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 (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved. 24 */ 25 26/* 27 * The ascii_strcasecmp() function is a case insensitive versions of strcmp(). 28 * It assumes the ASCII character set and ignores differences in case 29 * when comparing lower and upper case characters. In other words, it 30 * behaves as if both strings had been converted to lower case using 31 * tolower() in the "C" locale on each byte, and the results had then 32 * been compared using strcmp(). 33 * 34 * The assembly code below is an optimized version of the following C 35 * reference: 36 * 37 * static const char charmap[] = { 38 * '\000', '\001', '\002', '\003', '\004', '\005', '\006', '\007', 39 * '\010', '\011', '\012', '\013', '\014', '\015', '\016', '\017', 40 * '\020', '\021', '\022', '\023', '\024', '\025', '\026', '\027', 41 * '\030', '\031', '\032', '\033', '\034', '\035', '\036', '\037', 42 * '\040', '\041', '\042', '\043', '\044', '\045', '\046', '\047', 43 * '\050', '\051', '\052', '\053', '\054', '\055', '\056', '\057', 44 * '\060', '\061', '\062', '\063', '\064', '\065', '\066', '\067', 45 * '\070', '\071', '\072', '\073', '\074', '\075', '\076', '\077', 46 * '\100', '\141', '\142', '\143', '\144', '\145', '\146', '\147', 47 * '\150', '\151', '\152', '\153', '\154', '\155', '\156', '\157', 48 * '\160', '\161', '\162', '\163', '\164', '\165', '\166', '\167', 49 * '\170', '\171', '\172', '\133', '\134', '\135', '\136', '\137', 50 * '\140', '\141', '\142', '\143', '\144', '\145', '\146', '\147', 51 * '\150', '\151', '\152', '\153', '\154', '\155', '\156', '\157', 52 * '\160', '\161', '\162', '\163', '\164', '\165', '\166', '\167', 53 * '\170', '\171', '\172', '\173', '\174', '\175', '\176', '\177', 54 * '\200', '\201', '\202', '\203', '\204', '\205', '\206', '\207', 55 * '\210', '\211', '\212', '\213', '\214', '\215', '\216', '\217', 56 * '\220', '\221', '\222', '\223', '\224', '\225', '\226', '\227', 57 * '\230', '\231', '\232', '\233', '\234', '\235', '\236', '\237', 58 * '\240', '\241', '\242', '\243', '\244', '\245', '\246', '\247', 59 * '\250', '\251', '\252', '\253', '\254', '\255', '\256', '\257', 60 * '\260', '\261', '\262', '\263', '\264', '\265', '\266', '\267', 61 * '\270', '\271', '\272', '\273', '\274', '\275', '\276', '\277', 62 * '\300', '\301', '\302', '\303', '\304', '\305', '\306', '\307', 63 * '\310', '\311', '\312', '\313', '\314', '\315', '\316', '\317', 64 * '\320', '\321', '\322', '\323', '\324', '\325', '\326', '\327', 65 * '\330', '\331', '\332', '\333', '\334', '\335', '\336', '\337', 66 * '\340', '\341', '\342', '\343', '\344', '\345', '\346', '\347', 67 * '\350', '\351', '\352', '\353', '\354', '\355', '\356', '\357', 68 * '\360', '\361', '\362', '\363', '\364', '\365', '\366', '\367', 69 * '\370', '\371', '\372', '\373', '\374', '\375', '\376', '\377', 70 * }; 71 * 72 * int 73 * ascii_strcasecmp(const char *s1, const char *s2) 74 * { 75 * const unsigned char *cm = (const unsigned char *)charmap; 76 * const unsigned char *us1 = (const unsigned char *)s1; 77 * const unsigned char *us2 = (const unsigned char *)s2; 78 * 79 * while (cm[*us1] == cm[*us2++]) 80 * if (*us1++ == '\0') 81 * return (0); 82 * return (cm[*us1] - cm[*(us2 - 1)]); 83 * } 84 * 85 * The following algorithm, from a 1987 news posting by Alan Mycroft, is 86 * used for finding null bytes in a word: 87 * 88 * #define has_null(word) ((word - 0x01010101) & (~word & 0x80808080)) 89 * 90 * The following algorithm is used for a wordwise tolower() operation: 91 * 92 * unsigned int 93 * parallel_tolower (unsigned int x) 94 * { 95 * unsigned int p; 96 * unsigned int q; 97 * 98 * unsigned int m1 = 0x80808080; 99 * unsigned int m2 = 0x3f3f3f3f; 100 * unsigned int m3 = 0x25252525; 101 * 102 * q = x & ~m1;// newb = byte & 0x7F 103 * p = q + m2; // newb > 0x5A --> MSB set 104 * q = q + m3; // newb < 0x41 --> MSB clear 105 * p = p & ~q; // newb > 0x40 && newb < 0x5B --> MSB set 106 * q = m1 & ~x;// byte < 0x80 --> 0x80 107 * q = p & q; // newb > 0x40 && newb < 0x5B && byte < 0x80 -> 0x80,else 0 108 * q = q >> 2; // newb > 0x40 && newb < 0x5B && byte < 0x80 -> 0x20,else 0 109 * return (x + q); // translate uppercase characters to lowercase 110 * } 111 * 112 * Both algorithms have been tested exhaustively for all possible 2^32 inputs. 113 */ 114 115#include <sys/asm_linkage.h> 116 117 ! The first part of this algorithm walks through the beginning of 118 ! both strings a byte at a time until the source ptr is aligned to 119 ! a word boundary. During these steps, the bytes are translated to 120 ! lower-case if they are upper-case, and are checked against 121 ! the source string. 122 123 ENTRY(ascii_strcasecmp) 124 125 .align 32 126 127 save %sp, -SA(WINDOWSIZE), %sp 128 subcc %i0, %i1, %i2 ! s1 == s2 ? 129 bz .stringsequal ! yup, done, strings equal 130 andcc %i0, 3, %i3 ! s1 word-aligned ? 131 bz .s1aligned1 ! yup 132 sethi %hi(0x80808080), %i4 ! start loading Mycroft's magic1 133 134 ldub [%i1 + %i2], %i0 ! s1[0] 135 ldub [%i1], %g1 ! s2[0] 136 sub %i0, 'A', %l0 ! transform for faster uppercase check 137 sub %g1, 'A', %l1 ! transform for faster uppercase check 138 cmp %l0, ('Z' - 'A') ! s1[0] uppercase? 139 bleu,a .noxlate11 ! yes 140 add %i0, ('a' - 'A'), %i0 ! s1[0] = tolower(s1[0]) 141.noxlate11: 142 cmp %l1, ('Z' - 'A') ! s2[0] uppercase? 143 bleu,a .noxlate12 ! yes 144 add %g1, ('a' - 'A'), %g1 ! s2[0] = tolower(s2[0]) 145.noxlate12: 146 subcc %i0, %g1, %i0 ! tolower(s1[0]) != tolower(s2[0]) ? 147 bne .done ! yup, done 148 inc %i1 ! s1++, s2++ 149 addcc %i0, %g1, %i0 ! s1[0] == 0 ? 150 bz .done ! yup, done, strings equal 151 cmp %i3, 3 ! s1 aligned now? 152 bz .s1aligned2 ! yup 153 sethi %hi(0x01010101), %i5 ! start loading Mycroft's magic2 154 155 ldub [%i1 + %i2], %i0 ! s1[1] 156 ldub [%i1], %g1 ! s2[1] 157 sub %i0, 'A', %l0 ! transform for faster uppercase check 158 sub %g1, 'A', %l1 ! transform for faster uppercase check 159 cmp %l0, ('Z' - 'A') ! s1[1] uppercase? 160 bleu,a .noxlate21 ! yes 161 add %i0, ('a' - 'A'), %i0 ! s1[1] = tolower(s1[1]) 162.noxlate21: 163 cmp %l1, ('Z' - 'A') ! s2[1] uppercase? 164 bleu,a .noxlate22 ! yes 165 add %g1, ('a' - 'A'), %g1 ! s2[1] = tolower(s2[1]) 166.noxlate22: 167 subcc %i0, %g1, %i0 ! tolower(s1[1]) != tolower(s2[1]) ? 168 bne .done ! yup, done 169 inc %i1 ! s1++, s2++ 170 addcc %i0, %g1, %i0 ! s1[1] == 0 ? 171 bz .done ! yup, done, strings equal 172 cmp %i3, 2 ! s1 aligned now? 173 bz .s1aligned3 ! yup 174 or %i4, %lo(0x80808080),%i4! finish loading Mycroft's magic1 175 176 ldub [%i1 + %i2], %i0 ! s1[2] 177 ldub [%i1], %g1 ! s2[2] 178 sub %i0, 'A', %l0 ! transform for faster uppercase check 179 sub %g1, 'A', %l1 ! transform for faster uppercase check 180 cmp %l0, ('Z' - 'A') ! s1[2] uppercase? 181 bleu,a .noxlate31 ! yes 182 add %i0, ('a' - 'A'), %i0 ! s1[2] = tolower(s1[2]) 183.noxlate31: 184 cmp %l1, ('Z' - 'A') ! s2[2] uppercase? 185 bleu,a .noxlate32 ! yes 186 add %g1, ('a' - 'A'), %g1 ! s2[2] = tolower(s2[2]) 187.noxlate32: 188 subcc %i0, %g1, %i0 ! tolower(s1[2]) != tolower(s2[2]) ? 189 bne .done ! yup, done 190 inc %i1 ! s1++, s2++ 191 addcc %i0, %g1, %i0 ! s1[2] == 0 ? 192 bz .done ! yup, done, strings equal 193 or %i5, %lo(0x01010101),%i5! finish loading Mycroft's magic2 194 ba .s1aligned4 ! s1 aligned now 195 andcc %i1, 3, %i3 ! s2 word-aligned ? 196 197 ! Here, we initialize our checks for a zero byte and decide 198 ! whether or not we can optimize further if we're fortunate 199 ! enough to have a word aligned desintation 200 201.s1aligned1: 202 sethi %hi(0x01010101), %i5 ! start loading Mycroft's magic2 203.s1aligned2: 204 or %i4, %lo(0x80808080),%i4! finish loading Mycroft's magic1 205.s1aligned3: 206 or %i5, %lo(0x01010101),%i5! finish loading Mycroft's magic2 207 andcc %i1, 3, %i3 ! s2 word aligned ? 208.s1aligned4: 209 sethi %hi(0x3f3f3f3f), %l2 ! load m2 for parallel tolower() 210 sethi %hi(0x25252525), %l3 ! load m3 for parallel tolower() 211 or %l2, %lo(0x3f3f3f3f),%l2! finish loading m2 212 bz .word4 ! yup, s2 word-aligned 213 or %l3, %lo(0x25252525),%l3! finish loading m3 214 215 add %i2, %i3, %i2 ! start adjusting offset s1-s2 216 sll %i3, 3, %l6 ! shift factor for left shifts 217 andn %i1, 3, %i1 ! round s1 pointer down to next word 218 sub %g0, %l6, %l7 ! shift factor for right shifts 219 orn %i3, %g0, %i3 ! generate all ones 220 lduw [%i1], %i0 ! new lower word from s2 221 srl %i3, %l6, %i3 ! mask for fixing up bytes 222 sll %i0, %l6, %g1 ! partial unaligned word from s2 223 orn %i0, %i3, %i0 ! force start bytes to non-zero 224 nop ! pad to align loop to 16-byte boundary 225 nop ! pad to align loop to 16-byte boundary 226 227 ! This is the comparision procedure used if the destination is not 228 ! word aligned, if it is, we use word4 & cmp4 229 230.cmp: 231 andn %i4, %i0, %l4 ! ~word & 0x80808080 232 sub %i0, %i5, %l5 ! word - 0x01010101 233 andcc %l5, %l4, %g0 ! (word - 0x01010101) & ~word & 0x80808080 234 bz,a .doload ! null byte in previous aligned s2 word 235 lduw [%i1 + 4], %i0 ! load next aligned word from s2 236.doload: 237 srl %i0, %l7, %i3 ! byte(s) from new aligned word from s2 238 or %g1, %i3, %g1 ! merge to get unaligned word from s2 239 lduw [%i1 + %i2], %i3 ! x1 = word from s1 240 andn %i3, %i4, %l0 ! q1 = x1 & ~m1 241 andn %g1, %i4, %l4 ! q2 = x2 & ~m1 242 add %l0, %l2, %l1 ! p1 = q1 + m2 243 add %l4, %l2, %l5 ! p2 = q2 + m2 244 add %l0, %l3, %l0 ! q1 = q1 + m3 245 add %l4, %l3, %l4 ! q2 = q2 + m3 246 andn %l1, %l0, %l1 ! p1 = p1 & ~q1 247 andn %l5, %l4, %l5 ! p2 = p2 & ~q2 248 andn %i4, %i3, %l0 ! q1 = m1 & ~x1 249 andn %i4, %g1, %l4 ! q2 = m1 & ~x2 250 and %l0, %l1, %l0 ! q1 = p1 & q1 251 and %l4, %l5, %l4 ! q2 = p2 & q2 252 srl %l0, 2, %l0 ! q1 = q1 >> 2 253 srl %l4, 2, %l4 ! q2 = q2 >> 2 254 add %l0, %i3, %i3 ! lowercase word from s1 255 add %l4, %g1, %g1 ! lowercase word from s2 256 cmp %i3, %g1 ! tolower(*s1) != tolower(*s2) ? 257 bne .wordsdiffer ! yup, now find byte that is different 258 add %i1, 4, %i1 ! s1+=4, s2+=4 259 andn %i4, %i3, %l4 ! ~word & 0x80808080 260 sub %i3, %i5, %l5 ! word - 0x01010101 261 andcc %l5, %l4, %g0 ! (word - 0x01010101) & ~word & 0x80808080 262 bz .cmp ! no null-byte in s1 yet 263 sll %i0, %l6, %g1 ! bytes from old aligned word from s2 264 265 ! words are equal but the end of s1 has been reached 266 ! this means the strings must be equal 267.stringsequal: 268 ret ! return 269 restore %g0, %g0, %o0 ! return 0, i.e. strings are equal 270 nop ! pad 271 272 ! we have a word aligned source and destination! This means 273 ! things get to go fast! 274 275.word4: 276 lduw [%i1 + %i2], %i3 ! x1 = word from s1 277 278.cmp4: 279 andn %i3, %i4, %l0 ! q1 = x1 & ~m1 280 lduw [%i1], %g1 ! x2 = word from s2 281 andn %g1, %i4, %l4 ! q2 = x2 & ~m1 282 add %l0, %l2, %l1 ! p1 = q1 + m2 283 add %l4, %l2, %l5 ! p2 = q2 + m2 284 add %l0, %l3, %l0 ! q1 = q1 + m3 285 add %l4, %l3, %l4 ! q2 = q2 + m3 286 andn %l1, %l0, %l1 ! p1 = p1 & ~q1 287 andn %l5, %l4, %l5 ! p2 = p2 & ~q2 288 andn %i4, %i3, %l0 ! q1 = m1 & ~x1 289 andn %i4, %g1, %l4 ! q2 = m1 & ~x2 290 and %l0, %l1, %l0 ! q1 = p1 & q1 291 and %l4, %l5, %l4 ! q2 = p2 & q2 292 srl %l0, 2, %l0 ! q1 = q1 >> 2 293 srl %l4, 2, %l4 ! q2 = q2 >> 2 294 add %l0, %i3, %i3 ! lowercase word from s1 295 add %l4, %g1, %g1 ! lowercase word from s2 296 cmp %i3, %g1 ! tolower(*s1) != tolower(*s2) ? 297 bne .wordsdiffer ! yup, now find mismatching character 298 add %i1, 4, %i1 ! s1+=4, s2+=4 299 andn %i4, %i3, %l4 ! ~word & 0x80808080 300 sub %i3, %i5, %l5 ! word - 0x01010101 301 andcc %l5, %l4, %g0 ! (word - 0x01010101) & ~word & 0x80808080 302 bz,a .cmp4 ! no null-byte in s1 yet 303 lduw [%i1 + %i2], %i3 ! load word from s1 304 305 ! words are equal but the end of s1 has been reached 306 ! this means the strings must be equal 307.stringsequal4: 308 ret ! return 309 restore %g0, %g0, %o0 ! return 0, i.e. strings are equal 310 311.wordsdiffer: 312 srl %g1, 24, %i2 ! first byte of mismatching word in s2 313 srl %i3, 24, %i1 ! first byte of mismatching word in s1 314 subcc %i1, %i2, %i0 ! *s1-*s2 315 bnz .done ! bytes differ, return difference 316 srl %g1, 16, %i2 ! second byte of mismatching word in s2 317 andcc %i1, 0xff, %i0 ! *s1 == 0 ? 318 bz .done ! yup, done, strings equal 319 320 ! we know byte 1 is equal, so can compare bytes 1,2 as a group 321 322 srl %i3, 16, %i1 ! second byte of mismatching word in s1 323 subcc %i1, %i2, %i0 ! *s1-*s2 324 bnz .done ! bytes differ, return difference 325 srl %g1, 8, %i2 ! third byte of mismatching word in s2 326 andcc %i1, 0xff, %i0 ! *s1 == 0 ? 327 bz .done ! yup, done, strings equal 328 329 ! we know bytes 1, 2 are equal, so can compare bytes 1,2,3 as a group 330 331 srl %i3, 8, %i1 ! third byte of mismatching word in s1 332 subcc %i1, %i2, %i0 ! *s1-*s2 333 bnz .done ! bytes differ, return difference 334 andcc %i1, 0xff, %g0 ! *s1 == 0 ? 335 bz .stringsequal ! yup, done, strings equal 336 337 ! we know bytes 1,2,3 are equal, so can compare bytes 1,2,3,4 as group 338 339 subcc %i3, %g1, %i0 ! *s1-*s2 340 bz,a .done ! bytes differ, return difference 341 andcc %i3, 0xff, %i0 ! *s1 == 0, strings equal 342 343.done: 344 ret ! return 345 restore %i0, %g0, %o0 ! return 0 or byte difference 346 347 SET_SIZE(ascii_strcasecmp) 348