# Asserts the autobaud loader's measured unit sits where the host will read
# it (--info's measured clock — the address is wire contract). Two homes: on
# a chip with the GPIOR pair the unit lives there and the image must carry no
# RAM word for it at all; elsewhere it is the first RAM object at SRAM start.
# Run as
#   cmake -DOBJDUMP=... -DELF=... -DRAM_START=<data address> [-DGPIOR=<data address>]
#         -P check_unit.cmake

execute_process(COMMAND ${OBJDUMP} -t ${ELF} OUTPUT_VARIABLE _syms RESULT_VARIABLE _res)
if(NOT _res EQUAL 0)
	message(FATAL_ERROR "${OBJDUMP} -t ${ELF} failed")
endif()

# The symbol line: "00800100 l     O .noinit  00000002 <mangled>unit_E".
string(REGEX MATCH "\n0*([0-9a-f]+)[^\n]+[ \t][^ \t\n]*unit_E\n" _line "${_syms}")

if(GPIOR)
	if(_line)
		message(FATAL_ERROR "unit_ RAM symbol present although the unit's home is GPIOR ${GPIOR} — "
		                    "the host peeks the pair, and a RAM copy would be dead weight")
	endif()
	message(STATUS "no unit_ RAM object — the unit lives in the GPIOR pair at ${GPIOR}")
	return()
endif()

if(NOT _line)
	message(FATAL_ERROR "no unit_ symbol in ${ELF} — is this the autobaud loader?")
endif()

# AVR data-space symbols carry the 0x800000 VMA offset.
math(EXPR _want "0x800000 + ${RAM_START}" OUTPUT_FORMAT HEXADECIMAL)
math(EXPR _have "0x${CMAKE_MATCH_1}" OUTPUT_FORMAT HEXADECIMAL)
if(NOT _have STREQUAL _want)
	message(FATAL_ERROR "unit_ sits at ${_have}, ram_start is ${_want} — the host peeks ram_start")
endif()
message(STATUS "unit_ at ${_have} == ram_start")