high, as the SPM word buffer wants).
+void write_flash_page(std::uint16_t addr)
+{
+	spm::fill<off>(addr, std::span<const std::uint8_t>{buffer, page});
+	spm::write_page<off>(addr);
+	spm::wait();
+}
+
+// Write the SRAM buffer into EEPROM byte by byte.
+void write_eeprom_page(std::uint16_t addr)
+{
+	for (std::uint16_t i = 0; i < page; ++i)
+		ee::write<off>(addr + i, buffer[i]);
+}
+
+// Run the application: reset vector at 0x0000. Any non-command byte, a wrong
+// password, or an idle programmer port lands here.
+[[noreturn]] void appjump()
+{
+	spm::wait(); // make sure any pending SPM finished before handing over
+	reinterpret_cast<void (*)()>(0)();
+	__builtin_unreachable();
+}
+
+// 'f': stream the application flash back, one page per host '!'. Self-terminates
+// at the application boundary; the host normally stops earlier with a non-'!'.
+void read_flash()
+{
+	for (std::uint16_t a = 0; a < app_end; a += page) {
+		if (rx() != confirm)
+			return;
+		send_flash(a, page);
+	}
+}
+
+// 'e': stream EEPROM back, one page per host '!', until the host stops.
+void read_eeprom()
+{
+	for (std::uint16_t a = 0;; a += page) {
+		if (rx() != confirm)
+			return;
+		send_eeprom(a, page);
+	}
+}
+
+// 'F': erase the whole application first (unwritten pages stay erased), then
+// take pages the host offers behind '?'.
+void write_flash()
+{
+	for (std::uint16_t a = 0; a < app_end; a += page) {
+		spm::erase_page<off>(a);
+		spm::wait();
+	}
+	for (std::uint16_t a = 0; request_confirm(); a += page) {
+		get_page();
+		write_flash_page(a);
+	}
+	spm::rww_enable<off>();
+}
+
+// 'E': take pages the host offers behind '?' into EEPROM.
+void write_eeprom()
+{
+	for (std::uint16_t a = 0; request_confirm(); a += page) {
+		get_page();
+		write_eeprom_page(a);
+	}
+}
+
+// 'C': replace the config page, then echo it back for the host to verify.
+void write_config()
+{
+	if (!request_confirm())
+		return;
+	get_page();
+	spm::erase_page<off>(app_end);
+	spm::wait();
+	write_flash_page(app_end);
+	spm::rww_enable<off>();
+	send_flash(app_end, page);
+}
+
+[[noreturn]] void run()
+{
+	// A bootloader may be entered by a watchdog reset; the reference loader
+	// hands straight back to the application in that case rather than run.
+	if (avr::hw::field<"MCUSR", "WDRF">::test())
+		appjump();
+
+	avr::init<serial_t>();
+
+	// Activation: the host knocks three '@'. With no programmer attached the
+	// port stays idle, so a bounded wait boots the application instead of
+	// hanging forever.
+	std::uint8_t knocks = 0;
+	std::uint32_t idle = 4000000;
+	while (knocks < 3) {
+		if (auto byte = serial.read())
+			knocks = *byte == '@' ? knocks + 1 : 0;
+		else if (--idle == 0)
+			appjump();
+	}
+
+	// Password gate: the config page holds it at app_end+3, terminated by 0xff.
+	// A blank page (0xff there) means no password. A wrong byte hangs the loader
+	// silently, as TSB does.
+	for (const std::uint8_t *pw = flash_ptr(app_end + 3); avr::flash_load(pw) != 0xff; ++pw)
+		if (rx() != avr::flash_load(pw))
+			for (;;) {
+			}
+
+	send_flash(reinterpret_cast<std::uint16_t>(info::storage.data()), info::size());
+
+	for (;;) {
+		tx(confirm); // Mainloop ready
+		switch (rx()) {
+		case 'f':
+			read_flash();
+			break;
+		case 'F':
+			write_flash();
+			break;
+		case 'e':
+			read_eeprom();
+			break;
+		case 'E':
+			write_eeprom();
+			break;
+		case 'c':
+			send_flash(app_end, page);
+			break;
+		case 'C':
+			write_config();
+			break;
+		default:
+			appjump(); // 'q' or any other byte runs the application
+		}
+	}
+}
+
+} // namespace tsb
+
+// Reset lands here: BOOTRST vectors to the boot section base and .vectors is
+// laid first, so this is the first instruction executed. No crt ran, so set the
+// stack pointer before anything is called.
+extern "C" [[gnu::naked, gnu::used, gnu::section(".vectors")]] void __boot_entry()
+{
+	SP = RAMEND;
+	tsb::run();
+}

tsb/tsb_tricks.cpp

@@ -0,0 +1,245 @@
+// TinySafeBoot on libavr — tier 2: C++ with compiler trickery.
+//
+// Same protocol and libavr surface as the pure variant (tsb_pure.cpp), but the
+// readable one-handler-per-command shape is traded for size: flash and EEPROM
+// share a single code path selected by a *runtime* flag decoded from the
+// command byte, so the compiler cannot constant-propagate it into two clones.
+// Attributes pin that sharing down (noinline/noclone) and the hot page pointer
+// and byte counter are pinned to call-saved registers to erase the prologue
+// push/pop that C++ function decomposition otherwise pays. No inline assembly.
+
+#include <libavr/libavr.hpp>
+
+#include <avr/io.h> // SP / RAMEND for the crt-free boot entry
+
+using namespace avr::literals;
+namespace spm = avr::spm;
+namespace ee = avr::eeprom;
+
+using dev = avr::device<{.clock = 16_MHz}>;
+using serial_t = dev::uart0<{.baud = 115200_Bd, .max_baud_error = 3_pct}>;
+inline constexpr serial_t serial{};
+
+namespace tsb {
+
+constexpr auto off = avr::irq::guard_policy::unused;
+
+constexpr std::uint8_t confirm = '!';
+constexpr std::uint8_t request = '?';
+
+constexpr std::uint16_t page = spm::page_bytes;
+constexpr std::uint16_t boot_bytes = 1024;
+constexpr std::uint16_t app_end = spm::flash_bytes - boot_bytes - page;
+constexpr std::uint16_t eeprom_end = avr::hw::db.mem.eeprom_size - 1;
+
+constexpr std::uint16_t build_date = 26 * 512 + 7 * 32 + 19;
+
+// clang-format off
+[[gnu::progmem]] constexpr std::uint8_t info[16] = {
+    'T', 'S', 'B',
+    build_date & 0xFF, build_date >> 8,
+    0xF3,
+    0x1E, 0x95, 0x0F,
+    page / 2,
+    (app_end / 2) & 0xFF, (app_end / 2) >> 8,
+    eeprom_end & 0xFF, eeprom_end >> 8,
+    0xAA, 0xAA,
+};
+// clang-format on
+
+[[gnu::section(".noinit")]] std::uint8_t buffer[page];
+
+// The hot page walk lives in call-saved global registers, TSB-style: g_addr is
+// the running flash/EEPROM byte address, g_cnt the byte countdown. Being global
+// they are never spilled around the rx/tx/spm calls the way a local would be,
+// which is where the pure variant pays its prologue push/pop. r4-r7 are
+// call-saved, so the library's UART/SPM helpers preserve them across calls.
+register std::uint16_t g_addr asm("r4");
+register std::uint8_t g_cnt asm("r6");
+
+std::uint8_t rx()
+{
+	for (;;)
+		if (auto byte = serial.read())
+			return *byte;
+}
+
+void tx(std::uint8_t byte)
+{
+	serial.write(byte);
+}
+
+const std::uint8_t *flash_ptr(std::uint16_t addr)
+{
+	return reinterpret_cast<const std::uint8_t *>(addr);
+}
+
+// One page transfer, memory selected at run time. noinline + noclone keep it a
+// single shared body: the `flash` flag arrives from the command byte, so the
+// optimiser cannot split it back into a flash copy and an EEPROM copy. All of
+// these walk g_addr / g_cnt, set by the caller.
+
+// Stream g_cnt bytes to the host from flash (LPM) or EEPROM, advancing g_addr
+// so a caller can send consecutive pages without re-seeding it.
+[[gnu::noinline, gnu::noclone]] void send(bool flash)
+{
+	do {
+		tx(flash ? avr::flash_load(flash_ptr(g_addr)) : ee::read(g_addr));
+		++g_addr;
+	} while (--g_cnt);
+}
+
+// Take one page from the host into the SRAM buffer.
+[[gnu::noinline]] void get_page()
+{
+	g_cnt = 0;
+	do {
+		buffer[g_cnt] = rx();
+	} while (++g_cnt != page);
+}
+
+[[gnu::noinline]] bool request_confirm()
+{
+	tx(request);
+	return rx() == confirm;
+}
+
+// Program the SRAM buffer into the already-erased page at g_addr (flash) or into
+// EEPROM. g_addr is left on the page base for the caller to advance.
+[[gnu::noinline, gnu::noclone]] void write_page(bool flash)
+{
+	g_cnt = 0;
+	if (flash) {
+		do {
+			spm::fill<off>(g_addr + g_cnt, static_cast<std::uint16_t>(buffer[g_cnt] | (buffer[g_cnt + 1] << 8)));
+			g_cnt += 2;
+		} while (g_cnt != page);
+		spm::write_page<off>(g_addr);
+		spm::wait();
+	} else {
+		do {
+			ee::write<off>(g_addr + g_cnt, buffer[g_cnt]);
+		} while (++g_cnt != page);
+	}
+}
+
+[[noreturn]] void appjump()
+{
+	spm::wait();
+	reinterpret_cast<void (*)()>(0)();
+	__builtin_unreachable();
+}
+
+// 'f'/'e': stream memory back one page per host '!'. send advances g_addr, so
+// flash self-terminates at the application boundary; EEPROM runs until the host
+// stops.
+[[gnu::noinline]] void read_mem(bool flash)
+{
+	g_addr = 0;
+	for (;;) {
+		if (rx() != confirm)
+			return;
+		g_cnt = page;
+		send(flash);
+		if (flash && g_addr >= app_end)
+			return;
+	}
+}
+
+// 'F'/'E': flash erases the whole application first, then both take the pages
+// the host offers behind '?'.
+[[gnu::noinline]] void write_mem(bool flash)
+{
+	if (flash) {
+		g_addr = 0;
+		do {
+			spm::erase_page<off>(g_addr);
+			spm::wait();
+			g_addr += page;
+		} while (g_addr < app_end);
+	}
+	g_addr = 0;
+	while (request_confirm()) {
+		get_page();
+		write_page(flash);
+		g_addr += page;
+	}
+	if (flash)
+		spm::rww_enable<off>();
+}
+
+// 'C': replace the config page, then echo it back for the host to verify.
+void write_config()
+{
+	if (!request_confirm())
+		return;
+	get_page();
+	g_addr = app_end;
+	spm::erase_page<off>(g_addr);
+	spm::wait();
+	write_page(true);
+	spm::rww_enable<off>();
+	g_cnt = page;
+	send(true); // g_addr is still app_end
+}
+
+[[noreturn]] void run()
+{
+	if (avr::hw::reg<"MCUSR">::read() & avr::hw::field<"MCUSR", "WDRF">{}(1).value)
+		appjump();
+
+	avr::init<serial_t>();
+
+	std::uint8_t knocks = 0;
+	std::uint32_t idle = 4000000;
+	while (knocks < 3) {
+		if (auto byte = serial.read())
+			knocks = *byte == '@' ? knocks + 1 : 0;
+		else if (--idle == 0)
+			appjump();
+	}
+
+	for (const std::uint8_t *pw = flash_ptr(app_end + 3); avr::flash_load(pw) != 0xff; ++pw)
+		if (rx() != avr::flash_load(pw))
+			for (;;) {
+			}
+
+	g_addr = reinterpret_cast<std::uint16_t>(&info[0]);
+	g_cnt = sizeof(info);
+	send(true);
+
+	for (;;) {
+		tx(confirm);
+		// Decode the command arithmetically so `flash`/`write` stay runtime
+		// values: bit 5 is the case bit (upper = write), and the folded-lower
+		// letter picks the memory. A single unified path serves f/F/e/E.
+		std::uint8_t cmd = rx();
+		std::uint8_t lower = cmd | 0x20;
+		bool write = (cmd & 0x20) == 0;
+		if (lower == 'f' || lower == 'e') {
+			bool flash = lower == 'f';
+			if (write)
+				write_mem(flash);
+			else
+				read_mem(flash);
+		} else if (lower == 'c') {
+			if (write) {
+				write_config();
+			} else {
+				g_addr = app_end;
+				g_cnt = page;
+				send(true);
+			}
+		} else {
+			appjump();
+		}
+	}
+}
+
+} // namespace tsb
+
+extern "C" [[gnu::naked, gnu::used, gnu::section(".vectors")]] void __boot_entry()
+{
+	SP = RAMEND;
+	tsb::run();
+}