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/* Vector optimized 32/64 bit S/390 version of memrchr.
Copyright (C) 2015-2016 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#if defined HAVE_S390_VX_ASM_SUPPORT && IS_IN (libc)
# include "sysdep.h"
# include "asm-syntax.h"
.text
/* void *memrchr (const void *s, int c, size_t n)
Scans memory for character c backwards
and returns pointer to first c.
Register usage:
-r0=tmp
-r1=tmp
-r2=s
-r3=c
-r4=n
-r5=s in loop
-v16=part of s
-v17=index of found c
-v18=c replicated
-v20=permute pattern
*/
ENTRY(__memrchr_vx)
.machine "z13"
.machinemode "zarch_nohighgprs"
# if !defined __s390x__
llgfr %r4,%r4
# endif /* !defined __s390x__ */
clgije %r4,0,.Lnot_found
vlvgb %v18,%r3,0 /* Generate vector which elements are all c.
If c > 255, c will be truncated. */
vrepb %v18,%v18,0
llcr %r3,%r3 /* char c_char = (char) c. */
/* check byte n - 1. */
llc %r0,-1(%r4,%r2)
slgfi %r4,1
clrje %r0,%r3,.Lfound_end
jh .Lnot_found /* Return NULL if n is now 0. */
larl %r1,.Lpermute_mask /* Load permute mask. */
vl %v20,0(%r1)
/* check byte n - 2. */
llc %r0,-1(%r4,%r2)
slgfi %r4,1
clrje %r0,%r3,.Lfound_end
jh .Lnot_found /* Return NULL if n is now 0. */
clgijhe %r4,64,.Lloop64 /* If n >= 64 -> loop64. */
.Llt64:
/* Process n < 64 bytes. */
clgijl %r4,16,.Llt16 /* Jump away if n < 16. */
aghi %r4,-16
vl %v16,0(%r4,%r2)
vfeebs %v17,%v16,%v18
jno .Lfound0
clgijl %r4,16,.Llt16
aghi %r4,-16
vl %v16,0(%r4,%r2)
vfeebs %v17,%v16,%v18
jno .Lfound0
clgijl %r4,16,.Llt16
aghi %r4,-16
vl %v16,0(%r4,%r2)
vfeebs %v17,%v16,%v18
jno .Lfound0
.Llt16:
clgfi %r4,0 /* if remaining bytes == 0, return NULL. */
locghie %r2,0
ber %r14
aghi %r4,-1 /* vll needs highest index. */
vll %v16,%r4,0(%r2) /* Load remaining bytes. */
/* Right-shift of v16 to mask bytes after highest index. */
lhi %r0,15
slr %r0,%r4 /* Compute byte count for vector shift right. */
sll %r0,3 /* Convert to bit count. */
vlvgb %v17,%r0,7
vsrlb %v16,%v16,%v17 /* Vector shift right by byte by number of bytes
specified in bits 1-4 of byte 7 in v17. */
j .Lfound_permute
.Lfound48:
aghi %r4,16
.Lfound32:
aghi %r4,16
.Lfound16:
aghi %r4,16
.Lfound0:
la %r2,0(%r4,%r2) /* Set pointer to start of v16. */
lghi %r4,15 /* Set highest index in v16 to last index. */
.Lfound_permute:
/* Search for a c in v16 in reversed byte order. v16 contains %r4 + 1
bytes. If v16 was not fully loaded, the bytes are already
right shifted, so that the bytes in v16 can simply be reversed. */
vperm %v16,%v16,%v16,%v20 /* Permute v16 to reversed order. */
vfeeb %v16,%v16,%v18 /* Find c in reversed v16. */
vlgvb %r1,%v16,7 /* Index of c or 16 if not found. */
/* Return NULL if there is no c in loaded bytes. */
clrjh %r1,%r4,.Lnot_found
slgr %r4,%r1
.Lfound_end:
la %r2,0(%r4,%r2) /* Return pointer to c. */
br %r14
.Lnot_found:
lghi %r2,0
br %r14
.Lpermute_mask:
.byte 0x0F,0x0E,0x0D,0x0C,0x0B,0x0A,0x09,0x08
.byte 0x07,0x06,0x05,0x04,0x03,0x02,0x01,0x00
.Lloop64:
aghi %r4,-64
vl %v16,48(%r4,%r2) /* Load 16bytes of memory area. */
vfeebs %v17,%v16,%v18 /* Find c. */
jno .Lfound48 /* Jump away if c was found. */
vl %v16,32(%r4,%r2)
vfeebs %v17,%v16,%v18
jno .Lfound32
vl %v16,16(%r4,%r2)
vfeebs %v17,%v16,%v18
jno .Lfound16
vl %v16,0(%r4,%r2)
vfeebs %v17,%v16,%v18
jno .Lfound0
clgijhe %r4,64,.Lloop64 /* If n >= 64 -> loop64. */
j .Llt64
END(__memrchr_vx)
#endif /* HAVE_S390_VX_ASM_SUPPORT && IS_IN (libc) */
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