1 /* Optimized version of the standard memcmp() function.
2 This file is part of the GNU C Library.
3 Copyright (C) 2000, 2001, 2004 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 result of the comparison
28 In this form, it assumes little endian mode. For big endian mode, the
29 the two shifts in .l2 must be inverted:
31 shl tmp1[0] = r[1 + MEMLAT], sh1 // tmp1 = w0 << sh1
32 shr.u tmp2[0] = r[0 + MEMLAT], sh2 // tmp2 = w1 >> sh2
34 and all the mux1 instructions should be replaced by plain mov's. */
59 alloc r2 = ar.pfs, 3, 37, 0, 40
61 .rotr r[MEMLAT + 2], q[MEMLAT + 5], tmp1[4], tmp2[4], val[2]
62 .rotp p[MEMLAT + 4 + 1]
64 mov ret0 = r0 /* by default return value = 0 */
66 mov saved_pr = pr /* save the predicate registers */
68 mov saved_lc = ar.lc /* save the loop counter */
70 mov dest = in0 /* dest */
71 mov src = in1 /* src */
72 mov len = in2 /* len */
73 sub tmp = r0, in0 /* tmp = -dest */
75 and loopcnt = 7, tmp /* loopcnt = -dest % 8 */
76 cmp.ge p6, p0 = OP_T_THRES, len /* is len <= OP_T_THRES */
77 (p6) br.cond.spnt .cmpfew /* compare byte by byte */
79 cmp.eq p6, p0 = loopcnt, r0
80 (p6) br.cond.sptk .dest_aligned
81 sub len = len, loopcnt /* len -= -dest % 8 */
82 adds loopcnt = -1, loopcnt /* --loopcnt */
85 .l1: /* copy -dest % 8 bytes */
86 ld1 value1 = [src], 1 /* value = *src++ */
87 ld1 value2 = [dest], 1
89 cmp.ne p6, p0 = value1, value2
90 (p6) br.cond.spnt .done
93 and sh1 = 7, src /* sh1 = src % 8 */
94 and tmp = -8, len /* tmp = len & -OPSIZ */
95 and asrc = -8, src /* asrc = src & -OPSIZ -- align src */
96 shr.u loopcnt = len, 3 /* loopcnt = len / 8 */
97 and len = 7, len ;; /* len = len % 8 */
98 shl sh1 = sh1, 3 /* sh1 = 8 * (src % 8) */
99 adds loopcnt = -1, loopcnt /* --loopcnt */
100 mov pr.rot = 1 << 16 ;; /* set rotating predicates */
101 sub sh2 = 64, sh1 /* sh2 = 64 - sh1 */
102 mov ar.lc = loopcnt /* set LC */
103 cmp.eq p6, p0 = sh1, r0 /* is the src aligned? */
104 (p6) br.cond.sptk .src_aligned
105 add src = src, tmp /* src += len & -OPSIZ */
106 mov ar.ec = MEMLAT + 4 + 1 /* four more passes needed */
107 ld8 r[1] = [asrc], 8 ;; /* r[1] = w0 */
110 /* We enter this loop with p6 cleared by the above comparison */
113 (p[0]) ld8 r[0] = [asrc], 8 /* r[0] = w1 */
114 (p[0]) ld8 q[0] = [dest], 8
115 (p[MEMLAT]) shr.u tmp1[0] = r[1 + MEMLAT], sh1 /* tmp1 = w0 >> sh1 */
116 (p[MEMLAT]) shl tmp2[0] = r[0 + MEMLAT], sh2 /* tmp2 = w1 << sh2 */
117 (p[MEMLAT+4]) cmp.ne p6, p0 = q[MEMLAT + 4], val[1]
118 (p[MEMLAT+3]) or val[0] = tmp1[3], tmp2[3] /* val = tmp1 | tmp2 */
119 (p6) br.cond.spnt .l2exit
123 mux1 value1 = r[MEMLAT], @rev
124 mux1 value2 = q[MEMLAT], @rev
125 cmp.ne p6, p0 = r0, r0 ;; /* clear p6 */
127 (p6) mux1 value1 = val[1], @rev
128 (p6) mux1 value2 = q[MEMLAT + 4], @rev ;;
129 cmp.ltu p6, p7 = value2, value1 ;;
132 mov pr = saved_pr, -1 /* restore the predicate registers */
133 mov ar.lc = saved_lc /* restore the loop counter */
136 cmp.ne p6, p0 = r0, r0 /* clear p6 */
137 mov ar.ec = MEMLAT + 1 ;; /* set EC */
139 (p[0]) ld8 r[0] = [src], 8
140 (p[0]) ld8 q[0] = [dest], 8
141 (p[MEMLAT]) cmp.ne p6, p0 = r[MEMLAT], q[MEMLAT]
142 (p6) br.cond.spnt .l3exit
145 cmp.eq p6, p0 = len, r0 /* is len == 0 ? */
146 adds len = -1, len /* --len; */
147 (p6) br.cond.spnt .restore_and_exit ;;
150 ld1 value1 = [src], 1
151 ld1 value2 = [dest], 1
153 cmp.ne p6, p0 = value1, value2
154 (p6) br.cond.spnt .done
157 (p6) sub ret0 = value2, value1 /* don't execute it if falling thru */
159 mov pr = saved_pr, -1 /* restore the predicate registers */
160 mov ar.lc = saved_lc /* restore the loop counter */
163 libc_hidden_def (memcmp)
164 #ifdef __UCLIBC_SUSV3_LEGACY__
165 strong_alias (memcmp, bcmp)