/* crc32.c -- compute the CRC-32 of a data stream
- * Copyright (C) 1995 Mark Adler
- * For conditions of distribution and use, see copyright notice in zlib.h
+ * Copyright (C) 1995-2022 Mark Adler
+ * For conditions of distribution and use, see copyright notice in zlib.h
+ *
+ * This interleaved implementation of a CRC makes use of pipelined multiple
+ * arithmetic-logic units, commonly found in modern CPU cores. It is due to
+ * Kadatch and Jenkins (2010). See doc/crc-doc.1.0.pdf in this distribution.
*/
-/* $Id: crc32.c,v 1.4 1995/04/14 14:55:12 jloup Exp $ */
+/* @(#) $Id$ */
-#include "zlib.h"
+/*
+ Note on the use of DYNAMIC_CRC_TABLE: there is no mutex or semaphore
+ protection on the static variables used to control the first-use generation
+ of the crc tables. Therefore, if you #define DYNAMIC_CRC_TABLE, you should
+ first call get_crc_table() to initialize the tables before allowing more than
+ one thread to use crc32().
-#define local static
+ MAKECRCH can be #defined to write out crc32.h. A main() routine is also
+ produced, so that this one source file can be compiled to an executable.
+ */
+
+#ifdef MAKECRCH
+# include <stdio.h>
+# ifndef DYNAMIC_CRC_TABLE
+# define DYNAMIC_CRC_TABLE
+# endif /* !DYNAMIC_CRC_TABLE */
+#endif /* MAKECRCH */
+
+#include "zutil.h" /* for Z_U4, Z_U8, z_crc_t, and FAR definitions */
+
+ /*
+ A CRC of a message is computed on N braids of words in the message, where
+ each word consists of W bytes (4 or 8). If N is 3, for example, then three
+ running sparse CRCs are calculated respectively on each braid, at these
+ indices in the array of words: 0, 3, 6, ..., 1, 4, 7, ..., and 2, 5, 8, ...
+ This is done starting at a word boundary, and continues until as many blocks
+ of N * W bytes as are available have been processed. The results are combined
+ into a single CRC at the end. For this code, N must be in the range 1..6 and
+ W must be 4 or 8. The upper limit on N can be increased if desired by adding
+ more #if blocks, extending the patterns apparent in the code. In addition,
+ crc32.h would need to be regenerated, if the maximum N value is increased.
+
+ N and W are chosen empirically by benchmarking the execution time on a given
+ processor. The choices for N and W below were based on testing on Intel Kaby
+ Lake i7, AMD Ryzen 7, ARM Cortex-A57, Sparc64-VII, PowerPC POWER9, and MIPS64
+ Octeon II processors. The Intel, AMD, and ARM processors were all fastest
+ with N=5, W=8. The Sparc, PowerPC, and MIPS64 were all fastest at N=5, W=4.
+ They were all tested with either gcc or clang, all using the -O3 optimization
+ level. Your mileage may vary.
+ */
+
+/* Define N */
+#ifdef Z_TESTN
+# define N Z_TESTN
+#else
+# define N 5
+#endif
+#if N < 1 || N > 6
+# error N must be in 1..6
+#endif
+
+/*
+ z_crc_t must be at least 32 bits. z_word_t must be at least as long as
+ z_crc_t. It is assumed here that z_word_t is either 32 bits or 64 bits, and
+ that bytes are eight bits.
+ */
+
+/*
+ Define W and the associated z_word_t type. If W is not defined, then a
+ braided calculation is not used, and the associated tables and code are not
+ compiled.
+ */
+#ifdef Z_TESTW
+# if Z_TESTW-1 != -1
+# define W Z_TESTW
+# endif
+#else
+# ifdef MAKECRCH
+# define W 8 /* required for MAKECRCH */
+# else
+# if defined(__x86_64__) || defined(__aarch64__)
+# define W 8
+# else
+# define W 4
+# endif
+# endif
+#endif
+#ifdef W
+# if W == 8 && defined(Z_U8)
+ typedef Z_U8 z_word_t;
+# elif defined(Z_U4)
+# undef W
+# define W 4
+ typedef Z_U4 z_word_t;
+# else
+# undef W
+# endif
+#endif
+
+/* Local functions. */
+local z_crc_t multmodp OF((z_crc_t a, z_crc_t b));
+local z_crc_t x2nmodp OF((z_off64_t n, unsigned k));
+
+/* If available, use the ARM processor CRC32 instruction. */
+#if defined(__aarch64__) && defined(__ARM_FEATURE_CRC32) && W == 8
+# define ARMCRC32
+#endif
+
+#if defined(W) && (!defined(ARMCRC32) || defined(DYNAMIC_CRC_TABLE))
+/*
+ Swap the bytes in a z_word_t to convert between little and big endian. Any
+ self-respecting compiler will optimize this to a single machine byte-swap
+ instruction, if one is available. This assumes that word_t is either 32 bits
+ or 64 bits.
+ */
+local z_word_t byte_swap(word)
+ z_word_t word;
+{
+# if W == 8
+ return
+ (word & 0xff00000000000000) >> 56 |
+ (word & 0xff000000000000) >> 40 |
+ (word & 0xff0000000000) >> 24 |
+ (word & 0xff00000000) >> 8 |
+ (word & 0xff000000) << 8 |
+ (word & 0xff0000) << 24 |
+ (word & 0xff00) << 40 |
+ (word & 0xff) << 56;
+# else /* W == 4 */
+ return
+ (word & 0xff000000) >> 24 |
+ (word & 0xff0000) >> 8 |
+ (word & 0xff00) << 8 |
+ (word & 0xff) << 24;
+# endif
+}
+#endif
+
+/* CRC polynomial. */
+#define POLY 0xedb88320 /* p(x) reflected, with x^32 implied */
#ifdef DYNAMIC_CRC_TABLE
-/* =========================================================================
- * Make the crc table. This function is needed only if you want to compute
- * the table dynamically.
+
+local z_crc_t FAR crc_table[256];
+local z_crc_t FAR x2n_table[32];
+local void make_crc_table OF((void));
+#ifdef W
+ local z_word_t FAR crc_big_table[256];
+ local z_crc_t FAR crc_braid_table[W][256];
+ local z_word_t FAR crc_braid_big_table[W][256];
+ local void braid OF((z_crc_t [][256], z_word_t [][256], int, int));
+#endif
+#ifdef MAKECRCH
+ local void write_table OF((FILE *, const z_crc_t FAR *, int));
+ local void write_table32hi OF((FILE *, const z_word_t FAR *, int));
+ local void write_table64 OF((FILE *, const z_word_t FAR *, int));
+#endif /* MAKECRCH */
+
+/*
+ Define a once() function depending on the availability of atomics. If this is
+ compiled with DYNAMIC_CRC_TABLE defined, and if CRCs will be computed in
+ multiple threads, and if atomics are not available, then get_crc_table() must
+ be called to initialize the tables and must return before any threads are
+ allowed to compute or combine CRCs.
*/
-local int crc_table_empty = 1;
-local uLong crc_table[256];
-local void make_crc_table()
+/* Definition of once functionality. */
+typedef struct once_s once_t;
+local void once OF((once_t *, void (*)(void)));
+
+/* Check for the availability of atomics. */
+#if defined(__STDC__) && __STDC_VERSION__ >= 201112L && \
+ !defined(__STDC_NO_ATOMICS__)
+
+#include <stdatomic.h>
+
+/* Structure for once(), which must be initialized with ONCE_INIT. */
+struct once_s {
+ atomic_flag begun;
+ atomic_int done;
+};
+#define ONCE_INIT {ATOMIC_FLAG_INIT, 0}
+
+/*
+ Run the provided init() function exactly once, even if multiple threads
+ invoke once() at the same time. The state must be a once_t initialized with
+ ONCE_INIT.
+ */
+local void once(state, init)
+ once_t *state;
+ void (*init)(void);
{
- uLong c;
- int n, k;
-
- for (n = 0; n < 256; n++)
- {
- c = (uLong)n;
- for (k = 0; k < 8; k++)
- c = c & 1 ? 0xedb88320L ^ (c >> 1) : c >> 1;
- crc_table[n] = c;
- }
- crc_table_empty = 0;
+ if (!atomic_load(&state->done)) {
+ if (atomic_flag_test_and_set(&state->begun))
+ while (!atomic_load(&state->done))
+ ;
+ else {
+ init();
+ atomic_store(&state->done, 1);
+ }
+ }
}
-#else
-/* ========================================================================
- * Table of CRC-32's of all single-byte values (made by make_crc_table)
- */
-local uLong crc_table[] = {
- 0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L,
- 0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L,
- 0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L,
- 0x90bf1d91L, 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL,
- 0x1adad47dL, 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L, 0x136c9856L,
- 0x646ba8c0L, 0xfd62f97aL, 0x8a65c9ecL, 0x14015c4fL, 0x63066cd9L,
- 0xfa0f3d63L, 0x8d080df5L, 0x3b6e20c8L, 0x4c69105eL, 0xd56041e4L,
- 0xa2677172L, 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL, 0xa50ab56bL,
- 0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L, 0x32d86ce3L,
- 0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L, 0x26d930acL, 0x51de003aL,
- 0xc8d75180L, 0xbfd06116L, 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L,
- 0xb8bda50fL, 0x2802b89eL, 0x5f058808L, 0xc60cd9b2L, 0xb10be924L,
- 0x2f6f7c87L, 0x58684c11L, 0xc1611dabL, 0xb6662d3dL, 0x76dc4190L,
- 0x01db7106L, 0x98d220bcL, 0xefd5102aL, 0x71b18589L, 0x06b6b51fL,
- 0x9fbfe4a5L, 0xe8b8d433L, 0x7807c9a2L, 0x0f00f934L, 0x9609a88eL,
- 0xe10e9818L, 0x7f6a0dbbL, 0x086d3d2dL, 0x91646c97L, 0xe6635c01L,
- 0x6b6b51f4L, 0x1c6c6162L, 0x856530d8L, 0xf262004eL, 0x6c0695edL,
- 0x1b01a57bL, 0x8208f4c1L, 0xf50fc457L, 0x65b0d9c6L, 0x12b7e950L,
- 0x8bbeb8eaL, 0xfcb9887cL, 0x62dd1ddfL, 0x15da2d49L, 0x8cd37cf3L,
- 0xfbd44c65L, 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L, 0xd4bb30e2L,
- 0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL, 0x4369e96aL,
- 0x346ed9fcL, 0xad678846L, 0xda60b8d0L, 0x44042d73L, 0x33031de5L,
- 0xaa0a4c5fL, 0xdd0d7cc9L, 0x5005713cL, 0x270241aaL, 0xbe0b1010L,
- 0xc90c2086L, 0x5768b525L, 0x206f85b3L, 0xb966d409L, 0xce61e49fL,
- 0x5edef90eL, 0x29d9c998L, 0xb0d09822L, 0xc7d7a8b4L, 0x59b33d17L,
- 0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL, 0xedb88320L, 0x9abfb3b6L,
- 0x03b6e20cL, 0x74b1d29aL, 0xead54739L, 0x9dd277afL, 0x04db2615L,
- 0x73dc1683L, 0xe3630b12L, 0x94643b84L, 0x0d6d6a3eL, 0x7a6a5aa8L,
- 0xe40ecf0bL, 0x9309ff9dL, 0x0a00ae27L, 0x7d079eb1L, 0xf00f9344L,
- 0x8708a3d2L, 0x1e01f268L, 0x6906c2feL, 0xf762575dL, 0x806567cbL,
- 0x196c3671L, 0x6e6b06e7L, 0xfed41b76L, 0x89d32be0L, 0x10da7a5aL,
- 0x67dd4accL, 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L, 0x60b08ed5L,
- 0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L, 0xd1bb67f1L,
- 0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL, 0xd80d2bdaL, 0xaf0a1b4cL,
- 0x36034af6L, 0x41047a60L, 0xdf60efc3L, 0xa867df55L, 0x316e8eefL,
- 0x4669be79L, 0xcb61b38cL, 0xbc66831aL, 0x256fd2a0L, 0x5268e236L,
- 0xcc0c7795L, 0xbb0b4703L, 0x220216b9L, 0x5505262fL, 0xc5ba3bbeL,
- 0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L, 0xc2d7ffa7L, 0xb5d0cf31L,
- 0x2cd99e8bL, 0x5bdeae1dL, 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL,
- 0x026d930aL, 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x05005713L,
- 0x95bf4a82L, 0xe2b87a14L, 0x7bb12baeL, 0x0cb61b38L, 0x92d28e9bL,
- 0xe5d5be0dL, 0x7cdcefb7L, 0x0bdbdf21L, 0x86d3d2d4L, 0xf1d4e242L,
- 0x68ddb3f8L, 0x1fda836eL, 0x81be16cdL, 0xf6b9265bL, 0x6fb077e1L,
- 0x18b74777L, 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL, 0x11010b5cL,
- 0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L, 0xa00ae278L,
- 0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L, 0xa7672661L, 0xd06016f7L,
- 0x4969474dL, 0x3e6e77dbL, 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L,
- 0x37d83bf0L, 0xa9bcae53L, 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L,
- 0xbdbdf21cL, 0xcabac28aL, 0x53b39330L, 0x24b4a3a6L, 0xbad03605L,
- 0xcdd70693L, 0x54de5729L, 0x23d967bfL, 0xb3667a2eL, 0xc4614ab8L,
- 0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL,
- 0x2d02ef8dL
+
+#else /* no atomics */
+
+/* Structure for once(), which must be initialized with ONCE_INIT. */
+struct once_s {
+ volatile int begun;
+ volatile int done;
};
+#define ONCE_INIT {0, 0}
+
+/* Test and set. Alas, not atomic, but tries to minimize the period of
+ vulnerability. */
+local int test_and_set OF((int volatile *));
+local int test_and_set(flag)
+ int volatile *flag;
+{
+ int was;
+
+ was = *flag;
+ *flag = 1;
+ return was;
+}
+
+/* Run the provided init() function once. This is not thread-safe. */
+local void once(state, init)
+ once_t *state;
+ void (*init)(void);
+{
+ if (!state->done) {
+ if (test_and_set(&state->begun))
+ while (!state->done)
+ ;
+ else {
+ init();
+ state->done = 1;
+ }
+ }
+}
+
+#endif
+
+/* State for once(). */
+local once_t made = ONCE_INIT;
+
+/*
+ Generate tables for a byte-wise 32-bit CRC calculation on the polynomial:
+ 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.
+
+ Polynomials over GF(2) are represented in binary, one bit per coefficient,
+ with the lowest powers in the most significant bit. Then adding polynomials
+ is just exclusive-or, and multiplying a polynomial by x is a right shift by
+ one. If we call the above polynomial p, and represent a byte as the
+ polynomial q, also with the lowest power in the most significant bit (so the
+ byte 0xb1 is the polynomial x^7+x^3+x^2+1), then the CRC is (q*x^32) mod p,
+ where a mod b means the remainder after dividing a by b.
+
+ This calculation is done using the shift-register method of multiplying and
+ taking the remainder. The register is initialized to zero, and for each
+ incoming bit, x^32 is added mod p to the register if the bit is a one (where
+ x^32 mod p is p+x^32 = x^26+...+1), and the register is multiplied mod p by x
+ (which is shifting right by one and adding x^32 mod p if the bit shifted out
+ is a one). We start with the highest power (least significant bit) of q and
+ repeat for all eight bits of q.
+
+ The table is simply the CRC of all possible eight bit values. This is all the
+ information needed to generate CRCs on data a byte at a time for all
+ combinations of CRC register values and incoming bytes.
+ */
+
+local void make_crc_table()
+{
+ unsigned i, j, n;
+ z_crc_t p;
+
+ /* initialize the CRC of bytes tables */
+ for (i = 0; i < 256; i++) {
+ p = i;
+ for (j = 0; j < 8; j++)
+ p = p & 1 ? (p >> 1) ^ POLY : p >> 1;
+ crc_table[i] = p;
+#ifdef W
+ crc_big_table[i] = byte_swap(p);
+#endif
+ }
+
+ /* initialize the x^2^n mod p(x) table */
+ p = (z_crc_t)1 << 30; /* x^1 */
+ x2n_table[0] = p;
+ for (n = 1; n < 32; n++)
+ x2n_table[n] = p = multmodp(p, p);
+
+#ifdef W
+ /* initialize the braiding tables -- needs x2n_table[] */
+ braid(crc_braid_table, crc_braid_big_table, N, W);
+#endif
+
+#ifdef MAKECRCH
+ {
+ /*
+ The crc32.h header file contains tables for both 32-bit and 64-bit
+ z_word_t's, and so requires a 64-bit type be available. In that case,
+ z_word_t must be defined to be 64-bits. This code then also generates
+ and writes out the tables for the case that z_word_t is 32 bits.
+ */
+#if !defined(W) || W != 8
+# error Need a 64-bit integer type in order to generate crc32.h.
+#endif
+ FILE *out;
+ int k, n;
+ z_crc_t ltl[8][256];
+ z_word_t big[8][256];
+
+ out = fopen("crc32.h", "w");
+ if (out == NULL) return;
+
+ /* write out little-endian CRC table to crc32.h */
+ fprintf(out,
+ "/* crc32.h -- tables for rapid CRC calculation\n"
+ " * Generated automatically by crc32.c\n */\n"
+ "\n"
+ "local const z_crc_t FAR crc_table[] = {\n"
+ " ");
+ write_table(out, crc_table, 256);
+ fprintf(out,
+ "};\n");
+
+ /* write out big-endian CRC table for 64-bit z_word_t to crc32.h */
+ fprintf(out,
+ "\n"
+ "#ifdef W\n"
+ "\n"
+ "#if W == 8\n"
+ "\n"
+ "local const z_word_t FAR crc_big_table[] = {\n"
+ " ");
+ write_table64(out, crc_big_table, 256);
+ fprintf(out,
+ "};\n");
+
+ /* write out big-endian CRC table for 32-bit z_word_t to crc32.h */
+ fprintf(out,
+ "\n"
+ "#else /* W == 4 */\n"
+ "\n"
+ "local const z_word_t FAR crc_big_table[] = {\n"
+ " ");
+ write_table32hi(out, crc_big_table, 256);
+ fprintf(out,
+ "};\n"
+ "\n"
+ "#endif\n");
+
+ /* write out braid tables for each value of N */
+ for (n = 1; n <= 6; n++) {
+ fprintf(out,
+ "\n"
+ "#if N == %d\n", n);
+
+ /* compute braid tables for this N and 64-bit word_t */
+ braid(ltl, big, n, 8);
+
+ /* write out braid tables for 64-bit z_word_t to crc32.h */
+ fprintf(out,
+ "\n"
+ "#if W == 8\n"
+ "\n"
+ "local const z_crc_t FAR crc_braid_table[][256] = {\n");
+ for (k = 0; k < 8; k++) {
+ fprintf(out, " {");
+ write_table(out, ltl[k], 256);
+ fprintf(out, "}%s", k < 7 ? ",\n" : "");
+ }
+ fprintf(out,
+ "};\n"
+ "\n"
+ "local const z_word_t FAR crc_braid_big_table[][256] = {\n");
+ for (k = 0; k < 8; k++) {
+ fprintf(out, " {");
+ write_table64(out, big[k], 256);
+ fprintf(out, "}%s", k < 7 ? ",\n" : "");
+ }
+ fprintf(out,
+ "};\n");
+
+ /* compute braid tables for this N and 32-bit word_t */
+ braid(ltl, big, n, 4);
+
+ /* write out braid tables for 32-bit z_word_t to crc32.h */
+ fprintf(out,
+ "\n"
+ "#else /* W == 4 */\n"
+ "\n"
+ "local const z_crc_t FAR crc_braid_table[][256] = {\n");
+ for (k = 0; k < 4; k++) {
+ fprintf(out, " {");
+ write_table(out, ltl[k], 256);
+ fprintf(out, "}%s", k < 3 ? ",\n" : "");
+ }
+ fprintf(out,
+ "};\n"
+ "\n"
+ "local const z_word_t FAR crc_braid_big_table[][256] = {\n");
+ for (k = 0; k < 4; k++) {
+ fprintf(out, " {");
+ write_table32hi(out, big[k], 256);
+ fprintf(out, "}%s", k < 3 ? ",\n" : "");
+ }
+ fprintf(out,
+ "};\n"
+ "\n"
+ "#endif\n"
+ "\n"
+ "#endif\n");
+ }
+ fprintf(out,
+ "\n"
+ "#endif\n");
+
+ /* write out zeros operator table to crc32.h */
+ fprintf(out,
+ "\n"
+ "local const z_crc_t FAR x2n_table[] = {\n"
+ " ");
+ write_table(out, x2n_table, 32);
+ fprintf(out,
+ "};\n");
+ fclose(out);
+ }
+#endif /* MAKECRCH */
+}
+
+#ifdef MAKECRCH
+
+/*
+ Write the 32-bit values in table[0..k-1] to out, five per line in
+ hexadecimal separated by commas.
+ */
+local void write_table(out, table, k)
+ FILE *out;
+ const z_crc_t FAR *table;
+ int k;
+{
+ int n;
+
+ for (n = 0; n < k; n++)
+ fprintf(out, "%s0x%08lx%s", n == 0 || n % 5 ? "" : " ",
+ (unsigned long)(table[n]),
+ n == k - 1 ? "" : (n % 5 == 4 ? ",\n" : ", "));
+}
+
+/*
+ Write the high 32-bits of each value in table[0..k-1] to out, five per line
+ in hexadecimal separated by commas.
+ */
+local void write_table32hi(out, table, k)
+FILE *out;
+const z_word_t FAR *table;
+int k;
+{
+ int n;
+
+ for (n = 0; n < k; n++)
+ fprintf(out, "%s0x%08lx%s", n == 0 || n % 5 ? "" : " ",
+ (unsigned long)(table[n] >> 32),
+ n == k - 1 ? "" : (n % 5 == 4 ? ",\n" : ", "));
+}
+
+/*
+ Write the 64-bit values in table[0..k-1] to out, three per line in
+ hexadecimal separated by commas. This assumes that if there is a 64-bit
+ type, then there is also a long long integer type, and it is at least 64
+ bits. If not, then the type cast and format string can be adjusted
+ accordingly.
+ */
+local void write_table64(out, table, k)
+ FILE *out;
+ const z_word_t FAR *table;
+ int k;
+{
+ int n;
+
+ for (n = 0; n < k; n++)
+ fprintf(out, "%s0x%016llx%s", n == 0 || n % 3 ? "" : " ",
+ (unsigned long long)(table[n]),
+ n == k - 1 ? "" : (n % 3 == 2 ? ",\n" : ", "));
+}
+
+/* Actually do the deed. */
+int main()
+{
+ make_crc_table();
+ return 0;
+}
+
+#endif /* MAKECRCH */
+
+#ifdef W
+/*
+ Generate the little and big-endian braid tables for the given n and z_word_t
+ size w. Each array must have room for w blocks of 256 elements.
+ */
+local void braid(ltl, big, n, w)
+ z_crc_t ltl[][256];
+ z_word_t big[][256];
+ int n;
+ int w;
+{
+ int k;
+ z_crc_t i, p, q;
+ for (k = 0; k < w; k++) {
+ p = x2nmodp((n * w + 3 - k) << 3, 0);
+ ltl[k][0] = 0;
+ big[w - 1 - k][0] = 0;
+ for (i = 1; i < 256; i++) {
+ ltl[k][i] = q = multmodp(i << 24, p);
+ big[w - 1 - k][i] = byte_swap(q);
+ }
+ }
+}
#endif
-#define DO1(buf) crc = crc_table[((int)crc ^ (*buf++)) & 0xff] ^ (crc >> 8);
-#define DO2(buf) DO1(buf); DO1(buf);
-#define DO4(buf) DO2(buf); DO2(buf);
-#define DO8(buf) DO4(buf); DO4(buf);
+#else /* !DYNAMIC_CRC_TABLE */
+/* ========================================================================
+ * Tables for byte-wise and braided CRC-32 calculations, and a table of powers
+ * of x for combining CRC-32s, all made by make_crc_table().
+ */
+#include "crc32.h"
+#endif /* DYNAMIC_CRC_TABLE */
+
+/* ========================================================================
+ * Routines used for CRC calculation. Some are also required for the table
+ * generation above.
+ */
+
+/*
+ Return a(x) multiplied by b(x) modulo p(x), where p(x) is the CRC polynomial,
+ reflected. For speed, this requires that a not be zero.
+ */
+local z_crc_t multmodp(a, b)
+ z_crc_t a;
+ z_crc_t b;
+{
+ z_crc_t m, p;
+
+ m = (z_crc_t)1 << 31;
+ p = 0;
+ for (;;) {
+ if (a & m) {
+ p ^= b;
+ if ((a & (m - 1)) == 0)
+ break;
+ }
+ m >>= 1;
+ b = b & 1 ? (b >> 1) ^ POLY : b >> 1;
+ }
+ return p;
+}
+
+/*
+ Return x^(n * 2^k) modulo p(x). Requires that x2n_table[] has been
+ initialized.
+ */
+local z_crc_t x2nmodp(n, k)
+ z_off64_t n;
+ unsigned k;
+{
+ z_crc_t p;
+
+ p = (z_crc_t)1 << 31; /* x^0 == 1 */
+ while (n) {
+ if (n & 1)
+ p = multmodp(x2n_table[k & 31], p);
+ n >>= 1;
+ k++;
+ }
+ return p;
+}
+
+/* =========================================================================
+ * This function can be used by asm versions of crc32(), and to force the
+ * generation of the CRC tables in a threaded application.
+ */
+const z_crc_t FAR * ZEXPORT get_crc_table()
+{
+#ifdef DYNAMIC_CRC_TABLE
+ once(&made, make_crc_table);
+#endif /* DYNAMIC_CRC_TABLE */
+ return (const z_crc_t FAR *)crc_table;
+}
+
+/* =========================================================================
+ * Use ARM machine instructions if available. This will compute the CRC about
+ * ten times faster than the braided calculation. This code does not check for
+ * the presence of the CRC instruction at run time. __ARM_FEATURE_CRC32 will
+ * only be defined if the compilation specifies an ARM processor architecture
+ * that has the instructions. For example, compiling with -march=armv8.1-a or
+ * -march=armv8-a+crc, or -march=native if the compile machine has the crc32
+ * instructions.
+ */
+#ifdef ARMCRC32
+
+/*
+ Constants empirically determined to maximize speed. These values are from
+ measurements on a Cortex-A57. Your mileage may vary.
+ */
+#define Z_BATCH 3990 /* number of words in a batch */
+#define Z_BATCH_ZEROS 0xa10d3d0c /* computed from Z_BATCH = 3990 */
+#define Z_BATCH_MIN 800 /* fewest words in a final batch */
+
+unsigned long ZEXPORT crc32_z(crc, buf, len)
+ unsigned long crc;
+ const unsigned char FAR *buf;
+ z_size_t len;
+{
+ z_crc_t val;
+ z_word_t crc1, crc2;
+ const z_word_t *word;
+ z_word_t val0, val1, val2;
+ z_size_t last, last2, i;
+ z_size_t num;
+
+ /* Return initial CRC, if requested. */
+ if (buf == Z_NULL) return 0;
+
+#ifdef DYNAMIC_CRC_TABLE
+ once(&made, make_crc_table);
+#endif /* DYNAMIC_CRC_TABLE */
+
+ /* Pre-condition the CRC */
+ crc ^= 0xffffffff;
+
+ /* Compute the CRC up to a word boundary. */
+ while (len && ((z_size_t)buf & 7) != 0) {
+ len--;
+ val = *buf++;
+ __asm__ volatile("crc32b %w0, %w0, %w1" : "+r"(crc) : "r"(val));
+ }
+
+ /* Prepare to compute the CRC on full 64-bit words word[0..num-1]. */
+ word = (z_word_t const *)buf;
+ num = len >> 3;
+ len &= 7;
+
+ /* Do three interleaved CRCs to realize the throughput of one crc32x
+ instruction per cycle. Each CRC is calcuated on Z_BATCH words. The three
+ CRCs are combined into a single CRC after each set of batches. */
+ while (num >= 3 * Z_BATCH) {
+ crc1 = 0;
+ crc2 = 0;
+ for (i = 0; i < Z_BATCH; i++) {
+ val0 = word[i];
+ val1 = word[i + Z_BATCH];
+ val2 = word[i + 2 * Z_BATCH];
+ __asm__ volatile("crc32x %w0, %w0, %x1" : "+r"(crc) : "r"(val0));
+ __asm__ volatile("crc32x %w0, %w0, %x1" : "+r"(crc1) : "r"(val1));
+ __asm__ volatile("crc32x %w0, %w0, %x1" : "+r"(crc2) : "r"(val2));
+ }
+ word += 3 * Z_BATCH;
+ num -= 3 * Z_BATCH;
+ crc = multmodp(Z_BATCH_ZEROS, crc) ^ crc1;
+ crc = multmodp(Z_BATCH_ZEROS, crc) ^ crc2;
+ }
+
+ /* Do one last smaller batch with the remaining words, if there are enough
+ to pay for the combination of CRCs. */
+ last = num / 3;
+ if (last >= Z_BATCH_MIN) {
+ last2 = last << 1;
+ crc1 = 0;
+ crc2 = 0;
+ for (i = 0; i < last; i++) {
+ val0 = word[i];
+ val1 = word[i + last];
+ val2 = word[i + last2];
+ __asm__ volatile("crc32x %w0, %w0, %x1" : "+r"(crc) : "r"(val0));
+ __asm__ volatile("crc32x %w0, %w0, %x1" : "+r"(crc1) : "r"(val1));
+ __asm__ volatile("crc32x %w0, %w0, %x1" : "+r"(crc2) : "r"(val2));
+ }
+ word += 3 * last;
+ num -= 3 * last;
+ val = x2nmodp(last, 6);
+ crc = multmodp(val, crc) ^ crc1;
+ crc = multmodp(val, crc) ^ crc2;
+ }
+
+ /* Compute the CRC on any remaining words. */
+ for (i = 0; i < num; i++) {
+ val0 = word[i];
+ __asm__ volatile("crc32x %w0, %w0, %x1" : "+r"(crc) : "r"(val0));
+ }
+ word += num;
+
+ /* Complete the CRC on any remaining bytes. */
+ buf = (const unsigned char FAR *)word;
+ while (len) {
+ len--;
+ val = *buf++;
+ __asm__ volatile("crc32b %w0, %w0, %w1" : "+r"(crc) : "r"(val));
+ }
+
+ /* Return the CRC, post-conditioned. */
+ return crc ^ 0xffffffff;
+}
+
+#else
+
+#ifdef W
+
+/*
+ Return the CRC of the W bytes in the word_t data, taking the
+ least-significant byte of the word as the first byte of data, without any pre
+ or post conditioning. This is used to combine the CRCs of each braid.
+ */
+local z_crc_t crc_word(data)
+ z_word_t data;
+{
+ int k;
+ for (k = 0; k < W; k++)
+ data = (data >> 8) ^ crc_table[data & 0xff];
+ return (z_crc_t)data;
+}
+
+local z_word_t crc_word_big(data)
+ z_word_t data;
+{
+ int k;
+ for (k = 0; k < W; k++)
+ data = (data << 8) ^
+ crc_big_table[(data >> ((W - 1) << 3)) & 0xff];
+ return data;
+}
+
+#endif
/* ========================================================================= */
-uLong crc32(crc, buf, len)
- uLong crc;
- Bytef *buf;
- uInt len;
+unsigned long ZEXPORT crc32_z(crc, buf, len)
+ unsigned long crc;
+ const unsigned char FAR *buf;
+ z_size_t len;
{
- if (buf == Z_NULL) return 0L;
+ /* Return initial CRC, if requested. */
+ if (buf == Z_NULL) return 0;
+
#ifdef DYNAMIC_CRC_TABLE
- if (crc_table_empty)
- make_crc_table();
+ once(&made, make_crc_table);
+#endif /* DYNAMIC_CRC_TABLE */
+
+ /* Pre-condition the CRC */
+ crc ^= 0xffffffff;
+
+#ifdef W
+
+ /* If provided enough bytes, do a braided CRC calculation. */
+ if (len >= N * W + W - 1) {
+ z_size_t blks;
+ z_word_t const *words;
+ unsigned endian;
+ int k;
+
+ /* Compute the CRC up to a z_word_t boundary. */
+ while (len && ((z_size_t)buf & (W - 1)) != 0) {
+ len--;
+ crc = (crc >> 8) ^ crc_table[(crc ^ *buf++) & 0xff];
+ }
+
+ /* Compute the CRC on as many N z_word_t blocks as are available. */
+ blks = len / (N * W);
+ len -= blks * N * W;
+ words = (z_word_t const *)buf;
+
+ /* Do endian check at execution time instead of compile time, since ARM
+ processors can change the endianess at execution time. If the
+ compiler knows what the endianess will be, it can optimize out the
+ check and the unused branch. */
+ endian = 1;
+ if (*(unsigned char *)&endian) {
+ /* Little endian. */
+
+ z_crc_t crc0;
+ z_word_t word0;
+#if N > 1
+ z_crc_t crc1;
+ z_word_t word1;
+#if N > 2
+ z_crc_t crc2;
+ z_word_t word2;
+#if N > 3
+ z_crc_t crc3;
+ z_word_t word3;
+#if N > 4
+ z_crc_t crc4;
+ z_word_t word4;
+#if N > 5
+ z_crc_t crc5;
+ z_word_t word5;
#endif
- crc = crc ^ 0xffffffffL;
- while (len >= 8)
- {
- DO8(buf);
- len -= 8;
+#endif
+#endif
+#endif
+#endif
+
+ /* Initialize the CRC for each braid. */
+ crc0 = crc;
+#if N > 1
+ crc1 = 0;
+#if N > 2
+ crc2 = 0;
+#if N > 3
+ crc3 = 0;
+#if N > 4
+ crc4 = 0;
+#if N > 5
+ crc5 = 0;
+#endif
+#endif
+#endif
+#endif
+#endif
+
+ /*
+ Process the first blks-1 blocks, computing the CRCs on each braid
+ independently.
+ */
+ while (--blks) {
+ /* Load the word for each braid into registers. */
+ word0 = crc0 ^ words[0];
+#if N > 1
+ word1 = crc1 ^ words[1];
+#if N > 2
+ word2 = crc2 ^ words[2];
+#if N > 3
+ word3 = crc3 ^ words[3];
+#if N > 4
+ word4 = crc4 ^ words[4];
+#if N > 5
+ word5 = crc5 ^ words[5];
+#endif
+#endif
+#endif
+#endif
+#endif
+ words += N;
+
+ /* Compute and update the CRC for each word. The loop should
+ get unrolled. */
+ crc0 = crc_braid_table[0][word0 & 0xff];
+#if N > 1
+ crc1 = crc_braid_table[0][word1 & 0xff];
+#if N > 2
+ crc2 = crc_braid_table[0][word2 & 0xff];
+#if N > 3
+ crc3 = crc_braid_table[0][word3 & 0xff];
+#if N > 4
+ crc4 = crc_braid_table[0][word4 & 0xff];
+#if N > 5
+ crc5 = crc_braid_table[0][word5 & 0xff];
+#endif
+#endif
+#endif
+#endif
+#endif
+ for (k = 1; k < W; k++) {
+ crc0 ^= crc_braid_table[k][(word0 >> (k << 3)) & 0xff];
+#if N > 1
+ crc1 ^= crc_braid_table[k][(word1 >> (k << 3)) & 0xff];
+#if N > 2
+ crc2 ^= crc_braid_table[k][(word2 >> (k << 3)) & 0xff];
+#if N > 3
+ crc3 ^= crc_braid_table[k][(word3 >> (k << 3)) & 0xff];
+#if N > 4
+ crc4 ^= crc_braid_table[k][(word4 >> (k << 3)) & 0xff];
+#if N > 5
+ crc5 ^= crc_braid_table[k][(word5 >> (k << 3)) & 0xff];
+#endif
+#endif
+#endif
+#endif
+#endif
+ }
+ }
+
+ /*
+ Process the last block, combining the CRCs of the N braids at the
+ same time.
+ */
+ crc = crc_word(crc0 ^ words[0]);
+#if N > 1
+ crc = crc_word(crc1 ^ words[1] ^ crc);
+#if N > 2
+ crc = crc_word(crc2 ^ words[2] ^ crc);
+#if N > 3
+ crc = crc_word(crc3 ^ words[3] ^ crc);
+#if N > 4
+ crc = crc_word(crc4 ^ words[4] ^ crc);
+#if N > 5
+ crc = crc_word(crc5 ^ words[5] ^ crc);
+#endif
+#endif
+#endif
+#endif
+#endif
+ words += N;
+ }
+ else {
+ /* Big endian. */
+
+ z_word_t crc0, word0, comb;
+#if N > 1
+ z_word_t crc1, word1;
+#if N > 2
+ z_word_t crc2, word2;
+#if N > 3
+ z_word_t crc3, word3;
+#if N > 4
+ z_word_t crc4, word4;
+#if N > 5
+ z_word_t crc5, word5;
+#endif
+#endif
+#endif
+#endif
+#endif
+
+ /* Initialize the CRC for each braid. */
+ crc0 = byte_swap(crc);
+#if N > 1
+ crc1 = 0;
+#if N > 2
+ crc2 = 0;
+#if N > 3
+ crc3 = 0;
+#if N > 4
+ crc4 = 0;
+#if N > 5
+ crc5 = 0;
+#endif
+#endif
+#endif
+#endif
+#endif
+
+ /*
+ Process the first blks-1 blocks, computing the CRCs on each braid
+ independently.
+ */
+ while (--blks) {
+ /* Load the word for each braid into registers. */
+ word0 = crc0 ^ words[0];
+#if N > 1
+ word1 = crc1 ^ words[1];
+#if N > 2
+ word2 = crc2 ^ words[2];
+#if N > 3
+ word3 = crc3 ^ words[3];
+#if N > 4
+ word4 = crc4 ^ words[4];
+#if N > 5
+ word5 = crc5 ^ words[5];
+#endif
+#endif
+#endif
+#endif
+#endif
+ words += N;
+
+ /* Compute and update the CRC for each word. The loop should
+ get unrolled. */
+ crc0 = crc_braid_big_table[0][word0 & 0xff];
+#if N > 1
+ crc1 = crc_braid_big_table[0][word1 & 0xff];
+#if N > 2
+ crc2 = crc_braid_big_table[0][word2 & 0xff];
+#if N > 3
+ crc3 = crc_braid_big_table[0][word3 & 0xff];
+#if N > 4
+ crc4 = crc_braid_big_table[0][word4 & 0xff];
+#if N > 5
+ crc5 = crc_braid_big_table[0][word5 & 0xff];
+#endif
+#endif
+#endif
+#endif
+#endif
+ for (k = 1; k < W; k++) {
+ crc0 ^= crc_braid_big_table[k][(word0 >> (k << 3)) & 0xff];
+#if N > 1
+ crc1 ^= crc_braid_big_table[k][(word1 >> (k << 3)) & 0xff];
+#if N > 2
+ crc2 ^= crc_braid_big_table[k][(word2 >> (k << 3)) & 0xff];
+#if N > 3
+ crc3 ^= crc_braid_big_table[k][(word3 >> (k << 3)) & 0xff];
+#if N > 4
+ crc4 ^= crc_braid_big_table[k][(word4 >> (k << 3)) & 0xff];
+#if N > 5
+ crc5 ^= crc_braid_big_table[k][(word5 >> (k << 3)) & 0xff];
+#endif
+#endif
+#endif
+#endif
+#endif
+ }
+ }
+
+ /*
+ Process the last block, combining the CRCs of the N braids at the
+ same time.
+ */
+ comb = crc_word_big(crc0 ^ words[0]);
+#if N > 1
+ comb = crc_word_big(crc1 ^ words[1] ^ comb);
+#if N > 2
+ comb = crc_word_big(crc2 ^ words[2] ^ comb);
+#if N > 3
+ comb = crc_word_big(crc3 ^ words[3] ^ comb);
+#if N > 4
+ comb = crc_word_big(crc4 ^ words[4] ^ comb);
+#if N > 5
+ comb = crc_word_big(crc5 ^ words[5] ^ comb);
+#endif
+#endif
+#endif
+#endif
+#endif
+ words += N;
+ crc = byte_swap(comb);
+ }
+
+ /*
+ Update the pointer to the remaining bytes to process.
+ */
+ buf = (unsigned char const *)words;
}
- if (len) do {
- DO1(buf);
- } while (--len);
- return crc ^ 0xffffffffL;
+
+#endif /* W */
+
+ /* Complete the computation of the CRC on any remaining bytes. */
+ while (len >= 8) {
+ len -= 8;
+ crc = (crc >> 8) ^ crc_table[(crc ^ *buf++) & 0xff];
+ crc = (crc >> 8) ^ crc_table[(crc ^ *buf++) & 0xff];
+ crc = (crc >> 8) ^ crc_table[(crc ^ *buf++) & 0xff];
+ crc = (crc >> 8) ^ crc_table[(crc ^ *buf++) & 0xff];
+ crc = (crc >> 8) ^ crc_table[(crc ^ *buf++) & 0xff];
+ crc = (crc >> 8) ^ crc_table[(crc ^ *buf++) & 0xff];
+ crc = (crc >> 8) ^ crc_table[(crc ^ *buf++) & 0xff];
+ crc = (crc >> 8) ^ crc_table[(crc ^ *buf++) & 0xff];
+ }
+ while (len) {
+ len--;
+ crc = (crc >> 8) ^ crc_table[(crc ^ *buf++) & 0xff];
+ }
+
+ /* Return the CRC, post-conditioned. */
+ return crc ^ 0xffffffff;
+}
+
+#endif
+
+/* ========================================================================= */
+unsigned long ZEXPORT crc32(crc, buf, len)
+ unsigned long crc;
+ const unsigned char FAR *buf;
+ uInt len;
+{
+ return crc32_z(crc, buf, len);
+}
+
+/* ========================================================================= */
+uLong ZEXPORT crc32_combine64(crc1, crc2, len2)
+ uLong crc1;
+ uLong crc2;
+ z_off64_t len2;
+{
+#ifdef DYNAMIC_CRC_TABLE
+ once(&made, make_crc_table);
+#endif /* DYNAMIC_CRC_TABLE */
+ return multmodp(x2nmodp(len2, 3), crc1) ^ crc2;
+}
+
+/* ========================================================================= */
+uLong ZEXPORT crc32_combine(crc1, crc2, len2)
+ uLong crc1;
+ uLong crc2;
+ z_off_t len2;
+{
+ return crc32_combine64(crc1, crc2, len2);
+}
+
+/* ========================================================================= */
+uLong ZEXPORT crc32_combine_gen64(len2)
+ z_off64_t len2;
+{
+#ifdef DYNAMIC_CRC_TABLE
+ once(&made, make_crc_table);
+#endif /* DYNAMIC_CRC_TABLE */
+ return x2nmodp(len2, 3);
+}
+
+/* ========================================================================= */
+uLong ZEXPORT crc32_combine_gen(len2)
+ z_off_t len2;
+{
+ return crc32_combine_gen64(len2);
+}
+
+/* ========================================================================= */
+uLong crc32_combine_op(crc1, crc2, op)
+ uLong crc1;
+ uLong crc2;
+ uLong op;
+{
+ return multmodp(op, crc1) ^ crc2;
}
projects / zlib.git / blobdiff