NetBSD/lib/libc/arch/ns32k/string/strrchr.S

141 lines
3.1 KiB
ArmAsm

/* $NetBSD: strrchr.S,v 1.3 1998/04/03 22:58:10 matthias Exp $ */
/*
* Written by Matthias Pfaller, 1996
* Public domain.
*/
#include <machine/asm.h>
#if defined(LIBC_SCCS)
RCSID("$NetBSD: strrchr.S,v 1.3 1998/04/03 22:58:10 matthias Exp $")
# if defined(RINDEX)
RCSID("$Masqueraded: as rindex $")
# endif
#endif
#if !defined(RINDEX)
/*
* char *
* strrchr (const char *s, int c)
* locate the last occurrence of c in the string s.
*/
KENTRY(strrchr, 8)
#else
/*
* char *
* rindex (const char *s, int c)
* locate the last occurrence of c in the string s.
*/
KENTRY(rindex, 8)
#endif
enter [r3,r4,r5,r6,r7],0
movd B_ARG0,r0
movzbd B_ARG1,r1
movd 0x01010101,r5
movqd 0,r6
muld r1,r5
/*
* First begin by seeing if we can doubleword align the
* pointer. The following code aligns the pointer in r0.
*/
movqd 3,r3
andd r0,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 r5,0(r0) ; bne 0f ; movd r0,r6 ; 0: cmpqb 0,0(r0) ; beq 8f
cmpb r5,1(r0) ; bne 0f ; movd r0,r6 ; 0: cmpqb 0,1(r0) ; beq 8f
cmpb r5,2(r0) ; bne 0f ; movd r0,r6 ; 0: cmpqb 0,2(r0) ; beq 8f
addqd 3,r0
br 5f
.align 2,0xa2
3: cmpb r5,0(r0) ; bne 0f ; movd r0,r6 ; 0: cmpqb 0,0(r0) ; beq 8f
cmpb r5,1(r0) ; bne 0f ; movd r0,r6 ; 0: cmpqb 0,1(r0) ; beq 8f
addqd 2,r0
br 5f
.align 2,0xa2
4: cmpb r5,0(r0) ; bne 0f ; movd r0,r6 ; 0: cmpqb 0,0(r0) ; beq 8f
addqd 1,r0
/*
* Okay, when we get down here r0 points at a double word
* algined source block of bytes.
* 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,r2 /* Magic number to use */
movd 0x80808080,r3 /* Another magic number. */
addqd -4,r0
br 1f
.align 2,0xa2
0: movd r4,r1
subd r2,r1 /* Gets borrow if byte = 0. */
bicd r4,r1 /* Clear original bits. */
andd r3,r1 /* See if borrow occurred. */
cmpqd 0,r1
bne 8f /* See if this DWORD contained a 0. */
1: movd 4(r0),r4 /* Get next double word. */
addd 4,r0 /* Advance pointer */
xord r5,r4 /* Convert any 'c' to 0. */
movd r4,r1
subd r2,r1
bicd r4,r1
andd r3,r1
xord r5,r4
cmpqd 0,r1
beq 0b
movd r6,r7
movd r0,r6
br 0b
/*
* At this point, r6 points at a double word which
* contains c or r6 is zero.
*/
8: movqd 0,r0
9: cmpqd 0,r6
beq 2f
cmpb r5,0(r6) ; bne 0f ; movd r6,r0 ; 0: cmpqb 0,0(r6) ; beq 1f
cmpb r5,1(r6) ; bne 0f ; addr 1(r6),r0 ; 0: cmpqb 0,1(r6) ; beq 1f
cmpb r5,2(r6) ; bne 0f ; addr 2(r6),r0 ; 0: cmpqb 0,2(r6) ; beq 1f
cmpb r5,3(r6) ; bne 1f ; addr 3(r6),r0 ; 1: cmpqd 0,r0 ; bne 2f
/*
* Maybe the last match was behind the end of the string.
*/
movd r7,r6
br 9b
2: exit [r3,r4,r5,r6,r7]
ret ARGS