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 "strncmp.s" 28 29/* 30 * strncmp(s1, s2, n) 31 * 32 * Compare strings (at most n bytes): s1>s2: >0 s1==s2: 0 s1<s2: <0 33 * 34 * Fast assembler language version of the following C-program for strncmp 35 * which represents the `standard' for the C-library. 36 * 37 * int 38 * strncmp(const char *s1, const char *s2, size_t n) 39 * { 40 * n++; 41 * if (s1 == s2) 42 * return (0); 43 * while (--n != 0 && *s1 == *s2++) 44 * if (*s1++ == '\0') 45 * return (0); 46 * return ((n == 0) ? 0 : (*s1 - s2[-1])); 47 * } 48 */ 49 50#include <sys/asm_linkage.h> 51 52 ENTRY(strncmp) 53 save %sp, -SA(WINDOWSIZE), %sp 54 cmp %i2, 8 55 blu,a .cmp_bytes ! for small counts go do bytes 56 sub %i0, %i1, %i0 ! delay slot, get diff from s1 - s2 57 andcc %i0, 3, %g0 ! is s1 aligned 581: bz .iss2 ! if so go check s2 59 andcc %i1, 3, %i3 ! is s2 aligned 60 61 deccc %i2 ! --n >= 0 ? 62 bcs .doneq 63 nop ! delay slot 64 65 ldub [%i0], %i4 ! else cmp one byte 66 ldub [%i1], %i5 67 inc %i0 68 cmp %i4, %i5 69 bne .noteqb 70 inc %i1 71 tst %i4 ! terminating zero 72 bnz 1b 73 andcc %i0, 3, %g0 74 b,a .doneq 75 76.iss2: 77 set 0x7efefeff, %l6 78 set 0x81010100, %l7 79 sethi %hi(0xff000000), %l0 ! masks to test for terminating null 80 sethi %hi(0x00ff0000), %l1 81 srl %l1, 8, %l2 ! generate 0x0000ff00 mask 82 83 bz .w4cmp ! if s2 word aligned, compare words 84 cmp %i3, 2 ! check if s2 half aligned 85 be .w2cmp 86 cmp %i3, 1 ! check if aligned to 1 or 3 bytes 87.w3cmp: ldub [%i1], %i5 88 inc 1, %i1 89 be .w1cmp 90 sll %i5, 24, %i5 91 sub %i0, %i1, %i0 922: 93 deccc 4, %i2 ! n >= 4 ? 94 bgeu,a 3f 95 ld [%i1], %i3 ! delay slot 96 dec %i1 ! reset s2 97 inc %i0 ! reset s1 diff 98 b .cmp_bytes ! do a byte at a time if n < 4 99 inc 4, %i2 1003: 101 ld [%i0 + %i1], %i4 102 inc 4, %i1 103 srl %i3, 8, %l4 ! merge with the other half 104 or %l4, %i5, %i5 105 cmp %i4, %i5 106 be 1f 107 108 add %i4, %l6, %l3 109 b,a .noteq 1101: xor %l3, %i4, %l3 111 and %l3, %l7, %l3 112 cmp %l3, %l7 113 be,a 2b 114 sll %i3, 24, %i5 115 116 ! 117 ! For 7-bit characters, we know one of the bytes is zero, but for 118 ! 8-bit characters, the zero detection algorithm gives some false 119 ! triggers ... check every byte individually. 120 ! 121 andcc %i4, %l0, %g0 ! check if first byte was zero 122 bnz 1f 123 andcc %i4, %l1, %g0 ! check if second byte was zero 124 b,a .doneq 1251: bnz 1f 126 andcc %i4, %l2, %g0 ! check if third byte was zero 127 b,a .doneq 1281: bnz 1f 129 andcc %i4, 0xff, %g0 ! check if last byte is zero 130 b,a .doneq 1311: bnz 2b 132 sll %i3, 24, %i5 133 b,a .doneq 134 135.w1cmp: clr %l4 136 lduh [%i1], %l4 137 inc 2, %i1 138 sll %l4, 8, %l4 139 or %i5, %l4, %i5 140 141 sub %i0, %i1, %i0 1423: 143 deccc 4, %i2 ! n >= 4 ? 144 bgeu,a 4f 145 ld [%i1], %i3 ! delay slot 146 dec 3, %i1 ! reset s2 147 inc 3, %i0 ! reset s1 diff 148 b .cmp_bytes ! do a byte at a time if n < 4 149 inc 4, %i2 1504: 151 ld [%i0 + %i1], %i4 152 inc 4, %i1 153 srl %i3, 24, %l4 ! merge with the other half 154 or %l4, %i5, %i5 155 cmp %i4, %i5 156 be 1f 157 158 add %i4, %l6, %l3 159 b,a .noteq 1601: xor %l3, %i4, %l3 161 and %l3, %l7, %l3 162 cmp %l3, %l7 163 be,a 3b 164 sll %i3, 8, %i5 165 166 andcc %i4, %l0, %g0 ! check if first byte was zero 167 bnz 1f 168 andcc %i4, %l1, %g0 ! check if second byte was zero 169 b,a .doneq 1701: bnz 1f 171 andcc %i4, %l2, %g0 ! check if third byte was zero 172 b,a .doneq 1731: bnz 1f 174 andcc %i4, 0xff, %g0 ! check if last byte is zero 175 b,a .doneq 1761: bnz 3b 177 sll %i3, 8, %i5 178 b,a .doneq 179 180.w2cmp: 181 lduh [%i1], %i5 ! read a halfword to align s2 182 inc 2, %i1 183 sll %i5, 16, %i5 184 185 sub %i0, %i1, %i0 1864: 187 deccc 4, %i2 ! n >= 4 ? 188 bgeu,a 5f 189 ld [%i1], %i3 ! delay slot 190 dec 2, %i1 ! reset s2 191 inc 2, %i0 ! reset s1 diff 192 b .cmp_bytes ! do a byte at a time if n < 4 193 inc 4, %i2 ! delay slot 1945: 195 ld [%i1 + %i0], %i4 ! read a word from s2 196 inc 4, %i1 197 srl %i3, 16, %l4 ! merge with the other half 198 or %l4, %i5, %i5 199 cmp %i4, %i5 200 be 1f 201 202 add %i4, %l6, %l3 203 b,a .noteq 2041: xor %l3, %i4, %l3 ! are any bytes 0? 205 and %l3, %l7, %l3 206 cmp %l3, %l7 207 be,a 4b 208 sll %i3, 16, %i5 209 210 andcc %i4, %l0, %g0 ! check if first byte was zero 211 bnz 1f 212 andcc %i4, %l1, %g0 ! check if second byte was zero 213 b,a .doneq 2141: bnz 1f 215 andcc %i4, %l2, %g0 ! check if third byte was zero 216 b,a .doneq 2171: bnz 1f 218 andcc %i4, 0xff, %g0 ! check if last byte is zero 219 b,a .doneq 2201: bnz 4b 221 sll %i3, 16, %i5 222 b,a .doneq 223 224.w4cmp: sub %i0, %i1, %i0 225 ld [%i1], %i5 ! read a word from s1 2265: cmp %i2,0 227 be,a .doneq 228 nop 229 ld [%i1], %i5 ! read a word from s1 230 deccc 4, %i2 ! n >= 4 ? 231 bcs,a .cmp_bytes ! do a byte at a time if n < 4 232 inc 4, %i2 233 234 ld [%i1 + %i0], %i4 ! read a word from s2 235 cmp %i4, %i5 236 inc 4, %i1 237 be 1f 238 239 add %i4, %l6, %l3 240 b,a .noteq 2411: xor %l3, %i4, %l3 242 and %l3, %l7, %l3 243 cmp %l3, %l7 244 be,a 5b 245 nop 246 247 andcc %i4, %l0, %g0 ! check if first byte was zero 248 bnz 1f 249 andcc %i4, %l1, %g0 ! check if second byte was zero 250 b,a .doneq 2511: bnz 1f 252 andcc %i4, %l2, %g0 ! check if third byte was zero 253 b,a .doneq 2541: bnz 1f 255 andcc %i4, 0xff, %g0 ! check if last byte is zero 256 b,a .doneq 2571: bnz,a 5b 258 ld [%i1], %i5 259.doneq: ret 260 restore %g0, %g0, %o0 ! equal return zero 261 262.noteq: srl %i4, 24, %l4 263 srl %i5, 24, %l5 264 subcc %l4, %l5, %i0 265 bne 6f 266 andcc %l4, 0xff, %g0 267 bz .doneq 268 sll %i4, 8, %l4 269 sll %i5, 8, %l5 270 srl %l4, 24, %l4 271 srl %l5, 24, %l5 272 subcc %l4, %l5, %i0 273 bne 6f 274 andcc %l4, 0xff, %g0 275 bz .doneq 276 sll %i4, 16, %l4 277 sll %i5, 16, %l5 278 srl %l4, 24, %l4 279 srl %l5, 24, %l5 280 subcc %l4, %l5, %i0 281 bne 6f 282 andcc %l4, 0xff, %g0 283 bz .doneq 284 nop 285.noteqb: 286 and %i4, 0xff, %l4 287 and %i5, 0xff, %l5 288 subcc %l4, %l5, %i0 2896: ret 290 restore %i0, %g0, %o0 291 292 ! Do a byte by byte comparison, disregarding alignments 293.cmp_bytes: 294 deccc %i2 ! --n >= 0 ? 2951: 296 bcs .doneq 297 nop ! delay slot 298 ldub [%i1 + %i0], %i4 ! read a word from s1 299 ldub [%i1], %i5 ! read a word from s2 300 301 inc %i1 302 cmp %i4, %i5 303 bne .noteqb 304 tst %i4 ! terminating zero 305 bnz 1b 306 deccc %i2 ! --n >= 0 307 b,a .doneq 308 309 SET_SIZE(strncmp) 310