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Patch from Rob Sullivan to consolidate crc32 table generation.

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This commit is contained in:
Rob Landley
2006-04-10 17:07:15 +00:00
parent 998f449375
commit c57ec37959
6 changed files with 65 additions and 71 deletions
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35
archival/gzip.c
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@@ -293,6 +293,7 @@ static int ofd; /* output file descriptor */
static unsigned insize; /* valid bytes in inbuf */
static unsigned outcnt; /* bytes in output buffer */
static uint32_t *crc_32_tab;
/* Output a 16 bit value, lsb first */
static void put_short(ush w)
@@ -344,32 +345,13 @@ static void write_buf(int fd, void *buf, unsigned cnt)
* pointer, then initialize the crc shift register contents instead.
* Return the current crc in either case.
*/
static ulg updcrc(uch * s, unsigned n)
static uint32_t updcrc(uch * s, unsigned n)
{
static ulg crc = (ulg) 0xffffffffL; /* shift register contents */
register ulg c; /* temporary variable */
static unsigned long crc_32_tab[256];
if (crc_32_tab[1] == 0x00000000L) {
unsigned long csr; /* crc shift register */
const unsigned long e = 0xedb88320L; /* polynomial exclusive-or pattern */
int i; /* counter for all possible eight bit values */
int k; /* byte being shifted into crc apparatus */
/* Compute table of CRC's. */
for (i = 1; i < 256; i++) {
csr = i;
/* The idea to initialize the register with the byte instead of
* zero was stolen from Haruhiko Okumura's ar002
*/
for (k = 8; k; k--)
csr = csr & 1 ? (csr >> 1) ^ e : csr >> 1;
crc_32_tab[i] = csr;
}
}
static uint32_t crc = ~0; /* shift register contents */
uint32_t c; /* temporary variable */
if (s == NULL) {
c = 0xffffffffL;
c = ~0;
} else {
c = crc;
if (n)
@@ -378,7 +360,7 @@ static ulg updcrc(uch * s, unsigned n)
} while (--n);
}
crc = c;
return c ^ 0xffffffffL; /* (instead of ~c for 64-bit machines) */
return ~c;
}
/* bits.c -- output variable-length bit strings
@@ -1223,6 +1205,9 @@ int gzip_main(int argc, char **argv)
ALLOC(uch, window, 2L * WSIZE);
ALLOC(ush, tab_prefix, 1L << BITS);
/* Initialise the CRC32 table */
crc_32_tab = bb_crc32_filltable(0);
clear_bufs();
part_nb = 0;
@@ -2416,7 +2401,7 @@ static void set_file_type(void)
*/
static ulg crc; /* crc on uncompressed file data */
static uint32_t crc; /* crc on uncompressed file data */
static long header_bytes; /* number of bytes in gzip header */
static void put_long(ulg n)