76 lines
2 KiB
ArmAsm
Executable file
76 lines
2 KiB
ArmAsm
Executable file
! This is the C run-time start-off routine. It's job is to take the
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! arguments as put on the stack by EXEC, and to parse them and set them up the
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! way _main expects them.
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! It also initializes _environ when this variable isn't defined by the
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! programmer. The detection of whether _environ belong to us is rather
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! simplistic. We simply check for some magic value, but there is no other
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! way.
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.sect .text; .sect .rom; .sect .data; .sect .bss
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.define begtext, begdata, begbss
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.sect .text
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begtext:
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.sect .rom
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begrom:
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.sect .data
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begdata:
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.sect .bss
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begbss:
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.define crtso, ___main, __penviron, __penvp, __fpu_present
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.extern _main, _exit
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.sect .text
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crtso:
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xor ebp, ebp ! clear for backtrace of core files
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mov eax, (esp) ! argc
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lea edx, 4(esp) ! argv
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lea ecx, 8(esp)(eax*4) ! envp
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! Test if environ is in the initialized data area and is set to our
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! magic number. If so then it is not redefined by the user.
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mov ebx, _environ
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cmp ebx, __edata ! within initialized data?
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jae 0f
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testb bl, 3 ! aligned?
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jnz 0f
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cmp (ebx), 0x53535353 ! is it our _environ?
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jne 0f
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mov (__penviron), ebx ! _penviron = &environ;
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0: mov ebx, (__penviron)
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mov (ebx), ecx ! *_penviron = envp;
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push ecx ! push envp
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push edx ! push argv
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push eax ! push argc
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! Test the EM bit of the MSW to determine if an FPU is present and
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! set __fpu_present if one is found.
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smsw ax
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testb al, 0x4 ! EM bit in MSW
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setz (__fpu_present) ! True if not set
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call _main ! main(argc, argv, envp)
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push eax ! push exit status
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call _exit
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hlt ! force a trap if exit fails
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___main: ! for GCC
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ret
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.sect .rom
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.data4 0 ! Separate I&D: *NULL == 0
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! Also keeps the first string in the
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! program from appearing at location 0!
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.sect .data
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__penviron:
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.data4 __penvp ! Pointer to environ, or hidden pointer
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.sect .bss
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.comm __penvp, 4 ! Hidden environment vector
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.comm __fpu_present, 4 ! FPU present flag
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.extern endtext ! Force loading of end labels.
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