35 lines
711 B
ArmAsm
35 lines
711 B
ArmAsm
! strncmp() 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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! int strncmp(const char *s1, const char *s2, size_t ecx)
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! Compare two strings.
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!
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.sect .text
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.define __strncmp
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.align 16
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__strncmp:
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push ebp
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mov ebp, esp
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push esi
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push edi
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test ecx, ecx ! Max length is zero?
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je done
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mov esi, 8(ebp) ! esi = string s1
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mov edi, 12(ebp) ! edi = string s2
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cld
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compare:
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cmpsb ! Compare two bytes
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jne done
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cmpb -1(esi), 0 ! End of string?
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je done
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dec ecx ! Length limit reached?
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jne compare
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done: seta al ! al = (s1 > s2)
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setb ah ! ah = (s1 < s2)
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subb al, ah
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movsxb eax, al ! eax = (s1 > s2) - (s1 < s2), i.e. -1, 0, 1
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pop edi
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pop esi
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pop ebp
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ret
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