132 lines
3.1 KiB
ArmAsm
132 lines
3.1 KiB
ArmAsm
/* $NetBSD: strcmp.S,v 1.2 1997/05/08 13:38:56 matthias Exp $ */
|
|
|
|
/*
|
|
* Written by Randy Hyde, 1993
|
|
* Public domain.
|
|
*/
|
|
|
|
#include <machine/asm.h>
|
|
|
|
#if defined(LIBC_SCCS)
|
|
RCSID("$NetBSD: strcmp.S,v 1.2 1997/05/08 13:38:56 matthias Exp $")
|
|
#endif
|
|
|
|
/*
|
|
* int
|
|
* strcmp (const char *s1, const char *s2)
|
|
* compare strings s1 and s2.
|
|
*/
|
|
|
|
ENTRY(strcmp)
|
|
enter [r3,r4,r5],0
|
|
movd B_ARG1,r1
|
|
movd B_ARG0,r2
|
|
|
|
/*
|
|
* First begin by seeing if we can doubleword align the
|
|
* pointers. The following code only aligns the pointer in R1.
|
|
* If the L.O. two bits of R2 do not match, it's going to run
|
|
* slower but there is nothing we can do about that. Better to
|
|
* have at least one of them double word aligned rather than
|
|
* neither.
|
|
*/
|
|
|
|
movqd 3,r3
|
|
andd r1,r3
|
|
|
|
0: casew 1f(pc)[r3:w]
|
|
1: .word 5f-0b
|
|
.word 2f-0b
|
|
.word 3f-0b
|
|
.word 4f-0b
|
|
|
|
.align 2,0xa2
|
|
2: cmpb 0(r1),0(r2) ; bne 8f ; cmpqb 0,0(r1) ; beq 9f
|
|
cmpb 1(r1),1(r2) ; bne 8f ; cmpqb 0,1(r1) ; beq 9f
|
|
cmpb 2(r1),2(r2) ; bne 8f ; cmpqb 0,2(r1) ; beq 9f
|
|
addqd 3,r1
|
|
addqd 3,r2
|
|
br 5f
|
|
|
|
.align 2,0xa2
|
|
3: cmpb 0(r1),0(r2) ; bne 8f ; cmpqb 0,0(r1) ; beq 9f
|
|
cmpb 1(r1),1(r2) ; bne 8f ; cmpqb 0,1(r1) ; beq 9f
|
|
addqd 2,r1
|
|
addqd 2,r2
|
|
br 5f
|
|
|
|
.align 2,0xa2
|
|
4: cmpb 0(r1),0(r2) ; bne 8f ; cmpqb 0,0(r1) ; beq 9f
|
|
addqd 1,r1
|
|
addqd 1,r2
|
|
|
|
/*
|
|
* Okay, when we get down here R1 points at a double word
|
|
* algined source block of bytes, R2 points at another block of
|
|
* bytes (typically, though not always double word aligned).
|
|
* This guy processes four bytes at a time and checks for the
|
|
* zero terminating byte amongst the bytes in the double word.
|
|
* This algorithm is de to Dave Rand.
|
|
*
|
|
* Sneaky test for zero amongst four bytes:
|
|
*
|
|
* xxyyzztt
|
|
* -01010101
|
|
* ---------
|
|
* aabbccdd
|
|
* bic xxyyzztt
|
|
* ---------
|
|
* eeffgghh ee=0x80 if xx=0, ff=0x80 if yy=0, etc.
|
|
*
|
|
* This whole result will be zero if there
|
|
* was no zero byte, it will be non-zero if
|
|
* there is a zero byte present.
|
|
*/
|
|
|
|
5: movd 0x01010101,r3 /* Magic number to use */
|
|
movd 0x80808080,r4 /* Another magic number. */
|
|
|
|
movd 0(r1),r5 /* Get 1st double word. */
|
|
movd r5,r0 /* Save for storage later. */
|
|
subd r3,r0 /* Gets borrow if byte = 0. */
|
|
bicd r5,r0 /* Clear original bits. */
|
|
andd r4,r0 /* See if borrow occurred. */
|
|
cmpqd 0,r0
|
|
bne 1f /* If this DWORD contained a 0. */
|
|
|
|
.align 2,0xa2
|
|
0: movd 4(r1),r0 /* Get next 4 bytes to process */
|
|
cmpd r5,0(r2) /* Compare prev four bytes. */
|
|
bne 1f
|
|
addqd 4,r1
|
|
addqd 4,r2
|
|
movd r0,r5 /* Save for storage if no zeros. */
|
|
subd r3,r0
|
|
bicd r5,r0
|
|
andd r4,r0
|
|
cmpqd 0,r0
|
|
beq 0b
|
|
|
|
/*
|
|
* At this point either the strings are not equal or
|
|
* they contain a zero byte. Check them.
|
|
*/
|
|
|
|
1: cmpb 0(r1),0(r2) ; bne 8f ; cmpqb 0,0(r1) ; beq 9f
|
|
cmpb 1(r1),1(r2) ; bne 8f ; cmpqb 0,1(r1) ; beq 9f
|
|
cmpb 2(r1),2(r2) ; bne 8f ; cmpqb 0,2(r1) ; beq 9f
|
|
cmpb 3(r1),3(r2) ; bne 8f
|
|
|
|
9: movqd 0,r0
|
|
exit [r3,r4,r5]
|
|
ret 0
|
|
|
|
8: blo 0f /* Operands were reversed on cmp. */
|
|
movqd -1,r0 /* It's >, so return one. */
|
|
exit [r3,r4,r5]
|
|
ret 0
|
|
|
|
0: movqd 1,r0 /* It's <, so return -1. */
|
|
exit [r3,r4,r5]
|
|
ret 0
|