X-Git-Url: https://git.lizzy.rs/?a=blobdiff_plain;f=crc32.c;h=f41dc6d2263e9af623cd549b3d543a86f13d17c5;hb=f8719f5ae5acdc31d3794ddfea8ac963359de41e;hp=2d213b31f9476c40829c11b26445a5834d9f46f3;hpb=41d86c73b21191a3fa9ea5f476fc9f1fc5e4f8b3;p=zlib.git diff --git a/crc32.c b/crc32.c index 2d213b3..f41dc6d 100644 --- a/crc32.c +++ b/crc32.c @@ -2,11 +2,9 @@ * Copyright (C) 1995-2006, 2010, 2011, 2012, 2016, 2018 Mark Adler * For conditions of distribution and use, see copyright notice in zlib.h * - * Thanks to Rodney Brown for his contribution of faster - * CRC methods: exclusive-oring 32 bits of data at a time, and pre-computing - * tables for updating the shift register in one step with three exclusive-ors - * instead of four steps with four exclusive-ors. This results in about a - * factor of two increase in speed on a Power PC G4 (PPC7455) using gcc -O3. + * 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. */ /* @(#) $Id$ */ @@ -14,13 +12,12 @@ /* 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 + 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(). - DYNAMIC_CRC_TABLE and 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. + 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 @@ -30,161 +27,164 @@ # endif /* !DYNAMIC_CRC_TABLE */ #endif /* MAKECRCH */ -#include "zutil.h" /* for STDC and FAR definitions */ +#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. + */ -/* Definitions for doing the crc four data bytes at a time. */ -#if !defined(NOBYFOUR) && defined(Z_U4) -# define BYFOUR -#endif -#ifdef BYFOUR - local unsigned long crc32_little OF((unsigned long, - const unsigned char FAR *, z_size_t)); - local unsigned long crc32_big OF((unsigned long, - const unsigned char FAR *, z_size_t)); -# define TBLS 8 +/* Define N */ +#ifdef Z_TESTN +# define N Z_TESTN #else -# define TBLS 1 -#endif /* BYFOUR */ +# define N 5 +#endif +#if N < 1 || N > 6 +# error N must be in 1..6 +#endif -/* Local functions for crc concatenation */ -#define GF2_DIM 32 /* dimension of GF(2) vectors (length of CRC) */ -local z_crc_t gf2_matrix_times OF((const z_crc_t *mat, z_crc_t vec)); -local uLong crc32_combine_ OF((uLong crc1, uLong crc2, z_off64_t len2)); -local void crc32_combine_gen_ OF((z_crc_t *op, z_off64_t len2)); +/* + 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. + */ -/* ========================================================================= */ -local z_crc_t gf2_matrix_times(mat, vec) - const z_crc_t *mat; - z_crc_t vec; -{ - z_crc_t sum; - - sum = 0; - while (vec) { - if (vec & 1) - sum ^= *mat; - vec >>= 1; - mat++; - } - return sum; -} +/* + 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)); +#ifdef W + local z_word_t byte_swap OF((z_word_t word)); + local z_crc_t crc_word OF((z_word_t data)); + local z_word_t crc_word_big OF((z_word_t data)); +#endif /* W */ +/* CRC polynomial. */ +#define POLY 0xedb88320 /* p(x) reflected, with x^32 implied */ #ifdef DYNAMIC_CRC_TABLE local volatile int crc_table_empty = 1; -local z_crc_t FAR crc_table[TBLS][256]; -local z_crc_t FAR crc_comb[GF2_DIM][GF2_DIM]; +local z_crc_t FAR crc_table[256]; +local z_crc_t FAR x2n_table[32]; local void make_crc_table OF((void)); -local void gf2_matrix_square OF((z_crc_t *square, const z_crc_t *mat)); +#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 */ -/* ========================================================================= */ -local void gf2_matrix_square(square, mat) - z_crc_t *square; - const z_crc_t *mat; -{ - int n; - - for (n = 0; n < GF2_DIM; n++) - square[n] = gf2_matrix_times(mat, mat[n]); -} - /* 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 + 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 + 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+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 + 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 first 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. The remaining tables - allow for word-at-a-time CRC calculation for both big-endian and little- - endian machines, where a word is four bytes. -*/ + 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() { - z_crc_t c; - int n, k; - z_crc_t poly; /* polynomial exclusive-or pattern */ - /* terms of polynomial defining this crc (except x^32): */ + z_crc_t p; static volatile int first = 1; /* flag to limit concurrent making */ - static const unsigned char p[] = {0,1,2,4,5,7,8,10,11,12,16,22,23,26}; /* See if another task is already doing this (not thread-safe, but better than nothing -- significantly reduces duration of vulnerability in case the advice about DYNAMIC_CRC_TABLE is ignored) */ if (first) { + unsigned i, j, n; first = 0; - /* make exclusive-or pattern from polynomial (0xedb88320UL) */ - poly = 0; - for (n = 0; n < (int)(sizeof(p)/sizeof(unsigned char)); n++) - poly |= (z_crc_t)1 << (31 - p[n]); - - /* generate a crc for every 8-bit value */ - for (n = 0; n < 256; n++) { - c = (z_crc_t)n; - for (k = 0; k < 8; k++) - c = c & 1 ? poly ^ (c >> 1) : c >> 1; - crc_table[0][n] = c; - } - -#ifdef BYFOUR - /* generate crc for each value followed by one, two, and three zeros, - and then the byte reversal of those as well as the first table */ - for (n = 0; n < 256; n++) { - c = crc_table[0][n]; - crc_table[4][n] = ZSWAP32(c); - for (k = 1; k < 4; k++) { - c = crc_table[0][c & 0xff] ^ (c >> 8); - crc_table[k][n] = c; - crc_table[k + 4][n] = ZSWAP32(c); - } - } -#endif /* BYFOUR */ - - /* generate zero operators table for crc32_combine() */ - - /* generate the operator to apply a single zero bit to a CRC -- the - first row adds the polynomial if the low bit is a 1, and the - remaining rows shift the CRC right one bit */ - k = GF2_DIM - 3; - crc_comb[k][0] = 0xedb88320UL; /* CRC-32 polynomial */ - z_crc_t row = 1; - for (n = 1; n < GF2_DIM; n++) { - crc_comb[k][n] = row; - row <<= 1; + /* 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 } - /* generate operators that apply 2, 4, and 8 zeros to a CRC, putting - the last one, the operator for one zero byte, at the 0 position */ - gf2_matrix_square(crc_comb[k + 1], crc_comb[k]); - gf2_matrix_square(crc_comb[k + 2], crc_comb[k + 1]); - gf2_matrix_square(crc_comb[0], crc_comb[k + 2]); - - /* generate operators for applying 2^n zero bytes to a CRC, filling out - the remainder of the table -- the operators repeat after GF2_DIM - values of n, so the table only needs GF2_DIM entries, regardless of - the size of the length being processed */ - for (n = 1; n < k; n++) - gf2_matrix_square(crc_comb[n], crc_comb[n - 1]); + /* 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 /* mark tables as complete, in case someone else is waiting */ crc_table_empty = 0; @@ -196,42 +196,145 @@ local void make_crc_table() } #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 CRC table to crc32.h */ - fprintf(out, "/* crc32.h -- tables for rapid CRC calculation\n"); - fprintf(out, " * Generated automatically by crc32.c\n */\n\n"); - fprintf(out, "local const z_crc_t FAR "); - fprintf(out, "crc_table[%d][256] =\n{\n {\n", TBLS); - write_table(out, crc_table[0], 256); -# ifdef BYFOUR - fprintf(out, "#ifdef BYFOUR\n"); - for (k = 1; k < 8; k++) { - fprintf(out, " },\n {\n"); - write_table(out, crc_table[k], 256); - } - fprintf(out, "#endif\n"); -# endif /* BYFOUR */ - fprintf(out, " }\n};\n"); - - /* write out zero operator table to crc32.h */ - fprintf(out, "\nlocal const z_crc_t FAR "); - fprintf(out, "crc_comb[%d][%d] =\n{\n {\n", GF2_DIM, GF2_DIM); - write_table(out, crc_comb[0], GF2_DIM); - for (k = 1; k < GF2_DIM; k++) { - fprintf(out, " },\n {\n"); - write_table(out, crc_comb[k], GF2_DIM); + /* 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};\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; @@ -240,26 +343,194 @@ local void write_table(out, table, k) int n; for (n = 0; n < k; n++) - fprintf(out, "%s0x%08lxUL%s", n % 5 ? "" : " ", + fprintf(out, "%s0x%08lx%s", n == 0 || n % 5 ? "" : " ", (unsigned long)(table[n]), - n == k - 1 ? "\n" : (n % 5 == 4 ? ",\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 of CRC-32s of all single-byte values, made by make_crc_table(), - * and tables of zero operator matrices for crc32_combine(). + * 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+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; +} + +#ifdef W + +/* + 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 +} + +/* + 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 /* W */ + /* ========================================================================= * This function can be used by asm versions of crc32() */ @@ -272,169 +543,349 @@ const z_crc_t FAR * ZEXPORT get_crc_table() return (const z_crc_t FAR *)crc_table; } -/* ========================================================================= */ -#define DO1 crc = crc_table[0][((int)crc ^ (*buf++)) & 0xff] ^ (crc >> 8) -#define DO8 DO1; DO1; DO1; DO1; DO1; DO1; DO1; DO1 - /* ========================================================================= */ 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 0UL; + /* Return initial CRC, if requested. */ + if (buf == Z_NULL) return 0; #ifdef DYNAMIC_CRC_TABLE if (crc_table_empty) make_crc_table(); #endif /* DYNAMIC_CRC_TABLE */ -#ifdef BYFOUR - if (sizeof(void *) == sizeof(z_size_t)) { - z_crc_t endian; + /* 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))) - return crc32_little(crc, buf, len); - else - return crc32_big(crc, buf, len); - } -#endif /* BYFOUR */ - crc = crc ^ 0xffffffffUL; - while (len >= 8) { - DO8; - len -= 8; - } - if (len) do { - DO1; - } while (--len); - return crc ^ 0xffffffffUL; -} + 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 -/* ========================================================================= */ -unsigned long ZEXPORT crc32(crc, buf, len) - unsigned long crc; - const unsigned char FAR *buf; - uInt len; -{ - return crc32_z(crc, buf, len); -} + /* 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 -#ifdef BYFOUR + /* + 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 + } + } -/* - This BYFOUR code accesses the passed unsigned char * buffer with a 32-bit - integer pointer type. This violates the strict aliasing rule, where a - compiler can assume, for optimization purposes, that two pointers to - fundamentally different types won't ever point to the same memory. This can - manifest as a problem only if one of the pointers is written to. This code - only reads from those pointers. So long as this code remains isolated in - this compilation unit, there won't be a problem. For this reason, this code - should not be copied and pasted into a compilation unit in which other code - writes to the buffer that is passed to these routines. - */ + /* + 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 -/* ========================================================================= */ -#define DOLIT4 c ^= *buf4++; \ - c = crc_table[3][c & 0xff] ^ crc_table[2][(c >> 8) & 0xff] ^ \ - crc_table[1][(c >> 16) & 0xff] ^ crc_table[0][c >> 24] -#define DOLIT32 DOLIT4; DOLIT4; DOLIT4; DOLIT4; DOLIT4; DOLIT4; DOLIT4; DOLIT4 + /* 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 -/* ========================================================================= */ -local unsigned long crc32_little(crc, buf, len) - unsigned long crc; - const unsigned char FAR *buf; - z_size_t len; -{ - register z_crc_t c; - register const z_crc_t FAR *buf4; + /* + 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 + } + } - c = (z_crc_t)crc; - c = ~c; - while (len && ((z_size_t)buf & 3)) { - c = crc_table[0][(c ^ *buf++) & 0xff] ^ (c >> 8); - len--; + /* + 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; } - buf4 = (const z_crc_t FAR *)(const void FAR *)buf; - while (len >= 32) { - DOLIT32; - len -= 32; +#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 >= 4) { - DOLIT4; - len -= 4; + while (len) { + len--; + crc = (crc >> 8) ^ crc_table[(crc ^ *buf++) & 0xff]; } - buf = (const unsigned char FAR *)buf4; - if (len) do { - c = crc_table[0][(c ^ *buf++) & 0xff] ^ (c >> 8); - } while (--len); - c = ~c; - return (unsigned long)c; + /* Return the CRC, post-conditioned. */ + return crc ^ 0xffffffff; } /* ========================================================================= */ -#define DOBIG4 c ^= *buf4++; \ - c = crc_table[4][c & 0xff] ^ crc_table[5][(c >> 8) & 0xff] ^ \ - crc_table[6][(c >> 16) & 0xff] ^ crc_table[7][c >> 24] -#define DOBIG32 DOBIG4; DOBIG4; DOBIG4; DOBIG4; DOBIG4; DOBIG4; DOBIG4; DOBIG4 - -/* ========================================================================= */ -local unsigned long crc32_big(crc, buf, len) +unsigned long ZEXPORT crc32(crc, buf, len) unsigned long crc; const unsigned char FAR *buf; - z_size_t len; + uInt len; { - register z_crc_t c; - register const z_crc_t FAR *buf4; - - c = ZSWAP32((z_crc_t)crc); - c = ~c; - while (len && ((z_size_t)buf & 3)) { - c = crc_table[4][(c >> 24) ^ *buf++] ^ (c << 8); - len--; - } - - buf4 = (const z_crc_t FAR *)(const void FAR *)buf; - while (len >= 32) { - DOBIG32; - len -= 32; - } - while (len >= 4) { - DOBIG4; - len -= 4; - } - buf = (const unsigned char FAR *)buf4; - - if (len) do { - c = crc_table[4][(c >> 24) ^ *buf++] ^ (c << 8); - } while (--len); - c = ~c; - return (unsigned long)(ZSWAP32(c)); + return crc32_z(crc, buf, len); } -#endif /* BYFOUR */ - /* ========================================================================= */ -local uLong crc32_combine_(crc1, crc2, len2) +uLong ZEXPORT crc32_combine64(crc1, crc2, len2) uLong crc1; uLong crc2; z_off64_t len2; { - int n; - #ifdef DYNAMIC_CRC_TABLE if (crc_table_empty) make_crc_table(); #endif /* DYNAMIC_CRC_TABLE */ - - if (len2 > 0) - /* operator for 2^n zeros repeats every GF2_DIM n values */ - for (n = 0; len2; n = (n + 1) % GF2_DIM, len2 >>= 1) - if (len2 & 1) - crc1 = gf2_matrix_times(crc_comb[n], crc1); - return crc1 ^ crc2; + return multmodp(x2nmodp(len2, 3), crc1) ^ crc2; } /* ========================================================================= */ @@ -443,87 +894,32 @@ uLong ZEXPORT crc32_combine(crc1, crc2, len2) uLong crc2; z_off_t len2; { - return crc32_combine_(crc1, crc2, len2); -} - -uLong ZEXPORT crc32_combine64(crc1, crc2, len2) - uLong crc1; - uLong crc2; - z_off64_t len2; -{ - return crc32_combine_(crc1, crc2, len2); + return crc32_combine64(crc1, crc2, len2); } /* ========================================================================= */ -local void crc32_combine_gen_(op, len2) - z_crc_t *op; +uLong ZEXPORT crc32_combine_gen64(len2) z_off64_t len2; { - z_crc_t row; - int j; - unsigned i; - #ifdef DYNAMIC_CRC_TABLE if (crc_table_empty) make_crc_table(); #endif /* DYNAMIC_CRC_TABLE */ - - /* if len2 is zero or negative, return the identity matrix */ - if (len2 <= 0) { - row = 1; - for (j = 0; j < GF2_DIM; j++) { - op[j] = row; - row <<= 1; - } - return; - } - - /* at least one bit in len2 is set -- find it, and copy the operator - corresponding to that position into op */ - i = 0; - for (;;) { - if (len2 & 1) { - for (j = 0; j < GF2_DIM; j++) - op[j] = crc_comb[i][j]; - break; - } - len2 >>= 1; - i = (i + 1) % GF2_DIM; - } - - /* for each remaining bit set in len2 (if any), multiply op by the operator - corresponding to that position */ - for (;;) { - len2 >>= 1; - i = (i + 1) % GF2_DIM; - if (len2 == 0) - break; - if (len2 & 1) - for (j = 0; j < GF2_DIM; j++) - op[j] = gf2_matrix_times(crc_comb[i], op[j]); - } + return x2nmodp(len2, 3); } /* ========================================================================= */ -void ZEXPORT crc32_combine_gen(op, len2) - z_crc_t *op; +uLong ZEXPORT crc32_combine_gen(len2) z_off_t len2; { - crc32_combine_gen_(op, len2); -} - -void ZEXPORT crc32_combine_gen64(op, len2) - z_crc_t *op; - z_off64_t len2; -{ - crc32_combine_gen_(op, len2); + return crc32_combine_gen64(len2); } /* ========================================================================= */ uLong crc32_combine_op(crc1, crc2, op) uLong crc1; uLong crc2; - const z_crc_t *op; + uLong op; { - return gf2_matrix_times(op, crc1) ^ crc2; + return multmodp(op, crc1) ^ crc2; }