minix/common/lib/libc/arch/i386/string/strcmp.S
Gianluca Guida b6cbf7203b Import unmodified NetBSD libc in trunk
This patch imports the unmodified current version of NetBSD libc.
The NetBSD includes are in /nbsd_include, while the libc code itself is 
split between lib/nbsd_libc and common/lib/libc.
2011-02-14 19:36:03 +00:00

77 lines
1.1 KiB
ArmAsm

/*
* Written by J.T. Conklin <jtc@acorntoolworks.com>
* Public domain.
*/
#include <machine/asm.h>
#if defined(LIBC_SCCS)
RCSID("$NetBSD: strcmp.S,v 1.1 2005/12/20 19:28:49 christos Exp $")
#endif
ENTRY(strcmp)
pushl %esi
pushl %ebx
movl 12(%esp),%ebx
movl 16(%esp),%esi
/*
* Align s1 to word boundary.
* Consider unrolling loop?
*/
.Ls1align:
testb $3,%bl
je .Ls1aligned
movb (%ebx),%al
incl %ebx
movb (%esi),%dl
incl %esi
testb %al,%al
je .Ldone
cmpb %al,%dl
je .Ls1align
jmp .Ldone
/*
* Check whether s2 is aligned to a word boundary. If it is, we
* can compare by words. Otherwise we have to compare by bytes.
*/
.Ls1aligned:
testl $3,%esi
jne .Lbyte_loop
subl $4,%ebx
subl $4,%esi
_ALIGN_TEXT
.Lword_loop:
movl 4(%ebx),%eax
addl $4,%ebx
movl 4(%esi),%edx
addl $4,%esi
cmpl %eax,%edx
jne .Lbyte_loop
subl $0x01010101,%edx
notl %eax
andl %eax,%edx
testl $0x80808080,%edx
je .Lword_loop
_ALIGN_TEXT
.Lbyte_loop:
movb (%ebx),%al
incl %ebx
movb (%esi),%dl
incl %esi
testb %al,%al
je .Ldone
cmpb %al,%dl
je .Lbyte_loop
.Ldone:
movzbl %al,%eax
movzbl %dl,%edx
subl %edx,%eax
popl %ebx
popl %esi
ret