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- /* Optimized version of the standard memchr() function.
- This file is part of the GNU C Library.
- Copyright (C) 2000, 2001, 2003 Free Software Foundation, Inc.
- Contributed by Dan Pop <Dan.Pop@cern.ch>.
- 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, write to the Free
- Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
- 02111-1307 USA. */
- /* Return: the address of the first occurence of chr in str or NULL
- Inputs:
- in0: str
- in1: chr
- in2: byte count
- This implementation assumes little endian mode. For big endian mode,
- the instruction czx1.r should be replaced by czx1.l.
- The algorithm is fairly straightforward: search byte by byte until we
- we get to a word aligned address, then search word by word as much as
- possible; the remaining few bytes are searched one at a time.
- The word by word search is performed by xor-ing the word with a word
- containing chr in every byte. If there is a hit, the result will
- contain a zero byte in the corresponding position. The presence and
- position of that zero byte is detected with a czx instruction.
- All the loops in this function could have had the internal branch removed
- if br.ctop and br.cloop could be predicated :-(. */
- #include "sysdep.h"
- #undef ret
- #define saved_pr r15
- #define saved_lc r16
- #define chr r17
- #define len r18
- #define pos0 r20
- #define val r21
- #define tmp r24
- #define chrx8 r25
- #define loopcnt r30
- #define str in0
- ENTRY(__memchr)
- .prologue
- alloc r2 = ar.pfs, 3, 0, 29, 32
- #include "softpipe.h"
- .rotr value[MEMLAT+1], addr[MEMLAT+3], aux[2], poschr[2]
- .rotp p[MEMLAT+3]
- .save ar.lc, saved_lc
- mov saved_lc = ar.lc /* save the loop counter */
- .save pr, saved_pr
- mov saved_pr = pr /* save the predicates */
- .body
- mov ret0 = str
- and tmp = 7, str /* tmp = str % 8 */
- cmp.ne p7, p0 = r0, r0 /* clear p7 */
- extr.u chr = in1, 0, 8 /* chr = (unsigned char) in1 */
- mov len = in2
- cmp.gtu p6, p0 = 16, in2 /* use a simple loop for short */
- (p6) br.cond.spnt .srchfew ;; /* searches */
- sub loopcnt = 8, tmp /* loopcnt = 8 - tmp */
- cmp.eq p6, p0 = tmp, r0
- (p6) br.cond.sptk .str_aligned;;
- sub len = len, loopcnt
- adds loopcnt = -1, loopcnt;;
- mov ar.lc = loopcnt
- .l1:
- ld1 val = [ret0], 1
- ;;
- cmp.eq p6, p0 = val, chr
- (p6) br.cond.spnt .foundit
- br.cloop.sptk .l1 ;;
- .str_aligned:
- cmp.ne p6, p0 = r0, r0 /* clear p6 */
- shr.u loopcnt = len, 3 /* loopcnt = len / 8 */
- and len = 7, len ;; /* remaining len = len & 7 */
- adds loopcnt = -1, loopcnt
- mov ar.ec = MEMLAT + 3
- mux1 chrx8 = chr, @brcst ;; /* get a word full of chr */
- mov ar.lc = loopcnt
- mov pr.rot = 1 << 16 ;;
- .l2:
- (p[0]) mov addr[0] = ret0
- (p[0]) ld8 value[0] = [ret0], 8
- (p[MEMLAT]) xor aux[0] = value[MEMLAT], chrx8
- (p[MEMLAT+1]) czx1.r poschr[0] = aux[1]
- (p[MEMLAT+2]) cmp.ne p7, p0 = 8, poschr[1]
- (p7) br.cond.dpnt .foundit
- br.ctop.dptk .l2
- .srchfew:
- adds loopcnt = -1, len
- cmp.eq p6, p0 = len, r0
- (p6) br.cond.spnt .notfound ;;
- mov ar.lc = loopcnt
- .l3:
- ld1 val = [ret0], 1
- ;;
- cmp.eq p6, p0 = val, chr
- (p6) br.cond.dpnt .foundit
- br.cloop.sptk .l3 ;;
- .notfound:
- cmp.ne p6, p0 = r0, r0 /* clear p6 (p7 was already 0 when we got here) */
- mov ret0 = r0 ;; /* return NULL */
- .foundit:
- .pred.rel "mutex" p6, p7
- (p6) adds ret0 = -1, ret0 /* if we got here from l1 or l3 */
- (p7) add ret0 = addr[MEMLAT+2], poschr[1] /* if we got here from l2 */
- mov pr = saved_pr, -1
- mov ar.lc = saved_lc
- br.ret.sptk.many b0
- END(__memchr)
- weak_alias(__memchr, memchr)
- weak_alias(__memchr, __ubp_memchr)
- libc_hidden_def(memchr)
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