/* crc32.c -- compute the CRC-32 of a data stream
- * Copyright (C) 1995-2006, 2010, 2011, 2012, 2016, 2018 Mark Adler
+ * Copyright (C) 1995-2022 Mark Adler
* For conditions of distribution and use, see copyright notice in zlib.h
*
- * Thanks to Rodney Brown <rbrown64@csc.com.au> 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.
*/
/* @(#) $Id$ */
/*
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
# 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
+/* 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
-#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
+
+/*
+ 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
-# define TBLS 1
-#endif /* BYFOUR */
+# 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 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));
+/* 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));
-/* ========================================================================= */
-local z_crc_t gf2_matrix_times(mat, vec)
- const z_crc_t *mat;
- z_crc_t vec;
+/* 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;
{
- z_crc_t sum;
-
- sum = 0;
- while (vec) {
- if (vec & 1)
- sum ^= *mat;
- vec >>= 1;
- mat++;
- }
- return sum;
+# 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 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;
+/*
+ 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);
{
- int n;
+ 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 */
- for (n = 0; n < GF2_DIM; n++)
- square[n] = gf2_matrix_times(mat, mat[n]);
+/* 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
+ 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,
+ 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
+ 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): */
- 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) {
- 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;
- }
+ 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
+ }
-#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 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
- /* 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]);
-
- /* mark tables as complete, in case someone else is waiting */
- crc_table_empty = 0;
- }
- else { /* not first */
- /* wait for the other guy to finish (not efficient, but rare) */
- while (crc_table_empty)
- ;
- }
#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;
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 * 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()
+ * 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
- if (crc_table_empty)
- make_crc_table();
+ once(&made, make_crc_table);
#endif /* DYNAMIC_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
+/* =========================================================================
+ * 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;
{
- if (buf == Z_NULL) return 0UL;
+ 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
- if (crc_table_empty)
- make_crc_table();
+ once(&made, 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;
- endian = 1;
- if (*((unsigned char *)(&endian)))
- return crc32_little(crc, buf, len);
- else
- return crc32_big(crc, buf, len);
+ /* 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));
}
-#endif /* BYFOUR */
- crc = crc ^ 0xffffffffUL;
- while (len >= 8) {
- DO8;
- len -= 8;
+
+ /* 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;
}
- if (len) do {
- DO1;
- } while (--len);
- return crc ^ 0xffffffffUL;
-}
-/* ========================================================================= */
-unsigned long ZEXPORT crc32(crc, buf, len)
- unsigned long crc;
- const unsigned char FAR *buf;
- uInt len;
-{
- return crc32_z(crc, buf, len);
+ /* 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;
}
-#ifdef BYFOUR
+#else
+
+#ifdef W
/*
- 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.
+ 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;
+}
-/* ========================================================================= */
-#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
+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
/* ========================================================================= */
-local unsigned long crc32_little(crc, buf, len)
+unsigned long ZEXPORT crc32_z(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;
+ /* Return initial CRC, if requested. */
+ if (buf == Z_NULL) return 0;
- c = (z_crc_t)crc;
- c = ~c;
- while (len && ((z_size_t)buf & 3)) {
- c = crc_table[0][(c ^ *buf++) & 0xff] ^ (c >> 8);
- len--;
+#ifdef DYNAMIC_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
+#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;
}
- 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
+#endif
/* ========================================================================= */
-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();
+ once(&made, 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;
}
/* ========================================================================= */
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();
+ once(&made, 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;
}
projects / zlib.git / blobdiff