Mercurial > hg > octave-shane > gnulib-hg
annotate lib/memcmp.c @ 10375:f96e845fc36d
Avoid some "gcc -pedantic" warnings.
| author | Bruno Haible <bruno@clisp.org> |
|---|---|
| date | Sat, 30 Aug 2008 03:09:15 +0200 |
| parents | bbbbbf4cd1c5 |
| children | 1cc89f3c5e6b |
| rev | line source |
|---|---|
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* _fpending.c: Include <config.h> unconditionally, since we no
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1 /* Copyright (C) 1991, 1993, 1995, 1997, 1998, 2003, 2006 Free Software |
| 4664 | 2 Foundation, Inc. |
| 3 | |
| 387 | 4 Contributed by Torbjorn Granlund (tege@sics.se). |
| 5 | |
| 1112 | 6 NOTE: The canonical source of this file is maintained with the GNU C Library. |
| 7 Bugs can be reported to bug-glibc@prep.ai.mit.edu. | |
| 387 | 8 |
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Change copyright notice from GPLv2+ to GPLv3+.
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9 This program is free software: you can redistribute it and/or modify it |
| 1112 | 10 under the terms of the GNU General Public License as published by the |
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Change copyright notice from GPLv2+ to GPLv3+.
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11 Free Software Foundation; either version 3 of the License, or any |
| 1112 | 12 later version. |
| 387 | 13 |
| 1112 | 14 This program is distributed in the hope that it will be useful, |
| 15 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 17 GNU General Public License for more details. | |
| 387 | 18 |
| 1112 | 19 You should have received a copy of the GNU General Public License |
|
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20 along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 387 | 21 |
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* _fpending.c: Include <config.h> unconditionally, since we no
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22 #ifndef _LIBC |
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Use a consistent style for including <config.h>.
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23 # include <config.h> |
| 387 | 24 #endif |
| 25 | |
| 4664 | 26 #include <string.h> |
| 387 | 27 |
| 1112 | 28 #undef memcmp |
| 29 | |
| 387 | 30 #ifdef _LIBC |
| 31 | |
| 1112 | 32 # include <memcopy.h> |
| 2934 | 33 # include <endian.h> |
| 34 | |
| 35 # if __BYTE_ORDER == __BIG_ENDIAN | |
| 36 # define WORDS_BIGENDIAN | |
| 37 # endif | |
| 387 | 38 |
| 39 #else /* Not in the GNU C library. */ | |
| 40 | |
| 1112 | 41 # include <sys/types.h> |
| 387 | 42 |
| 43 /* Type to use for aligned memory operations. | |
| 44 This should normally be the biggest type supported by a single load | |
| 45 and store. Must be an unsigned type. */ | |
| 1112 | 46 # define op_t unsigned long int |
| 47 # define OPSIZ (sizeof(op_t)) | |
| 387 | 48 |
| 49 /* Threshold value for when to enter the unrolled loops. */ | |
| 1112 | 50 # define OP_T_THRES 16 |
| 387 | 51 |
| 52 /* Type to use for unaligned operations. */ | |
| 53 typedef unsigned char byte; | |
| 54 | |
| 1112 | 55 # ifndef WORDS_BIGENDIAN |
| 56 # define MERGE(w0, sh_1, w1, sh_2) (((w0) >> (sh_1)) | ((w1) << (sh_2))) | |
| 57 # else | |
| 58 # define MERGE(w0, sh_1, w1, sh_2) (((w0) << (sh_1)) | ((w1) >> (sh_2))) | |
| 59 # endif | |
| 387 | 60 |
| 61 #endif /* In the GNU C library. */ | |
| 62 | |
| 63 #ifdef WORDS_BIGENDIAN | |
| 1112 | 64 # define CMP_LT_OR_GT(a, b) ((a) > (b) ? 1 : -1) |
| 387 | 65 #else |
| 1112 | 66 # define CMP_LT_OR_GT(a, b) memcmp_bytes ((a), (b)) |
| 387 | 67 #endif |
| 68 | |
| 69 /* BE VERY CAREFUL IF YOU CHANGE THIS CODE! */ | |
| 70 | |
| 71 /* The strategy of this memcmp is: | |
| 72 | |
| 73 1. Compare bytes until one of the block pointers is aligned. | |
| 74 | |
| 75 2. Compare using memcmp_common_alignment or | |
| 76 memcmp_not_common_alignment, regarding the alignment of the other | |
| 77 block after the initial byte operations. The maximum number of | |
| 78 full words (of type op_t) are compared in this way. | |
| 79 | |
| 80 3. Compare the few remaining bytes. */ | |
| 81 | |
| 82 #ifndef WORDS_BIGENDIAN | |
| 83 /* memcmp_bytes -- Compare A and B bytewise in the byte order of the machine. | |
| 84 A and B are known to be different. | |
| 85 This is needed only on little-endian machines. */ | |
| 1112 | 86 |
| 87 # ifdef __GNUC__ | |
| 387 | 88 __inline |
| 1112 | 89 # endif |
| 387 | 90 static int |
| 1557 | 91 memcmp_bytes (long unsigned int a, long unsigned int b) |
| 387 | 92 { |
| 93 long int srcp1 = (long int) &a; | |
| 94 long int srcp2 = (long int) &b; | |
| 95 op_t a0, b0; | |
| 96 | |
| 97 do | |
| 98 { | |
| 99 a0 = ((byte *) srcp1)[0]; | |
| 100 b0 = ((byte *) srcp2)[0]; | |
| 101 srcp1 += 1; | |
| 102 srcp2 += 1; | |
| 103 } | |
| 104 while (a0 == b0); | |
| 105 return a0 - b0; | |
| 106 } | |
| 107 #endif | |
| 108 | |
| 109 /* memcmp_common_alignment -- Compare blocks at SRCP1 and SRCP2 with LEN `op_t' | |
| 110 objects (not LEN bytes!). Both SRCP1 and SRCP2 should be aligned for | |
| 111 memory operations on `op_t's. */ | |
| 112 #ifdef __GNUC__ | |
| 113 __inline | |
| 114 #endif | |
| 115 static int | |
| 1557 | 116 memcmp_common_alignment (long int srcp1, long int srcp2, size_t len) |
| 387 | 117 { |
| 118 op_t a0, a1; | |
| 119 op_t b0, b1; | |
| 120 | |
| 121 switch (len % 4) | |
| 122 { | |
| 1112 | 123 default: /* Avoid warning about uninitialized local variables. */ |
| 387 | 124 case 2: |
| 125 a0 = ((op_t *) srcp1)[0]; | |
| 126 b0 = ((op_t *) srcp2)[0]; | |
| 127 srcp1 -= 2 * OPSIZ; | |
| 128 srcp2 -= 2 * OPSIZ; | |
| 129 len += 2; | |
| 130 goto do1; | |
| 131 case 3: | |
| 132 a1 = ((op_t *) srcp1)[0]; | |
| 133 b1 = ((op_t *) srcp2)[0]; | |
| 134 srcp1 -= OPSIZ; | |
| 135 srcp2 -= OPSIZ; | |
| 136 len += 1; | |
| 137 goto do2; | |
| 138 case 0: | |
| 139 if (OP_T_THRES <= 3 * OPSIZ && len == 0) | |
| 140 return 0; | |
| 141 a0 = ((op_t *) srcp1)[0]; | |
| 142 b0 = ((op_t *) srcp2)[0]; | |
| 143 goto do3; | |
| 144 case 1: | |
| 145 a1 = ((op_t *) srcp1)[0]; | |
| 146 b1 = ((op_t *) srcp2)[0]; | |
| 147 srcp1 += OPSIZ; | |
| 148 srcp2 += OPSIZ; | |
| 149 len -= 1; | |
| 150 if (OP_T_THRES <= 3 * OPSIZ && len == 0) | |
| 151 goto do0; | |
| 152 /* Fall through. */ | |
| 153 } | |
| 154 | |
| 155 do | |
| 156 { | |
| 157 a0 = ((op_t *) srcp1)[0]; | |
| 158 b0 = ((op_t *) srcp2)[0]; | |
| 159 if (a1 != b1) | |
| 160 return CMP_LT_OR_GT (a1, b1); | |
| 161 | |
| 162 do3: | |
| 163 a1 = ((op_t *) srcp1)[1]; | |
| 164 b1 = ((op_t *) srcp2)[1]; | |
| 165 if (a0 != b0) | |
| 166 return CMP_LT_OR_GT (a0, b0); | |
| 167 | |
| 168 do2: | |
| 169 a0 = ((op_t *) srcp1)[2]; | |
| 170 b0 = ((op_t *) srcp2)[2]; | |
| 171 if (a1 != b1) | |
| 172 return CMP_LT_OR_GT (a1, b1); | |
| 173 | |
| 174 do1: | |
| 175 a1 = ((op_t *) srcp1)[3]; | |
| 176 b1 = ((op_t *) srcp2)[3]; | |
| 177 if (a0 != b0) | |
| 178 return CMP_LT_OR_GT (a0, b0); | |
| 179 | |
| 180 srcp1 += 4 * OPSIZ; | |
| 181 srcp2 += 4 * OPSIZ; | |
| 182 len -= 4; | |
| 183 } | |
| 184 while (len != 0); | |
| 185 | |
| 186 /* This is the right position for do0. Please don't move | |
| 187 it into the loop. */ | |
| 188 do0: | |
| 189 if (a1 != b1) | |
| 190 return CMP_LT_OR_GT (a1, b1); | |
| 191 return 0; | |
| 192 } | |
| 193 | |
| 194 /* memcmp_not_common_alignment -- Compare blocks at SRCP1 and SRCP2 with LEN | |
| 195 `op_t' objects (not LEN bytes!). SRCP2 should be aligned for memory | |
| 196 operations on `op_t', but SRCP1 *should be unaligned*. */ | |
| 197 #ifdef __GNUC__ | |
| 198 __inline | |
| 199 #endif | |
| 200 static int | |
| 1557 | 201 memcmp_not_common_alignment (long int srcp1, long int srcp2, size_t len) |
| 387 | 202 { |
| 203 op_t a0, a1, a2, a3; | |
| 204 op_t b0, b1, b2, b3; | |
| 205 op_t x; | |
| 206 int shl, shr; | |
| 207 | |
| 208 /* Calculate how to shift a word read at the memory operation | |
| 209 aligned srcp1 to make it aligned for comparison. */ | |
| 210 | |
| 211 shl = 8 * (srcp1 % OPSIZ); | |
| 212 shr = 8 * OPSIZ - shl; | |
| 213 | |
| 214 /* Make SRCP1 aligned by rounding it down to the beginning of the `op_t' | |
| 215 it points in the middle of. */ | |
| 216 srcp1 &= -OPSIZ; | |
| 217 | |
| 218 switch (len % 4) | |
| 219 { | |
| 1112 | 220 default: /* Avoid warning about uninitialized local variables. */ |
| 387 | 221 case 2: |
| 222 a1 = ((op_t *) srcp1)[0]; | |
| 223 a2 = ((op_t *) srcp1)[1]; | |
| 224 b2 = ((op_t *) srcp2)[0]; | |
| 225 srcp1 -= 1 * OPSIZ; | |
| 226 srcp2 -= 2 * OPSIZ; | |
| 227 len += 2; | |
| 228 goto do1; | |
| 229 case 3: | |
| 230 a0 = ((op_t *) srcp1)[0]; | |
| 231 a1 = ((op_t *) srcp1)[1]; | |
| 232 b1 = ((op_t *) srcp2)[0]; | |
| 233 srcp2 -= 1 * OPSIZ; | |
| 234 len += 1; | |
| 235 goto do2; | |
| 236 case 0: | |
| 237 if (OP_T_THRES <= 3 * OPSIZ && len == 0) | |
| 238 return 0; | |
| 239 a3 = ((op_t *) srcp1)[0]; | |
| 240 a0 = ((op_t *) srcp1)[1]; | |
| 241 b0 = ((op_t *) srcp2)[0]; | |
| 242 srcp1 += 1 * OPSIZ; | |
| 243 goto do3; | |
| 244 case 1: | |
| 245 a2 = ((op_t *) srcp1)[0]; | |
| 246 a3 = ((op_t *) srcp1)[1]; | |
| 247 b3 = ((op_t *) srcp2)[0]; | |
| 248 srcp1 += 2 * OPSIZ; | |
| 249 srcp2 += 1 * OPSIZ; | |
| 250 len -= 1; | |
| 251 if (OP_T_THRES <= 3 * OPSIZ && len == 0) | |
| 252 goto do0; | |
| 253 /* Fall through. */ | |
| 254 } | |
| 255 | |
| 256 do | |
| 257 { | |
| 258 a0 = ((op_t *) srcp1)[0]; | |
| 259 b0 = ((op_t *) srcp2)[0]; | |
| 260 x = MERGE(a2, shl, a3, shr); | |
| 261 if (x != b3) | |
| 262 return CMP_LT_OR_GT (x, b3); | |
| 263 | |
| 264 do3: | |
| 265 a1 = ((op_t *) srcp1)[1]; | |
| 266 b1 = ((op_t *) srcp2)[1]; | |
| 267 x = MERGE(a3, shl, a0, shr); | |
| 268 if (x != b0) | |
| 269 return CMP_LT_OR_GT (x, b0); | |
| 270 | |
| 271 do2: | |
| 272 a2 = ((op_t *) srcp1)[2]; | |
| 273 b2 = ((op_t *) srcp2)[2]; | |
| 274 x = MERGE(a0, shl, a1, shr); | |
| 275 if (x != b1) | |
| 276 return CMP_LT_OR_GT (x, b1); | |
| 277 | |
| 278 do1: | |
| 279 a3 = ((op_t *) srcp1)[3]; | |
| 280 b3 = ((op_t *) srcp2)[3]; | |
| 281 x = MERGE(a1, shl, a2, shr); | |
| 282 if (x != b2) | |
| 283 return CMP_LT_OR_GT (x, b2); | |
| 284 | |
| 285 srcp1 += 4 * OPSIZ; | |
| 286 srcp2 += 4 * OPSIZ; | |
| 287 len -= 4; | |
| 288 } | |
| 289 while (len != 0); | |
| 290 | |
| 291 /* This is the right position for do0. Please don't move | |
| 292 it into the loop. */ | |
| 293 do0: | |
| 294 x = MERGE(a2, shl, a3, shr); | |
| 295 if (x != b3) | |
| 296 return CMP_LT_OR_GT (x, b3); | |
| 297 return 0; | |
| 298 } | |
| 299 | |
| 300 int | |
| 1557 | 301 rpl_memcmp (const void *s1, const void *s2, size_t len) |
| 387 | 302 { |
| 303 op_t a0; | |
| 304 op_t b0; | |
| 305 long int srcp1 = (long int) s1; | |
| 306 long int srcp2 = (long int) s2; | |
| 307 op_t res; | |
| 308 | |
| 309 if (len >= OP_T_THRES) | |
| 310 { | |
| 311 /* There are at least some bytes to compare. No need to test | |
| 312 for LEN == 0 in this alignment loop. */ | |
| 313 while (srcp2 % OPSIZ != 0) | |
| 314 { | |
| 315 a0 = ((byte *) srcp1)[0]; | |
| 316 b0 = ((byte *) srcp2)[0]; | |
| 317 srcp1 += 1; | |
| 318 srcp2 += 1; | |
| 319 res = a0 - b0; | |
| 320 if (res != 0) | |
| 321 return res; | |
| 322 len -= 1; | |
| 323 } | |
| 324 | |
| 325 /* SRCP2 is now aligned for memory operations on `op_t'. | |
| 326 SRCP1 alignment determines if we can do a simple, | |
| 327 aligned compare or need to shuffle bits. */ | |
| 328 | |
| 329 if (srcp1 % OPSIZ == 0) | |
| 330 res = memcmp_common_alignment (srcp1, srcp2, len / OPSIZ); | |
| 331 else | |
| 332 res = memcmp_not_common_alignment (srcp1, srcp2, len / OPSIZ); | |
| 333 if (res != 0) | |
| 334 return res; | |
| 335 | |
| 336 /* Number of bytes remaining in the interval [0..OPSIZ-1]. */ | |
| 337 srcp1 += len & -OPSIZ; | |
| 338 srcp2 += len & -OPSIZ; | |
| 339 len %= OPSIZ; | |
| 340 } | |
| 341 | |
| 342 /* There are just a few bytes to compare. Use byte memory operations. */ | |
| 343 while (len != 0) | |
| 344 { | |
| 345 a0 = ((byte *) srcp1)[0]; | |
| 346 b0 = ((byte *) srcp2)[0]; | |
| 347 srcp1 += 1; | |
| 348 srcp2 += 1; | |
| 349 res = a0 - b0; | |
| 350 if (res != 0) | |
| 351 return res; | |
| 352 len -= 1; | |
| 353 } | |
| 354 | |
| 355 return 0; | |
| 356 } | |
| 776 | 357 |
| 358 #ifdef weak_alias | |
| 1112 | 359 # undef bcmp |
| 776 | 360 weak_alias (memcmp, bcmp) |
| 361 #endif |