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