diff options
Diffstat (limited to 'newlib/libc/machine/i386/memcmp.S')
| -rw-r--r-- | newlib/libc/machine/i386/memcmp.S | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/newlib/libc/machine/i386/memcmp.S b/newlib/libc/machine/i386/memcmp.S new file mode 100644 index 0000000..23419dd --- /dev/null +++ b/newlib/libc/machine/i386/memcmp.S @@ -0,0 +1,75 @@ +/* + * ==================================================== + * Copyright (C) 1998 by Cygnus Solutions. All rights reserved. + * + * Permission to use, copy, modify, and distribute this + * software is freely granted, provided that this notice + * is preserved. + * ==================================================== + */ + + #include "i386mach.h" + + .global SYM (memcmp) + +SYM (memcmp): + + pushl ebp + movl esp,ebp + subl $16,esp + pushl ebx + pushl edi + pushl esi + movl 8(ebp),edi + movl 12(ebp),esi + movl 16(ebp),ecx + cld + +/* check if length is zero in which case just return 0 */ + + xorl eax,eax + testl ecx,ecx + jz L4 + +#ifndef __OPTIMIZE_SIZE__ + +/* if aligned on long boundary, compare doublewords at a time first */ + + movl edi,eax + orl esi,eax + testb $3,al + jne BYTECMP + movl ecx,ebx + shrl $2,ecx /* calculate number of long words to compare */ + repz + cmpsl + jz L5 + subl $4,esi + subl $4,edi + movl $4,ecx + jmp BYTECMP +L5: + andl $3,ebx /* calculate number of remaining bytes */ + movl ebx,ecx + +#endif /* not __OPTIMIZE_SIZE__ */ + +BYTECMP: /* compare any unaligned bytes or remainder bytes */ + repz + cmpsb + +/* set output to be < 0 if less than, 0 if equal, or > 0 if greater than */ +L3: + xorl edx,edx + movb -1(esi),dl + xorl eax,eax + movb -1(edi),al + subl edx,eax + +L4: + leal -28(ebp),esp + popl esi + popl edi + popl ebx + leave + ret |