42 lines
884 B
ArmAsm
42 lines
884 B
ArmAsm
! strchr() Author: Kees J. Bot
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! 1 Jan 1994
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.sect .text; .sect .rom; .sect .data; .sect .bss
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! char *strchr(const char *s, int c)
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! Look for a character in a string.
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!
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.sect .text
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.define _strchr
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.align 16
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_strchr:
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push ebp
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mov ebp, esp
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push edi
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cld
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mov edi, 8(ebp) ! edi = string
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mov edx, 16 ! Look at small chunks of the string
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next: shl edx, 1 ! Chunks become bigger each time
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mov ecx, edx
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xorb al, al ! Look for the zero at the end
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repne
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scasb
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pushf ! Remember the flags
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sub ecx, edx
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neg ecx ! Some or all of the chunk
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sub edi, ecx ! Step back
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movb al, 12(ebp) ! The character to look for
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repne
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scasb
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je found
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popf ! Did we find the end of string earlier?
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jne next ! No, try again
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xor eax, eax ! Return NULL
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pop edi
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pop ebp
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ret
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found: pop eax ! Get rid of those flags
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lea eax, -1(edi) ! Address of byte found
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pop edi
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pop ebp
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ret
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