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Diffstat (limited to '')
| -rw-r--r-- | modules/zlib/src/crc32.c | 1125 |
1 files changed, 1125 insertions, 0 deletions
diff --git a/modules/zlib/src/crc32.c b/modules/zlib/src/crc32.c new file mode 100644 index 0000000000..f8357b083f --- /dev/null +++ b/modules/zlib/src/crc32.c @@ -0,0 +1,1125 @@ +/* crc32.c -- compute the CRC-32 of a data stream + * 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. + */ + +/* @(#) $Id$ */ + +/* + 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(). + + 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 + +/* If available, use the ARM processor CRC32 instruction. */ +#if defined(__aarch64__) && defined(__ARM_FEATURE_CRC32) && W == 8 +# define ARMCRC32 +#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 defined(W) && (!defined(ARMCRC32) || defined(DYNAMIC_CRC_TABLE)) + local z_word_t byte_swap OF((z_word_t word)); +#endif + +#if defined(W) && !defined(ARMCRC32) + local z_crc_t crc_word OF((z_word_t data)); + local z_word_t crc_word_big OF((z_word_t data)); +#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 + +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. + */ + +/* 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); +{ + 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 /* 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 + +#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 = (~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 calculated 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 + +/* ========================================================================= */ +unsigned long ZEXPORT crc32_z(crc, buf, len) + unsigned long crc; + const unsigned char FAR *buf; + z_size_t len; +{ + /* 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 = (~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 +#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; + } + +#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 & 0xffffffff); +} + +/* ========================================================================= */ +uLong ZEXPORT crc32_combine(crc1, crc2, len2) + uLong crc1; + uLong crc2; + z_off_t len2; +{ + return crc32_combine64(crc1, crc2, (z_off64_t)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((z_off64_t)len2); +} + +/* ========================================================================= */ +uLong ZEXPORT crc32_combine_op(crc1, crc2, op) + uLong crc1; + uLong crc2; + uLong op; +{ + return multmodp(op, crc1) ^ (crc2 & 0xffffffff); +} |