1 /* crc32.c -- compute the CRC-32 of a data stream
2 * Copyright (C) 1995-2022 Mark Adler
3 * For conditions of distribution and use, see copyright notice in zlib.h
4 *
5 * This interleaved implementation of a CRC makes use of pipelined multiple
6 * arithmetic-logic units, commonly found in modern CPU cores. It is due to
7 * Kadatch and Jenkins (2010). See doc/crc-doc.1.0.pdf in this distribution.
8 */
9
10 /* @(#) $Id$ */
11
12 /*
13 Note on the use of DYNAMIC_CRC_TABLE: there is no mutex or semaphore
14 protection on the static variables used to control the first-use generation
15 of the crc tables. Therefore, if you #define DYNAMIC_CRC_TABLE, you should
16 first call get_crc_table() to initialize the tables before allowing more than
17 one thread to use crc32().
18
19 MAKECRCH can be #defined to write out crc32.h. A main() routine is also
20 produced, so that this one source file can be compiled to an executable.
21 */
22
23 #ifdef MAKECRCH
24 # include <stdio.h>
25 # ifndef DYNAMIC_CRC_TABLE
26 # define DYNAMIC_CRC_TABLE
27 # endif /* !DYNAMIC_CRC_TABLE */
28 #endif /* MAKECRCH */
29
30 #include "zutil.h" /* for Z_U4, Z_U8, z_crc_t, and FAR definitions */
31
32 /*
33 A CRC of a message is computed on N braids of words in the message, where
34 each word consists of W bytes (4 or 8). If N is 3, for example, then three
35 running sparse CRCs are calculated respectively on each braid, at these
36 indices in the array of words: 0, 3, 6, ..., 1, 4, 7, ..., and 2, 5, 8, ...
37 This is done starting at a word boundary, and continues until as many blocks
38 of N * W bytes as are available have been processed. The results are combined
39 into a single CRC at the end. For this code, N must be in the range 1..6 and
40 W must be 4 or 8. The upper limit on N can be increased if desired by adding
41 more #if blocks, extending the patterns apparent in the code. In addition,
42 crc32.h would need to be regenerated, if the maximum N value is increased.
43
44 N and W are chosen empirically by benchmarking the execution time on a given
45 processor. The choices for N and W below were based on testing on Intel Kaby
46 Lake i7, AMD Ryzen 7, ARM Cortex-A57, Sparc64-VII, PowerPC POWER9, and MIPS64
47 Octeon II processors. The Intel, AMD, and ARM processors were all fastest
48 with N=5, W=8. The Sparc, PowerPC, and MIPS64 were all fastest at N=5, W=4.
49 They were all tested with either gcc or clang, all using the -O3 optimization
50 level. Your mileage may vary.
51 */
52
53 /* Define N */
54 #ifdef Z_TESTN
55 # define N Z_TESTN
56 #else
57 # define N 5
58 #endif
59 #if N < 1 || N > 6
60 # error N must be in 1..6
61 #endif
62
63 /*
64 z_crc_t must be at least 32 bits. z_word_t must be at least as long as
65 z_crc_t. It is assumed here that z_word_t is either 32 bits or 64 bits, and
66 that bytes are eight bits.
67 */
68
69 /*
70 Define W and the associated z_word_t type. If W is not defined, then a
71 braided calculation is not used, and the associated tables and code are not
72 compiled.
73 */
74 #ifdef Z_TESTW
75 # if Z_TESTW-1 != -1
76 # define W Z_TESTW
77 # endif
78 #else
79 # ifdef MAKECRCH
80 # define W 8 /* required for MAKECRCH */
81 # else
82 # if defined(__x86_64__) || defined(__aarch64__)
83 # define W 8
84 # else
85 # define W 4
86 # endif
87 # endif
88 #endif
89 #ifdef W
90 # if W == 8 && defined(Z_U8)
91 typedef Z_U8 z_word_t;
92 # elif defined(Z_U4)
93 # undef W
94 # define W 4
95 typedef Z_U4 z_word_t;
96 # else
97 # undef W
98 # endif
99 #endif
100
101 /* If available, use the ARM processor CRC32 instruction. */
102 #if defined(__aarch64__) && defined(__ARM_FEATURE_CRC32) && W == 8
103 # define ARMCRC32
104 #endif
105
106 #ifndef Z_FREETYPE
107 /* Local functions. */
108 local z_crc_t multmodp OF((z_crc_t a, z_crc_t b));
109 local z_crc_t x2nmodp OF((z_off64_t n, unsigned k));
110 #endif /* Z_FREETYPE */
111
112 #if defined(W) && (!defined(ARMCRC32) || defined(DYNAMIC_CRC_TABLE))
113 local z_word_t byte_swap OF((z_word_t word));
114 #endif
115
116 #if defined(W) && !defined(ARMCRC32)
117 local z_crc_t crc_word OF((z_word_t data));
118 local z_word_t crc_word_big OF((z_word_t data));
119 #endif
120
121 #if defined(W) && (!defined(ARMCRC32) || defined(DYNAMIC_CRC_TABLE))
122 /*
123 Swap the bytes in a z_word_t to convert between little and big endian. Any
124 self-respecting compiler will optimize this to a single machine byte-swap
125 instruction, if one is available. This assumes that word_t is either 32 bits
126 or 64 bits.
127 */
128 local z_word_t byte_swap(
129 z_word_t word)
130 {
131 # if W == 8
132 return
133 (word & 0xff00000000000000) >> 56 |
134 (word & 0xff000000000000) >> 40 |
135 (word & 0xff0000000000) >> 24 |
136 (word & 0xff00000000) >> 8 |
137 (word & 0xff000000) << 8 |
138 (word & 0xff0000) << 24 |
139 (word & 0xff00) << 40 |
140 (word & 0xff) << 56;
141 # else /* W == 4 */
142 return
143 (word & 0xff000000) >> 24 |
144 (word & 0xff0000) >> 8 |
145 (word & 0xff00) << 8 |
146 (word & 0xff) << 24;
147 # endif
148 }
149 #endif
150
151 /* CRC polynomial. */
152 #define POLY 0xedb88320 /* p(x) reflected, with x^32 implied */
153
154 #ifdef DYNAMIC_CRC_TABLE
155
156 local z_crc_t FAR crc_table[256];
157 local z_crc_t FAR x2n_table[32];
158 local void make_crc_table OF((void));
159 #ifdef W
160 local z_word_t FAR crc_big_table[256];
161 local z_crc_t FAR crc_braid_table[W][256];
162 local z_word_t FAR crc_braid_big_table[W][256];
163 local void braid OF((z_crc_t [][256], z_word_t [][256], int, int));
164 #endif
165 #ifdef MAKECRCH
166 local void write_table OF((FILE *, const z_crc_t FAR *, int));
167 local void write_table32hi OF((FILE *, const z_word_t FAR *, int));
168 local void write_table64 OF((FILE *, const z_word_t FAR *, int));
169 #endif /* MAKECRCH */
170
171 /*
172 Define a once() function depending on the availability of atomics. If this is
173 compiled with DYNAMIC_CRC_TABLE defined, and if CRCs will be computed in
174 multiple threads, and if atomics are not available, then get_crc_table() must
175 be called to initialize the tables and must return before any threads are
176 allowed to compute or combine CRCs.
177 */
178
179 /* Definition of once functionality. */
180 typedef struct once_s once_t;
181 local void once OF((once_t *, void (*)(void)));
182
183 /* Check for the availability of atomics. */
184 #if defined(__STDC__) && __STDC_VERSION__ >= 201112L && \
185 !defined(__STDC_NO_ATOMICS__)
186
187 #include <stdatomic.h>
188
189 /* Structure for once(), which must be initialized with ONCE_INIT. */
190 struct once_s {
191 atomic_flag begun;
192 atomic_int done;
193 };
194 #define ONCE_INIT {ATOMIC_FLAG_INIT, 0}
195
196 /*
197 Run the provided init() function exactly once, even if multiple threads
198 invoke once() at the same time. The state must be a once_t initialized with
199 ONCE_INIT.
200 */
201 local void once(state, init)
202 once_t *state;
203 void (*init)(void);
204 {
205 if (!atomic_load(&state->done)) {
206 if (atomic_flag_test_and_set(&state->begun))
207 while (!atomic_load(&state->done))
208 ;
209 else {
210 init();
211 atomic_store(&state->done, 1);
212 }
213 }
214 }
215
216 #else /* no atomics */
217
218 /* Structure for once(), which must be initialized with ONCE_INIT. */
219 struct once_s {
220 volatile int begun;
221 volatile int done;
222 };
223 #define ONCE_INIT {0, 0}
224
225 /* Test and set. Alas, not atomic, but tries to minimize the period of
226 vulnerability. */
227 local int test_and_set OF((int volatile *));
228 local int test_and_set(
229 int volatile *flag)
230 {
231 int was;
232
233 was = *flag;
234 *flag = 1;
235 return was;
236 }
237
238 /* Run the provided init() function once. This is not thread-safe. */
239 local void once(state, init)
240 once_t *state;
241 void (*init)(void);
242 {
243 if (!state->done) {
244 if (test_and_set(&state->begun))
245 while (!state->done)
246 ;
247 else {
248 init();
249 state->done = 1;
250 }
251 }
252 }
253
254 #endif
255
256 /* State for once(). */
257 local once_t made = ONCE_INIT;
258
259 /*
260 Generate tables for a byte-wise 32-bit CRC calculation on the polynomial:
261 x^32+x^26+x^23+x^22+x^16+x^12+x^11+x^10+x^8+x^7+x^5+x^4+x^2+x+1.
262
263 Polynomials over GF(2) are represented in binary, one bit per coefficient,
264 with the lowest powers in the most significant bit. Then adding polynomials
265 is just exclusive-or, and multiplying a polynomial by x is a right shift by
266 one. If we call the above polynomial p, and represent a byte as the
267 polynomial q, also with the lowest power in the most significant bit (so the
268 byte 0xb1 is the polynomial x^7+x^3+x^2+1), then the CRC is (q*x^32) mod p,
269 where a mod b means the remainder after dividing a by b.
270
271 This calculation is done using the shift-register method of multiplying and
272 taking the remainder. The register is initialized to zero, and for each
273 incoming bit, x^32 is added mod p to the register if the bit is a one (where
274 x^32 mod p is p+x^32 = x^26+...+1), and the register is multiplied mod p by x
275 (which is shifting right by one and adding x^32 mod p if the bit shifted out
276 is a one). We start with the highest power (least significant bit) of q and
277 repeat for all eight bits of q.
278
279 The table is simply the CRC of all possible eight bit values. This is all the
280 information needed to generate CRCs on data a byte at a time for all
281 combinations of CRC register values and incoming bytes.
282 */
283
284 local void make_crc_table()
285 {
286 unsigned i, j, n;
287 z_crc_t p;
288
289 /* initialize the CRC of bytes tables */
290 for (i = 0; i < 256; i++) {
291 p = i;
292 for (j = 0; j < 8; j++)
293 p = p & 1 ? (p >> 1) ^ POLY : p >> 1;
294 crc_table[i] = p;
295 #ifdef W
296 crc_big_table[i] = byte_swap(p);
297 #endif
298 }
299
300 /* initialize the x^2^n mod p(x) table */
301 p = (z_crc_t)1 << 30; /* x^1 */
302 x2n_table[0] = p;
303 for (n = 1; n < 32; n++)
304 x2n_table[n] = p = multmodp(p, p);
305
306 #ifdef W
307 /* initialize the braiding tables -- needs x2n_table[] */
308 braid(crc_braid_table, crc_braid_big_table, N, W);
309 #endif
310
311 #ifdef MAKECRCH
312 {
313 /*
314 The crc32.h header file contains tables for both 32-bit and 64-bit
315 z_word_t's, and so requires a 64-bit type be available. In that case,
316 z_word_t must be defined to be 64-bits. This code then also generates
317 and writes out the tables for the case that z_word_t is 32 bits.
318 */
319 #if !defined(W) || W != 8
320 # error Need a 64-bit integer type in order to generate crc32.h.
321 #endif
322 FILE *out;
323 int k, n;
324 z_crc_t ltl[8][256];
325 z_word_t big[8][256];
326
327 out = fopen("crc32.h", "w");
328 if (out == NULL) return;
329
330 /* write out little-endian CRC table to crc32.h */
331 fprintf(out,
332 "/* crc32.h -- tables for rapid CRC calculation\n"
333 " * Generated automatically by crc32.c\n */\n"
334 "\n"
335 "local const z_crc_t FAR crc_table[] = {\n"
336 " ");
337 write_table(out, crc_table, 256);
338 fprintf(out,
339 "};\n");
340
341 /* write out big-endian CRC table for 64-bit z_word_t to crc32.h */
342 fprintf(out,
343 "\n"
344 "#ifdef W\n"
345 "\n"
346 "#if W == 8\n"
347 "\n"
348 "local const z_word_t FAR crc_big_table[] = {\n"
349 " ");
350 write_table64(out, crc_big_table, 256);
351 fprintf(out,
352 "};\n");
353
354 /* write out big-endian CRC table for 32-bit z_word_t to crc32.h */
355 fprintf(out,
356 "\n"
357 "#else /* W == 4 */\n"
358 "\n"
359 "local const z_word_t FAR crc_big_table[] = {\n"
360 " ");
361 write_table32hi(out, crc_big_table, 256);
362 fprintf(out,
363 "};\n"
364 "\n"
365 "#endif\n");
366
367 /* write out braid tables for each value of N */
368 for (n = 1; n <= 6; n++) {
369 fprintf(out,
370 "\n"
371 "#if N == %d\n", n);
372
373 /* compute braid tables for this N and 64-bit word_t */
374 braid(ltl, big, n, 8);
375
376 /* write out braid tables for 64-bit z_word_t to crc32.h */
377 fprintf(out,
378 "\n"
379 "#if W == 8\n"
380 "\n"
381 "local const z_crc_t FAR crc_braid_table[][256] = {\n");
382 for (k = 0; k < 8; k++) {
383 fprintf(out, " {");
384 write_table(out, ltl[k], 256);
385 fprintf(out, "}%s", k < 7 ? ",\n" : "");
386 }
387 fprintf(out,
388 "};\n"
389 "\n"
390 "local const z_word_t FAR crc_braid_big_table[][256] = {\n");
391 for (k = 0; k < 8; k++) {
392 fprintf(out, " {");
393 write_table64(out, big[k], 256);
394 fprintf(out, "}%s", k < 7 ? ",\n" : "");
395 }
396 fprintf(out,
397 "};\n");
398
399 /* compute braid tables for this N and 32-bit word_t */
400 braid(ltl, big, n, 4);
401
402 /* write out braid tables for 32-bit z_word_t to crc32.h */
403 fprintf(out,
404 "\n"
405 "#else /* W == 4 */\n"
406 "\n"
407 "local const z_crc_t FAR crc_braid_table[][256] = {\n");
408 for (k = 0; k < 4; k++) {
409 fprintf(out, " {");
410 write_table(out, ltl[k], 256);
411 fprintf(out, "}%s", k < 3 ? ",\n" : "");
412 }
413 fprintf(out,
414 "};\n"
415 "\n"
416 "local const z_word_t FAR crc_braid_big_table[][256] = {\n");
417 for (k = 0; k < 4; k++) {
418 fprintf(out, " {");
419 write_table32hi(out, big[k], 256);
420 fprintf(out, "}%s", k < 3 ? ",\n" : "");
421 }
422 fprintf(out,
423 "};\n"
424 "\n"
425 "#endif\n"
426 "\n"
427 "#endif\n");
428 }
429 fprintf(out,
430 "\n"
431 "#endif\n");
432
433 /* write out zeros operator table to crc32.h */
434 fprintf(out,
435 "\n"
436 "local const z_crc_t FAR x2n_table[] = {\n"
437 " ");
438 write_table(out, x2n_table, 32);
439 fprintf(out,
440 "};\n");
441 fclose(out);
442 }
443 #endif /* MAKECRCH */
444 }
445
446 #ifdef MAKECRCH
447
448 /*
449 Write the 32-bit values in table[0..k-1] to out, five per line in
450 hexadecimal separated by commas.
451 */
452 local void write_table(
453 FILE *out,
454 const z_crc_t FAR *table,
455 int k)
456 {
457 int n;
458
459 for (n = 0; n < k; n++)
460 fprintf(out, "%s0x%08lx%s", n == 0 || n % 5 ? "" : " ",
461 (unsigned long)(table[n]),
462 n == k - 1 ? "" : (n % 5 == 4 ? ",\n" : ", "));
463 }
464
465 /*
466 Write the high 32-bits of each value in table[0..k-1] to out, five per line
467 in hexadecimal separated by commas.
468 */
469 local void write_table32hi(
470 FILE *out,
471 const z_word_t FAR *table,
472 int k)
473 {
474 int n;
475
476 for (n = 0; n < k; n++)
477 fprintf(out, "%s0x%08lx%s", n == 0 || n % 5 ? "" : " ",
478 (unsigned long)(table[n] >> 32),
479 n == k - 1 ? "" : (n % 5 == 4 ? ",\n" : ", "));
480 }
481
482 /*
483 Write the 64-bit values in table[0..k-1] to out, three per line in
484 hexadecimal separated by commas. This assumes that if there is a 64-bit
485 type, then there is also a long long integer type, and it is at least 64
486 bits. If not, then the type cast and format string can be adjusted
487 accordingly.
488 */
489 local void write_table64(
490 FILE *out,
491 const z_word_t FAR *table,
492 int k)
493 {
494 int n;
495
496 for (n = 0; n < k; n++)
497 fprintf(out, "%s0x%016llx%s", n == 0 || n % 3 ? "" : " ",
498 (unsigned long long)(table[n]),
499 n == k - 1 ? "" : (n % 3 == 2 ? ",\n" : ", "));
500 }
501
502 /* Actually do the deed. */
503 int main()
504 {
505 make_crc_table();
506 return 0;
507 }
508
509 #endif /* MAKECRCH */
510
511 #ifdef W
512 /*
513 Generate the little and big-endian braid tables for the given n and z_word_t
514 size w. Each array must have room for w blocks of 256 elements.
515 */
516 local void braid(ltl, big, n, w)
517 z_crc_t ltl[][256];
518 z_word_t big[][256];
519 int n;
520 int w;
521 {
522 int k;
523 z_crc_t i, p, q;
524 for (k = 0; k < w; k++) {
525 p = x2nmodp((n * w + 3 - k) << 3, 0);
526 ltl[k][0] = 0;
527 big[w - 1 - k][0] = 0;
528 for (i = 1; i < 256; i++) {
529 ltl[k][i] = q = multmodp(i << 24, p);
530 big[w - 1 - k][i] = byte_swap(q);
531 }
532 }
533 }
534 #endif
535
536 #else /* !DYNAMIC_CRC_TABLE */
537 /* ========================================================================
538 * Tables for byte-wise and braided CRC-32 calculations, and a table of powers
539 * of x for combining CRC-32s, all made by make_crc_table().
540 */
541 #include "crc32.h"
542 #endif /* DYNAMIC_CRC_TABLE */
543
544 /* ========================================================================
545 * Routines used for CRC calculation. Some are also required for the table
546 * generation above.
547 */
548
549 #ifndef Z_FREETYPE
550
551 /*
552 Return a(x) multiplied by b(x) modulo p(x), where p(x) is the CRC polynomial,
553 reflected. For speed, this requires that a not be zero.
554 */
555 local z_crc_t multmodp(
556 z_crc_t a,
557 z_crc_t b)
558 {
559 z_crc_t m, p;
560
561 m = (z_crc_t)1 << 31;
562 p = 0;
563 for (;;) {
564 if (a & m) {
565 p ^= b;
566 if ((a & (m - 1)) == 0)
567 break;
568 }
569 m >>= 1;
570 b = b & 1 ? (b >> 1) ^ POLY : b >> 1;
571 }
572 return p;
573 }
574
575 /*
576 Return x^(n * 2^k) modulo p(x). Requires that x2n_table[] has been
577 initialized.
578 */
579 local z_crc_t x2nmodp(
580 z_off64_t n,
581 unsigned k)
582 {
583 z_crc_t p;
584
585 p = (z_crc_t)1 << 31; /* x^0 == 1 */
586 while (n) {
587 if (n & 1)
588 p = multmodp(x2n_table[k & 31], p);
589 n >>= 1;
590 k++;
591 }
592 return p;
593 }
594
595 /* =========================================================================
596 * This function can be used by asm versions of crc32(), and to force the
597 * generation of the CRC tables in a threaded application.
598 */
599 const z_crc_t FAR * ZEXPORT get_crc_table()
600 {
601 #ifdef DYNAMIC_CRC_TABLE
602 once(&made, make_crc_table);
603 #endif /* DYNAMIC_CRC_TABLE */
604 return (const z_crc_t FAR *)crc_table;
605 }
606
607 #endif /* Z_FREETYPE */
608
609 /* =========================================================================
610 * Use ARM machine instructions if available. This will compute the CRC about
611 * ten times faster than the braided calculation. This code does not check for
612 * the presence of the CRC instruction at run time. __ARM_FEATURE_CRC32 will
613 * only be defined if the compilation specifies an ARM processor architecture
614 * that has the instructions. For example, compiling with -march=armv8.1-a or
615 * -march=armv8-a+crc, or -march=native if the compile machine has the crc32
616 * instructions.
617 */
618 #ifdef ARMCRC32
619
620 /*
621 Constants empirically determined to maximize speed. These values are from
622 measurements on a Cortex-A57. Your mileage may vary.
623 */
624 #define Z_BATCH 3990 /* number of words in a batch */
625 #define Z_BATCH_ZEROS 0xa10d3d0c /* computed from Z_BATCH = 3990 */
626 #define Z_BATCH_MIN 800 /* fewest words in a final batch */
627
628 unsigned long ZEXPORT crc32_z(
629 unsigned long crc,
630 const unsigned char FAR *buf,
631 z_size_t len)
632 {
633 z_crc_t val;
634 z_word_t crc1, crc2;
635 const z_word_t *word;
636 z_word_t val0, val1, val2;
637 z_size_t last, last2, i;
638 z_size_t num;
639
640 /* Return initial CRC, if requested. */
641 if (buf == Z_NULL) return 0;
642
643 #ifdef DYNAMIC_CRC_TABLE
644 once(&made, make_crc_table);
645 #endif /* DYNAMIC_CRC_TABLE */
646
647 /* Pre-condition the CRC */
648 crc = (~crc) & 0xffffffff;
649
650 /* Compute the CRC up to a word boundary. */
651 while (len && ((z_size_t)buf & 7) != 0) {
652 len--;
653 val = *buf++;
654 __asm__ volatile("crc32b %w0, %w0, %w1" : "+r"(crc) : "r"(val));
655 }
656
657 /* Prepare to compute the CRC on full 64-bit words word[0..num-1]. */
658 word = (z_word_t const *)buf;
659 num = len >> 3;
660 len &= 7;
661
662 /* Do three interleaved CRCs to realize the throughput of one crc32x
663 instruction per cycle. Each CRC is calculated on Z_BATCH words. The
664 three CRCs are combined into a single CRC after each set of batches. */
665 while (num >= 3 * Z_BATCH) {
666 crc1 = 0;
667 crc2 = 0;
668 for (i = 0; i < Z_BATCH; i++) {
669 val0 = word[i];
670 val1 = word[i + Z_BATCH];
671 val2 = word[i + 2 * Z_BATCH];
672 __asm__ volatile("crc32x %w0, %w0, %x1" : "+r"(crc) : "r"(val0));
673 __asm__ volatile("crc32x %w0, %w0, %x1" : "+r"(crc1) : "r"(val1));
674 __asm__ volatile("crc32x %w0, %w0, %x1" : "+r"(crc2) : "r"(val2));
675 }
676 word += 3 * Z_BATCH;
677 num -= 3 * Z_BATCH;
678 crc = multmodp(Z_BATCH_ZEROS, crc) ^ crc1;
679 crc = multmodp(Z_BATCH_ZEROS, crc) ^ crc2;
680 }
681
682 /* Do one last smaller batch with the remaining words, if there are enough
683 to pay for the combination of CRCs. */
684 last = num / 3;
685 if (last >= Z_BATCH_MIN) {
686 last2 = last << 1;
687 crc1 = 0;
688 crc2 = 0;
689 for (i = 0; i < last; i++) {
690 val0 = word[i];
691 val1 = word[i + last];
692 val2 = word[i + last2];
693 __asm__ volatile("crc32x %w0, %w0, %x1" : "+r"(crc) : "r"(val0));
694 __asm__ volatile("crc32x %w0, %w0, %x1" : "+r"(crc1) : "r"(val1));
695 __asm__ volatile("crc32x %w0, %w0, %x1" : "+r"(crc2) : "r"(val2));
696 }
697 word += 3 * last;
698 num -= 3 * last;
699 val = x2nmodp(last, 6);
700 crc = multmodp(val, crc) ^ crc1;
701 crc = multmodp(val, crc) ^ crc2;
702 }
703
704 /* Compute the CRC on any remaining words. */
705 for (i = 0; i < num; i++) {
706 val0 = word[i];
707 __asm__ volatile("crc32x %w0, %w0, %x1" : "+r"(crc) : "r"(val0));
708 }
709 word += num;
710
711 /* Complete the CRC on any remaining bytes. */
712 buf = (const unsigned char FAR *)word;
713 while (len) {
714 len--;
715 val = *buf++;
716 __asm__ volatile("crc32b %w0, %w0, %w1" : "+r"(crc) : "r"(val));
717 }
718
719 /* Return the CRC, post-conditioned. */
720 return crc ^ 0xffffffff;
721 }
722
723 #else
724
725 #ifdef W
726
727 /*
728 Return the CRC of the W bytes in the word_t data, taking the
729 least-significant byte of the word as the first byte of data, without any pre
730 or post conditioning. This is used to combine the CRCs of each braid.
731 */
732 local z_crc_t crc_word(
733 z_word_t data)
734 {
735 int k;
736 for (k = 0; k < W; k++)
737 data = (data >> 8) ^ crc_table[data & 0xff];
738 return (z_crc_t)data;
739 }
740
741 local z_word_t crc_word_big(
742 z_word_t data)
743 {
744 int k;
745 for (k = 0; k < W; k++)
746 data = (data << 8) ^
747 crc_big_table[(data >> ((W - 1) << 3)) & 0xff];
748 return data;
749 }
750
751 #endif
752
753 /* ========================================================================= */
754 unsigned long ZEXPORT crc32_z(
755 unsigned long crc,
756 const unsigned char FAR *buf,
757 z_size_t len)
758 {
759 /* Return initial CRC, if requested. */
760 if (buf == Z_NULL) return 0;
761
762 #ifdef DYNAMIC_CRC_TABLE
763 once(&made, make_crc_table);
764 #endif /* DYNAMIC_CRC_TABLE */
765
766 /* Pre-condition the CRC */
767 crc = (~crc) & 0xffffffff;
768
769 #ifdef W
770
771 /* If provided enough bytes, do a braided CRC calculation. */
772 if (len >= N * W + W - 1) {
773 z_size_t blks;
774 z_word_t const *words;
775 unsigned endian;
776 int k;
777
778 /* Compute the CRC up to a z_word_t boundary. */
779 while (len && ((z_size_t)buf & (W - 1)) != 0) {
780 len--;
781 crc = (crc >> 8) ^ crc_table[(crc ^ *buf++) & 0xff];
782 }
783
784 /* Compute the CRC on as many N z_word_t blocks as are available. */
785 blks = len / (N * W);
786 len -= blks * N * W;
787 words = (z_word_t const *)buf;
788
789 /* Do endian check at execution time instead of compile time, since ARM
790 processors can change the endianess at execution time. If the
791 compiler knows what the endianess will be, it can optimize out the
792 check and the unused branch. */
793 endian = 1;
794 if (*(unsigned char *)&endian) {
795 /* Little endian. */
796
797 z_crc_t crc0;
798 z_word_t word0;
799 #if N > 1
800 z_crc_t crc1;
801 z_word_t word1;
802 #if N > 2
803 z_crc_t crc2;
804 z_word_t word2;
805 #if N > 3
806 z_crc_t crc3;
807 z_word_t word3;
808 #if N > 4
809 z_crc_t crc4;
810 z_word_t word4;
811 #if N > 5
812 z_crc_t crc5;
813 z_word_t word5;
814 #endif
815 #endif
816 #endif
817 #endif
818 #endif
819
820 /* Initialize the CRC for each braid. */
821 crc0 = crc;
822 #if N > 1
823 crc1 = 0;
824 #if N > 2
825 crc2 = 0;
826 #if N > 3
827 crc3 = 0;
828 #if N > 4
829 crc4 = 0;
830 #if N > 5
831 crc5 = 0;
832 #endif
833 #endif
834 #endif
835 #endif
836 #endif
837
838 /*
839 Process the first blks-1 blocks, computing the CRCs on each braid
840 independently.
841 */
842 while (--blks) {
843 /* Load the word for each braid into registers. */
844 word0 = crc0 ^ words[0];
845 #if N > 1
846 word1 = crc1 ^ words[1];
847 #if N > 2
848 word2 = crc2 ^ words[2];
849 #if N > 3
850 word3 = crc3 ^ words[3];
851 #if N > 4
852 word4 = crc4 ^ words[4];
853 #if N > 5
854 word5 = crc5 ^ words[5];
855 #endif
856 #endif
857 #endif
858 #endif
859 #endif
860 words += N;
861
862 /* Compute and update the CRC for each word. The loop should
863 get unrolled. */
864 crc0 = crc_braid_table[0][word0 & 0xff];
865 #if N > 1
866 crc1 = crc_braid_table[0][word1 & 0xff];
867 #if N > 2
868 crc2 = crc_braid_table[0][word2 & 0xff];
869 #if N > 3
870 crc3 = crc_braid_table[0][word3 & 0xff];
871 #if N > 4
872 crc4 = crc_braid_table[0][word4 & 0xff];
873 #if N > 5
874 crc5 = crc_braid_table[0][word5 & 0xff];
875 #endif
876 #endif
877 #endif
878 #endif
879 #endif
880 for (k = 1; k < W; k++) {
881 crc0 ^= crc_braid_table[k][(word0 >> (k << 3)) & 0xff];
882 #if N > 1
883 crc1 ^= crc_braid_table[k][(word1 >> (k << 3)) & 0xff];
884 #if N > 2
885 crc2 ^= crc_braid_table[k][(word2 >> (k << 3)) & 0xff];
886 #if N > 3
887 crc3 ^= crc_braid_table[k][(word3 >> (k << 3)) & 0xff];
888 #if N > 4
889 crc4 ^= crc_braid_table[k][(word4 >> (k << 3)) & 0xff];
890 #if N > 5
891 crc5 ^= crc_braid_table[k][(word5 >> (k << 3)) & 0xff];
892 #endif
893 #endif
894 #endif
895 #endif
896 #endif
897 }
898 }
899
900 /*
901 Process the last block, combining the CRCs of the N braids at the
902 same time.
903 */
904 crc = crc_word(crc0 ^ words[0]);
905 #if N > 1
906 crc = crc_word(crc1 ^ words[1] ^ crc);
907 #if N > 2
908 crc = crc_word(crc2 ^ words[2] ^ crc);
909 #if N > 3
910 crc = crc_word(crc3 ^ words[3] ^ crc);
911 #if N > 4
912 crc = crc_word(crc4 ^ words[4] ^ crc);
913 #if N > 5
914 crc = crc_word(crc5 ^ words[5] ^ crc);
915 #endif
916 #endif
917 #endif
918 #endif
919 #endif
920 words += N;
921 }
922 else {
923 /* Big endian. */
924
925 z_word_t crc0, word0, comb;
926 #if N > 1
927 z_word_t crc1, word1;
928 #if N > 2
929 z_word_t crc2, word2;
930 #if N > 3
931 z_word_t crc3, word3;
932 #if N > 4
933 z_word_t crc4, word4;
934 #if N > 5
935 z_word_t crc5, word5;
936 #endif
937 #endif
938 #endif
939 #endif
940 #endif
941
942 /* Initialize the CRC for each braid. */
943 crc0 = byte_swap(crc);
944 #if N > 1
945 crc1 = 0;
946 #if N > 2
947 crc2 = 0;
948 #if N > 3
949 crc3 = 0;
950 #if N > 4
951 crc4 = 0;
952 #if N > 5
953 crc5 = 0;
954 #endif
955 #endif
956 #endif
957 #endif
958 #endif
959
960 /*
961 Process the first blks-1 blocks, computing the CRCs on each braid
962 independently.
963 */
964 while (--blks) {
965 /* Load the word for each braid into registers. */
966 word0 = crc0 ^ words[0];
967 #if N > 1
968 word1 = crc1 ^ words[1];
969 #if N > 2
970 word2 = crc2 ^ words[2];
971 #if N > 3
972 word3 = crc3 ^ words[3];
973 #if N > 4
974 word4 = crc4 ^ words[4];
975 #if N > 5
976 word5 = crc5 ^ words[5];
977 #endif
978 #endif
979 #endif
980 #endif
981 #endif
982 words += N;
983
984 /* Compute and update the CRC for each word. The loop should
985 get unrolled. */
986 crc0 = crc_braid_big_table[0][word0 & 0xff];
987 #if N > 1
988 crc1 = crc_braid_big_table[0][word1 & 0xff];
989 #if N > 2
990 crc2 = crc_braid_big_table[0][word2 & 0xff];
991 #if N > 3
992 crc3 = crc_braid_big_table[0][word3 & 0xff];
993 #if N > 4
994 crc4 = crc_braid_big_table[0][word4 & 0xff];
995 #if N > 5
996 crc5 = crc_braid_big_table[0][word5 & 0xff];
997 #endif
998 #endif
999 #endif
1000 #endif
1001 #endif
1002 for (k = 1; k < W; k++) {
1003 crc0 ^= crc_braid_big_table[k][(word0 >> (k << 3)) & 0xff];
1004 #if N > 1
1005 crc1 ^= crc_braid_big_table[k][(word1 >> (k << 3)) & 0xff];
1006 #if N > 2
1007 crc2 ^= crc_braid_big_table[k][(word2 >> (k << 3)) & 0xff];
1008 #if N > 3
1009 crc3 ^= crc_braid_big_table[k][(word3 >> (k << 3)) & 0xff];
1010 #if N > 4
1011 crc4 ^= crc_braid_big_table[k][(word4 >> (k << 3)) & 0xff];
1012 #if N > 5
1013 crc5 ^= crc_braid_big_table[k][(word5 >> (k << 3)) & 0xff];
1014 #endif
1015 #endif
1016 #endif
1017 #endif
1018 #endif
1019 }
1020 }
1021
1022 /*
1023 Process the last block, combining the CRCs of the N braids at the
1024 same time.
1025 */
1026 comb = crc_word_big(crc0 ^ words[0]);
1027 #if N > 1
1028 comb = crc_word_big(crc1 ^ words[1] ^ comb);
1029 #if N > 2
1030 comb = crc_word_big(crc2 ^ words[2] ^ comb);
1031 #if N > 3
1032 comb = crc_word_big(crc3 ^ words[3] ^ comb);
1033 #if N > 4
1034 comb = crc_word_big(crc4 ^ words[4] ^ comb);
1035 #if N > 5
1036 comb = crc_word_big(crc5 ^ words[5] ^ comb);
1037 #endif
1038 #endif
1039 #endif
1040 #endif
1041 #endif
1042 words += N;
1043 crc = byte_swap(comb);
1044 }
1045
1046 /*
1047 Update the pointer to the remaining bytes to process.
1048 */
1049 buf = (unsigned char const *)words;
1050 }
1051
1052 #endif /* W */
1053
1054 /* Complete the computation of the CRC on any remaining bytes. */
1055 while (len >= 8) {
1056 len -= 8;
1057 crc = (crc >> 8) ^ crc_table[(crc ^ *buf++) & 0xff];
1058 crc = (crc >> 8) ^ crc_table[(crc ^ *buf++) & 0xff];
1059 crc = (crc >> 8) ^ crc_table[(crc ^ *buf++) & 0xff];
1060 crc = (crc >> 8) ^ crc_table[(crc ^ *buf++) & 0xff];
1061 crc = (crc >> 8) ^ crc_table[(crc ^ *buf++) & 0xff];
1062 crc = (crc >> 8) ^ crc_table[(crc ^ *buf++) & 0xff];
1063 crc = (crc >> 8) ^ crc_table[(crc ^ *buf++) & 0xff];
1064 crc = (crc >> 8) ^ crc_table[(crc ^ *buf++) & 0xff];
1065 }
1066 while (len) {
1067 len--;
1068 crc = (crc >> 8) ^ crc_table[(crc ^ *buf++) & 0xff];
1069 }
1070
1071 /* Return the CRC, post-conditioned. */
1072 return crc ^ 0xffffffff;
1073 }
1074
1075 #endif
1076
1077 /* ========================================================================= */
1078 unsigned long ZEXPORT crc32(
1079 unsigned long crc,
1080 const unsigned char FAR *buf,
1081 uInt len)
1082 {
1083 return crc32_z(crc, buf, len);
1084 }
1085
1086 #ifndef Z_FREETYPE
1087
1088 /* ========================================================================= */
1089 uLong ZEXPORT crc32_combine64(
1090 uLong crc1,
1091 uLong crc2,
1092 z_off64_t len2)
1093 {
1094 #ifdef DYNAMIC_CRC_TABLE
1095 once(&made, make_crc_table);
1096 #endif /* DYNAMIC_CRC_TABLE */
1097 return multmodp(x2nmodp(len2, 3), crc1) ^ (crc2 & 0xffffffff);
1098 }
1099
1100 /* ========================================================================= */
1101 uLong ZEXPORT crc32_combine(
1102 uLong crc1,
1103 uLong crc2,
1104 z_off_t len2)
1105 {
1106 return crc32_combine64(crc1, crc2, (z_off64_t)len2);
1107 }
1108
1109 /* ========================================================================= */
1110 uLong ZEXPORT crc32_combine_gen64(
1111 z_off64_t len2)
1112 {
1113 #ifdef DYNAMIC_CRC_TABLE
1114 once(&made, make_crc_table);
1115 #endif /* DYNAMIC_CRC_TABLE */
1116 return x2nmodp(len2, 3);
1117 }
1118
1119 /* ========================================================================= */
1120 uLong ZEXPORT crc32_combine_gen(
1121 z_off_t len2)
1122 {
1123 return crc32_combine_gen64((z_off64_t)len2);
1124 }
1125
1126 /* ========================================================================= */
1127 uLong ZEXPORT crc32_combine_op(
1128 uLong crc1,
1129 uLong crc2,
1130 uLong op)
1131 {
1132 return multmodp(op, crc1) ^ (crc2 & 0xffffffff);
1133 }
1134
1135 #endif /* Z_FREETYPE */