BlackMark
8f6319c068
Four cuts, none touching what the loader can do. The entry stub stops re-doing the reset logic's own SP write where the datasheet guarantees RAMEND (stack::hardware — the classic megas keep theirs). The autobaud unit moves into GPIOR2:GPIOR1 wherever the chip has the pair: one-word accesses, no RAM object, and the host's measured-clock peek follows it by version and geometry. 'J' rides the unified decode, carrying a selector it ignores so its address is the same two reads as every other command — the tool sends the bare form to older residents. run_app stops insisting on a body of its own. The fleet lands at 358–410 B stock and 438–474 B autobaud; the tightest image in the space — the 1284s' autobaud on a USART's own pins with the OSCCAL trim — drops from 510 to 484 of its 512. Every chip's suite is green on the wire that changed, and the README's table is machine-checked against the built images. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
37 lines
1.5 KiB
CMake
37 lines
1.5 KiB
CMake
# Asserts the autobaud loader's measured unit sits where the host will read
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# it (--info's measured clock — the address is wire contract). Two homes: on
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# a chip with the GPIOR pair the unit lives there and the image must carry no
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# RAM word for it at all; elsewhere it is the first RAM object at SRAM start.
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# Run as
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# cmake -DOBJDUMP=... -DELF=... -DRAM_START=<data address> [-DGPIOR=<data address>]
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# -P check_unit.cmake
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execute_process(COMMAND ${OBJDUMP} -t ${ELF} OUTPUT_VARIABLE _syms RESULT_VARIABLE _res)
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if(NOT _res EQUAL 0)
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message(FATAL_ERROR "${OBJDUMP} -t ${ELF} failed")
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endif()
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# The symbol line: "00800100 l O .noinit 00000002 <mangled>unit_E".
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string(REGEX MATCH "\n0*([0-9a-f]+)[^\n]+[ \t][^ \t\n]*unit_E\n" _line "${_syms}")
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if(GPIOR)
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if(_line)
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message(FATAL_ERROR "unit_ RAM symbol present although the unit's home is GPIOR ${GPIOR} — "
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"the host peeks the pair, and a RAM copy would be dead weight")
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endif()
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message(STATUS "no unit_ RAM object — the unit lives in the GPIOR pair at ${GPIOR}")
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return()
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endif()
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if(NOT _line)
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message(FATAL_ERROR "no unit_ symbol in ${ELF} — is this the autobaud loader?")
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endif()
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# AVR data-space symbols carry the 0x800000 VMA offset.
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math(EXPR _want "0x800000 + ${RAM_START}" OUTPUT_FORMAT HEXADECIMAL)
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math(EXPR _have "0x${CMAKE_MATCH_1}" OUTPUT_FORMAT HEXADECIMAL)
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if(NOT _have STREQUAL _want)
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message(FATAL_ERROR "unit_ sits at ${_have}, ram_start is ${_want} — the host peeks ram_start")
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endif()
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message(STATUS "unit_ at ${_have} == ram_start")
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