1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22 /* 23 * Copyright 2008 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 .file "memcmp.s" 28 29 /* 30 * memcmp(s1, s2, len) 31 * 32 * Compare n bytes: s1>s2: >0 s1==s2: 0 s1<s2: <0 33 * 34 * Fast assembler language version of the following C-program for memcmp 35 * which represents the `standard' for the C-library. 36 * 37 * int 38 * memcmp(const void *s1, const void *s2, size_t n) 39 * { 40 * if (s1 != s2 && n != 0) { 41 * const char *ps1 = s1; 42 * const char *ps2 = s2; 43 * do { 44 * if (*ps1++ != *ps2++) 45 * return (ps1[-1] - ps2[-1]); 46 * } while (--n != 0); 47 * } 48 * return (0); 49 * } 50 */ 51 52 #include <sys/asm_linkage.h> 53 54 ANSI_PRAGMA_WEAK(memcmp,function) 55 56 ENTRY(memcmp) 57 cmp %o0, %o1 ! s1 == s2? 58 be,pn %xcc, .cmpeq 59 cmp %o2, 17 60 bleu,a,pn %xcc, .cmpbyt ! for small counts go do bytes 61 sub %o1, %o0, %o1 62 63 andcc %o0, 3, %o3 ! is s1 aligned? 64 bz,a,pn %icc, .iss2 ! if so go check s2 65 andcc %o1, 3, %o4 ! is s2 aligned? 66 cmp %o3, 2 67 be,pn %icc, .algn2 68 cmp %o3, 3 69 70 .algn1: ldub [%o0], %o4 ! cmp one byte 71 inc %o0 72 ldub [%o1], %o5 73 inc %o1 74 dec %o2 75 be,pn %icc, .algn3 76 cmp %o4, %o5 77 be,pt %icc, .algn2 78 nop 79 b,a .noteq 80 81 .algn2: lduh [%o0], %o4 82 inc 2, %o0 83 ldub [%o1], %o5 84 inc 1, %o1 85 srl %o4, 8, %o3 86 cmp %o3, %o5 87 be,a,pt %icc, 1f 88 ldub [%o1], %o5 ! delay slot, get next byte from s2 89 b .noteq 90 mov %o3, %o4 ! delay slot, move *s1 to %o4 91 1: inc %o1 92 dec 2, %o2 93 and %o4, 0xff, %o4 94 cmp %o4, %o5 95 .algn3: be,a,pt %icc, .iss2 96 andcc %o1, 3, %o4 ! delay slot, is s2 aligned? 97 b,a .noteq 98 99 .cmpbyt:b .bytcmp 100 deccc %o2 101 1: ldub [%o0 + %o1], %o5 ! byte compare loop 102 inc %o0 103 cmp %o4, %o5 104 be,a,pt %icc, .bytcmp 105 deccc %o2 ! delay slot, compare count (len) 106 b,a .noteq 107 .bytcmp:bgeu,a,pt %xcc, 1b 108 ldub [%o0], %o4 109 .cmpeq: 110 retl ! strings compare equal 111 clr %o0 112 113 .noteq_word: ! words aren't equal. find unequal byte 114 srl %o4, 24, %o1 ! first byte 115 srl %o5, 24, %o2 116 cmp %o1, %o2 117 bne,pn %icc, 1f 118 sll %o4, 8, %o4 119 sll %o5, 8, %o5 120 srl %o4, 24, %o1 121 srl %o5, 24, %o2 122 cmp %o1, %o2 123 bne,pn %icc, 1f 124 sll %o4, 8, %o4 125 sll %o5, 8, %o5 126 srl %o4, 24, %o1 127 srl %o5, 24, %o2 128 cmp %o1, %o2 129 bne,pn %icc, 1f 130 sll %o4, 8, %o4 131 sll %o5, 8, %o5 132 srl %o4, 24, %o1 133 srl %o5, 24, %o2 134 1: 135 retl 136 sub %o1, %o2, %o0 ! delay slot 137 138 .noteq: 139 retl ! strings aren't equal 140 sub %o4, %o5, %o0 ! delay slot, return(*s1 - *s2) 141 142 .iss2: andn %o2, 3, %o3 ! count of aligned bytes 143 and %o2, 3, %o2 ! remaining bytes 144 bz,pn %icc, .w4cmp ! if s2 word aligned, compare words 145 cmp %o4, 2 146 be,pn %icc, .w2cmp ! s2 half aligned 147 cmp %o4, 1 148 149 .w3cmp: 150 dec 4, %o3 ! avoid reading beyond the last byte 151 inc 4, %o2 152 ldub [%o1], %g1 ! read a byte to align for word reads 153 inc 1, %o1 154 be,pt %icc, .w1cmp ! aligned to 1 or 3 bytes 155 sll %g1, 24, %o5 156 157 sub %o1, %o0, %o1 158 2: lduw [%o0 + %o1], %g1 159 lduw [%o0], %o4 160 inc 4, %o0 161 srl %g1, 8, %g5 ! merge with the other half 162 or %g5, %o5, %o5 163 cmp %o4, %o5 164 bne,pt %icc, .noteq_word 165 deccc 4, %o3 166 bnz,pt %xcc, 2b 167 sll %g1, 24, %o5 168 sub %o1, 1, %o1 ! used 3 bytes of the last word read 169 b .bytcmp 170 deccc %o2 171 172 .w1cmp: 173 dec 4, %o3 ! avoid reading beyond the last byte 174 inc 4, %o2 175 lduh [%o1], %g1 ! read 3 bytes to word align 176 inc 2, %o1 177 sll %g1, 8, %g5 178 or %o5, %g5, %o5 179 180 sub %o1, %o0, %o1 181 3: lduw [%o0 + %o1], %g1 182 lduw [%o0], %o4 183 inc 4, %o0 184 srl %g1, 24, %g5 ! merge with the other half 185 or %g5, %o5, %o5 186 cmp %o4, %o5 187 bne,pt %icc, .noteq_word 188 deccc 4, %o3 189 bnz,pt %xcc, 3b 190 sll %g1, 8, %o5 191 sub %o1, 3, %o1 ! used 1 byte of the last word read 192 b .bytcmp 193 deccc %o2 194 195 .w2cmp: 196 dec 4, %o3 ! avoid reading beyond the last byte 197 inc 4, %o2 198 lduh [%o1], %g1 ! read a halfword to align s2 199 inc 2, %o1 200 sll %g1, 16, %o5 201 sub %o1, %o0, %o1 202 4: lduw [%o0 + %o1], %g1 ! read a word from s2 203 lduw [%o0], %o4 ! read a word from s1 204 inc 4, %o0 205 srl %g1, 16, %g5 ! merge with the other half 206 or %g5, %o5, %o5 207 cmp %o4, %o5 208 bne,pn %icc, .noteq_word 209 deccc 4, %o3 210 bnz,pt %xcc, 4b 211 sll %g1, 16, %o5 212 sub %o1, 2, %o1 ! only used half of the last read word 213 b .bytcmp 214 deccc %o2 215 216 .w4cmp: 217 sub %o1, %o0, %o1 218 lduw [%o0 + %o1], %o5 219 5: lduw [%o0], %o4 220 inc 4, %o0 221 cmp %o4, %o5 222 bne,pt %icc, .noteq_word 223 deccc 4, %o3 224 bnz,a,pt %xcc, 5b 225 lduw [%o0 + %o1], %o5 226 b .bytcmp ! compare remaining bytes, if any 227 deccc %o2 228 229 SET_SIZE(memcmp) 230
Indexes created Fri Nov 27 08:09:20 UTC 2009
Terms of Use |
Privacy |
Trademarks |
Copyright Policy |
Site Guidelines |
Help
Your use of this web site or any of its content or software indicates your agreement to be bound by these Terms of Use.
Copyright © 1995-2008 Sun Microsystems, Inc.