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| [9] | 1 | ! strchr() Author: Kees J. Bot
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| 2 | ! 1 Jan 1994
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| 3 | .sect .text; .sect .rom; .sect .data; .sect .bss
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| 4 |
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| 5 | ! char *strchr(const char *s, int c)
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| 6 | ! Look for a character in a string.
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| 7 | !
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| 8 | .sect .text
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| 9 | .define _strchr
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| 10 | .align 16
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| 11 | _strchr:
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| 12 | push ebp
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| 13 | mov ebp, esp
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| 14 | push edi
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| 15 | cld
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| 16 | mov edi, 8(ebp) ! edi = string
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| 17 | mov edx, 16 ! Look at small chunks of the string
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| 18 | next: shl edx, 1 ! Chunks become bigger each time
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| 19 | mov ecx, edx
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| 20 | xorb al, al ! Look for the zero at the end
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| 21 | repne
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| 22 | scasb
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| 23 | pushf ! Remember the flags
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| 24 | sub ecx, edx
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| 25 | neg ecx ! Some or all of the chunk
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| 26 | sub edi, ecx ! Step back
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| 27 | movb al, 12(ebp) ! The character to look for
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| 28 | repne
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| 29 | scasb
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| 30 | je found
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| 31 | popf ! Did we find the end of string earlier?
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| 32 | jne next ! No, try again
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| 33 | xor eax, eax ! Return NULL
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| 34 | pop edi
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| 35 | pop ebp
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| 36 | ret
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| 37 | found: pop eax ! Get rid of those flags
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| 38 | lea eax, -1(edi) ! Address of byte found
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| 39 | pop edi
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| 40 | pop ebp
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| 41 | ret
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