/* crc32.c -- compute the CRC-32 of a data stream
- * Copyright (C) 1995-2003 Mark Adler
+ * Copyright (C) 1995-2006, 2010, 2011 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 about a factor
- * of two increase in speed on a Power PC G4 (PPC7455) using gcc -O3.
+ * 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.
*/
/* @(#) $Id$ */
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.
*/
#ifdef MAKECRCH
/* Definitions for doing the crc four data bytes at a time. */
#ifdef BYFOUR
-# define REV(w) (((w)>>24)+(((w)>>8)&0xff00)+ \
+ typedef u4 crc_table_t;
+# define REV(w) ((((w)>>24)&0xff)+(((w)>>8)&0xff00)+ \
(((w)&0xff00)<<8)+(((w)&0xff)<<24))
local unsigned long crc32_little OF((unsigned long,
const unsigned char FAR *, unsigned));
const unsigned char FAR *, unsigned));
# define TBLS 8
#else
+ typedef unsigned long crc_table_t;
# define TBLS 1
#endif /* BYFOUR */
+/* Local functions for crc concatenation */
+local unsigned long gf2_matrix_times OF((unsigned long *mat,
+ unsigned long vec));
+local void gf2_matrix_square OF((unsigned long *square, unsigned long *mat));
+local uLong crc32_combine_ OF((uLong crc1, uLong crc2, z_off64_t len2));
+
+
#ifdef DYNAMIC_CRC_TABLE
local volatile int crc_table_empty = 1;
-local unsigned long FAR crc_table[TBLS][256];
+local crc_table_t FAR crc_table[TBLS][256];
local void make_crc_table OF((void));
#ifdef MAKECRCH
- local void write_table OF((FILE *, const unsigned long FAR *));
+ local void write_table OF((FILE *, const crc_table_t FAR *));
#endif /* MAKECRCH */
-
/*
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.
*/
local void make_crc_table()
{
- unsigned long c;
+ crc_table_t c;
int n, k;
- unsigned long poly; /* polynomial exclusive-or pattern */
+ crc_table_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};
first = 0;
/* make exclusive-or pattern from polynomial (0xedb88320UL) */
- poly = 0UL;
- for (n = 0; n < sizeof(p)/sizeof(unsigned char); n++)
- poly |= 1UL << (31 - p[n]);
+ poly = 0;
+ for (n = 0; n < (int)(sizeof(p)/sizeof(unsigned char)); n++)
+ poly |= (crc_table_t)1 << (31 - p[n]);
/* generate a crc for every 8-bit value */
for (n = 0; n < 256; n++) {
- c = (unsigned long)n;
+ c = (crc_table_t)n;
for (k = 0; k < 8; k++)
c = c & 1 ? poly ^ (c >> 1) : c >> 1;
crc_table[0][n] = c;
if (out == NULL) return;
fprintf(out, "/* crc32.h -- tables for rapid CRC calculation\n");
fprintf(out, " * Generated automatically by crc32.c\n */\n\n");
- fprintf(out, "local const unsigned long FAR ");
+ fprintf(out, "local const crc_table_t FAR ");
fprintf(out, "crc_table[TBLS][256] =\n{\n {\n");
write_table(out, crc_table[0]);
# ifdef BYFOUR
#ifdef MAKECRCH
local void write_table(out, table)
FILE *out;
- const unsigned long FAR *table;
+ const crc_table_t FAR *table;
{
int n;
for (n = 0; n < 256; n++)
- fprintf(out, "%s0x%08lxUL%s", n % 5 ? "" : " ", table[n],
+ fprintf(out, "%s0x%08lxUL%s", n % 5 ? "" : " ",
+ (unsigned long)(table[n]),
n == 255 ? "\n" : (n % 5 == 4 ? ",\n" : ", "));
}
#endif /* MAKECRCH */
unsigned long ZEXPORT crc32(crc, buf, len)
unsigned long crc;
const unsigned char FAR *buf;
- unsigned len;
+ uInt len;
{
if (buf == Z_NULL) return 0UL;
len--;
}
- buf4 = (const u4 FAR *)buf;
+ buf4 = (const u4 FAR *)(const void FAR *)buf;
while (len >= 32) {
DOLIT32;
len -= 32;
len--;
}
- buf4 = (const u4 FAR *)buf;
+ buf4 = (const u4 FAR *)(const void FAR *)buf;
buf4--;
while (len >= 32) {
DOBIG32;
}
#endif /* BYFOUR */
+
+#define GF2_DIM 32 /* dimension of GF(2) vectors (length of CRC) */
+
+/* ========================================================================= */
+local unsigned long gf2_matrix_times(mat, vec)
+ unsigned long *mat;
+ unsigned long vec;
+{
+ unsigned long sum;
+
+ sum = 0;
+ while (vec) {
+ if (vec & 1)
+ sum ^= *mat;
+ vec >>= 1;
+ mat++;
+ }
+ return sum;
+}
+
+/* ========================================================================= */
+local void gf2_matrix_square(square, mat)
+ unsigned long *square;
+ unsigned long *mat;
+{
+ int n;
+
+ for (n = 0; n < GF2_DIM; n++)
+ square[n] = gf2_matrix_times(mat, mat[n]);
+}
+
+/* ========================================================================= */
+local uLong crc32_combine_(crc1, crc2, len2)
+ uLong crc1;
+ uLong crc2;
+ z_off64_t len2;
+{
+ int n;
+ unsigned long row;
+ unsigned long even[GF2_DIM]; /* even-power-of-two zeros operator */
+ unsigned long odd[GF2_DIM]; /* odd-power-of-two zeros operator */
+
+ /* degenerate case (also disallow negative lengths) */
+ if (len2 <= 0)
+ return crc1;
+
+ /* put operator for one zero bit in odd */
+ odd[0] = 0xedb88320UL; /* CRC-32 polynomial */
+ row = 1;
+ for (n = 1; n < GF2_DIM; n++) {
+ odd[n] = row;
+ row <<= 1;
+ }
+
+ /* put operator for two zero bits in even */
+ gf2_matrix_square(even, odd);
+
+ /* put operator for four zero bits in odd */
+ gf2_matrix_square(odd, even);
+
+ /* apply len2 zeros to crc1 (first square will put the operator for one
+ zero byte, eight zero bits, in even) */
+ do {
+ /* apply zeros operator for this bit of len2 */
+ gf2_matrix_square(even, odd);
+ if (len2 & 1)
+ crc1 = gf2_matrix_times(even, crc1);
+ len2 >>= 1;
+
+ /* if no more bits set, then done */
+ if (len2 == 0)
+ break;
+
+ /* another iteration of the loop with odd and even swapped */
+ gf2_matrix_square(odd, even);
+ if (len2 & 1)
+ crc1 = gf2_matrix_times(odd, crc1);
+ len2 >>= 1;
+
+ /* if no more bits set, then done */
+ } while (len2 != 0);
+
+ /* return combined crc */
+ crc1 ^= crc2;
+ return crc1;
+}
+
+/* ========================================================================= */
+uLong ZEXPORT crc32_combine(crc1, crc2, len2)
+ uLong crc1;
+ 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);
+}
projects / zlib.git / blobdiff