/* 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, see <http://www.gnu.org/licenses/>. */ /* 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)