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Diffstat (limited to 'private/crt32/string/i386/strcmp.asm')
| -rw-r--r-- | private/crt32/string/i386/strcmp.asm | 104 |
1 files changed, 104 insertions, 0 deletions
diff --git a/private/crt32/string/i386/strcmp.asm b/private/crt32/string/i386/strcmp.asm new file mode 100644 index 000000000..6024848b5 --- /dev/null +++ b/private/crt32/string/i386/strcmp.asm @@ -0,0 +1,104 @@ + page ,132 + title strcmp.asm - compare two strings +;*** +;strcmp.asm - routine to compare two strings (for equal, less, or greater) +; +; Copyright (c) 1985-1991, Microsoft Corporation. All rights reserved. +; +;Purpose: +; STRCMP compares two strings and returns an integer +; to indicate whether the first is less than the second, the two are +; equal, or whether the first is greater than the second, respectively. +; Comparison is done byte by byte on an UNSIGNED basis, which is to +; say that Null (0) is less than any other character (1-255). +; +;Revision History: +; 04-21-87 SKS Module rewritten to be fast and small +; 05-17-88 SJM Add model-independent (large model) ifdef +; 08-04-88 SJM convert to cruntime/ add 32-bit support +; 08-23-88 JCR Minor 386 cleanup +; 10-25-88 JCR General cleanup for 386-only code +; 03-23-90 GJF Changed to _stdcall. Also, fixed the copyright. +; 05-10-91 GJF Back to _cdecl, sigh... +; +;******************************************************************************* + + .xlist + include cruntime.inc + .list + +page +;*** +;strcmp - compare two strings, returning less than, equal to, or greater than +; +;Purpose: +; Compares two string, determining their lexical order. Unsigned +; comparison is used. +; +; Algorithm: +; int strcmp ( src , dst ) +; unsigned char *src; +; unsigned char *dst; +; { +; int ret = 0 ; +; +; while( ! (ret = *src - *dst) && *dst) +; ++src, ++dst; +; +; if ( ret < 0 ) +; ret = -1 ; +; else if ( ret > 0 ) +; ret = 1 ; +; +; return( ret ); +; } +; +;Entry: +; const char * src - string for left-hand side of comparison +; const char * dst - string for right-hand side of comparison +; +;Exit: +; AX < 0, 0, or >0, indicating whether the first string is +; Less than, Equal to, or Greater than the second string. +; +;Uses: +; CX, DX +; +;Exceptions: +; +;******************************************************************************* + + CODESEG + + .lall + + public strcmp +strcmp proc \ + uses edi esi, \ + src:ptr byte, \ + dst:ptr byte + + + mov esi,[src] ; si = source + xor eax,eax ; mingle register instr with mem instr. + mov edi,[dst] ; di = dest + + or ecx,-1 ; cx = -1 + repne scasb ; compute length of "dst" + not ecx ; CX = strlen(dst)+1 + sub edi,ecx ; restore DI = dst + repe cmpsb ; compare while equal, at most length of "dst" + je short toend ; dst == src? (AX = 0) + ; dst < src dst > src + sbb eax,eax ; AX=-1, CY=1 AX=0, CY=0 + sbb eax,-1 ; AX=-1 AX=1 +toend: + +ifdef _STDCALL_ + ret 2*DPSIZE ; _stdcall return +else + ret ; _cdecl return +endif + +strcmp endp + end |