1 /* Optimized version of the standard memchr() function.
2 This file is part of the GNU C Library.
3 Copyright (C) 2000, 2001, 2003 Free Software Foundation, Inc.
4 Contributed by Dan Pop <Dan.Pop@cern.ch>.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, write to the Free
18 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
21 /* Return: the address of the first occurence of chr in str or NULL
28 This implementation assumes little endian mode. For big endian mode,
29 the instruction czx1.r should be replaced by czx1.l.
31 The algorithm is fairly straightforward: search byte by byte until we
32 we get to a word aligned address, then search word by word as much as
33 possible; the remaining few bytes are searched one at a time.
35 The word by word search is performed by xor-ing the word with a word
36 containing chr in every byte. If there is a hit, the result will
37 contain a zero byte in the corresponding position. The presence and
38 position of that zero byte is detected with a czx instruction.
40 All the loops in this function could have had the internal branch removed
41 if br.ctop and br.cloop could be predicated :-(. */
60 alloc r2 = ar.pfs, 3, 0, 29, 32
62 .rotr value[MEMLAT+1], addr[MEMLAT+3], aux[2], poschr[2]
65 mov saved_lc = ar.lc // save the loop counter
67 mov saved_pr = pr // save the predicates
70 and tmp = 7, str // tmp = str % 8
71 cmp.ne p7, p0 = r0, r0 // clear p7
72 extr.u chr = in1, 0, 8 // chr = (unsigned char) in1
74 cmp.gtu p6, p0 = 16, in2 // use a simple loop for short
75 (p6) br.cond.spnt .srchfew ;; // searches
76 sub loopcnt = 8, tmp // loopcnt = 8 - tmp
77 cmp.eq p6, p0 = tmp, r0
78 (p6) br.cond.sptk .str_aligned;;
79 sub len = len, loopcnt
80 adds loopcnt = -1, loopcnt;;
85 cmp.eq p6, p0 = val, chr
86 (p6) br.cond.spnt .foundit
89 cmp.ne p6, p0 = r0, r0 // clear p6
90 shr.u loopcnt = len, 3 // loopcnt = len / 8
91 and len = 7, len ;; // remaining len = len & 7
92 adds loopcnt = -1, loopcnt
93 mov ar.ec = MEMLAT + 3
94 mux1 chrx8 = chr, @brcst ;; // get a word full of chr
96 mov pr.rot = 1 << 16 ;;
98 (p[0]) mov addr[0] = ret0
99 (p[0]) ld8.s value[0] = [ret0], 8 // speculative load
100 (p[MEMLAT]) chk.s value[MEMLAT], .recovery // check and recovery
101 (p[MEMLAT]) xor aux[0] = value[MEMLAT], chrx8
102 (p[MEMLAT+1]) czx1.r poschr[0] = aux[1]
103 (p[MEMLAT+2]) cmp.ne p7, p0 = 8, poschr[1]
104 (p7) br.cond.dpnt .foundit
107 adds loopcnt = -1, len
108 cmp.eq p6, p0 = len, r0
109 (p6) br.cond.spnt .notfound ;;
114 cmp.eq p6, p0 = val, chr
115 (p6) br.cond.dpnt .foundit
118 cmp.ne p6, p0 = r0, r0 // clear p6 (p7 was already 0 when we got here)
119 mov ret0 = r0 ;; // return NULL
121 .pred.rel "mutex" p6, p7
122 (p6) adds ret0 = -1, ret0 // if we got here from l1 or l3
123 (p7) add ret0 = addr[MEMLAT+2], poschr[1] // if we got here from l2
124 mov pr = saved_pr, -1
130 # error "MEMLAT must be 6!"
132 (p[MEMLAT-6]) add ret0 = -8, ret0;;
133 (p[MEMLAT-5]) add ret0 = -8, ret0;;
134 (p[MEMLAT-4]) add ret0 = -8, ret0;;
135 (p[MEMLAT-3]) add ret0 = -8, ret0;;
136 (p[MEMLAT-2]) add ret0 = -8, ret0;;
137 (p[MEMLAT-1]) add ret0 = -8, ret0;;
138 (p[MEMLAT]) add ret0 = -8, ret0;;
139 (p[MEMLAT+1]) add ret0 = -8, ret0;;
140 (p[MEMLAT+2]) add ret0 = -8, ret0;;
142 mov addr[MEMLAT+2] = ret0
143 ld8 tmp = [ret0];; // load the first unchecked 8byte
144 xor aux[1] = tmp, chrx8;;
145 czx1.r poschr[1] = aux[1];;
146 cmp.ne p7, p0 = 8, poschr[1]
147 (p7) br.cond.spnt .foundit;;
148 adds ret0 = 8, ret0 // load the next unchecked 8byte
153 weak_alias (__memchr, memchr)
154 #if !__BOUNDED_POINTERS__
155 weak_alias (__memchr, __ubp_memchr)
157 libc_hidden_builtin_def (memchr)