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Simplify CRC table generation

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This commit is contained in:
Glenn L McGrath 2001-12-05 13:08:03 +00:00
parent aad44fb37a
commit ef03dbcd4d
3 changed files with 15 additions and 33 deletions
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16
archival/libunarchive/decompress_unzip.c
View File

@ -123,22 +123,16 @@ static void abort_gzip(void)
static void make_crc_table(void)
{
unsigned long table_entry; /* crc shift register */
unsigned long poly = 0; /* polynomial exclusive-or pattern */
int i; /* counter for all possible eight bit values */
int k; /* byte being shifted into crc apparatus */
/* terms of polynomial defining this crc (except x^32): */
static int p[] = {0,1,2,4,5,7,8,10,11,12,16,22,23,26};
const unsigned long poly = 0xedb88320; /* polynomial exclusive-or pattern */
unsigned short i; /* counter for all possible eight bit values */
crc_table = (unsigned long *) malloc(256 * sizeof(unsigned long));
/* Make exclusive-or pattern from polynomial (0xedb88320) */
for (i = 0; i < sizeof(p)/sizeof(int); i++)
poly |= 1L << (31 - p[i]);
/* Compute and print table of CRC's, five per line */
for (i = 0; i < 256; i++) {
unsigned long table_entry; /* crc shift register */
char k; /* byte being shifted into crc apparatus */
table_entry = i;
/* The idea to initialize the register with the byte instead of
* zero was stolen from Haruhiko Okumura's ar002

16
archival/libunarchive/unzip.c
View File

@ -123,22 +123,16 @@ static void abort_gzip(void)
static void make_crc_table(void)
{
unsigned long table_entry; /* crc shift register */
unsigned long poly = 0; /* polynomial exclusive-or pattern */
int i; /* counter for all possible eight bit values */
int k; /* byte being shifted into crc apparatus */
/* terms of polynomial defining this crc (except x^32): */
static int p[] = {0,1,2,4,5,7,8,10,11,12,16,22,23,26};
const unsigned long poly = 0xedb88320; /* polynomial exclusive-or pattern */
unsigned short i; /* counter for all possible eight bit values */
crc_table = (unsigned long *) malloc(256 * sizeof(unsigned long));
/* Make exclusive-or pattern from polynomial (0xedb88320) */
for (i = 0; i < sizeof(p)/sizeof(int); i++)
poly |= 1L << (31 - p[i]);
/* Compute and print table of CRC's, five per line */
for (i = 0; i < 256; i++) {
unsigned long table_entry; /* crc shift register */
char k; /* byte being shifted into crc apparatus */
table_entry = i;
/* The idea to initialize the register with the byte instead of
* zero was stolen from Haruhiko Okumura's ar002

16
libbb/unzip.c
View File

@ -123,22 +123,16 @@ static void abort_gzip(void)
static void make_crc_table(void)
{
unsigned long table_entry; /* crc shift register */
unsigned long poly = 0; /* polynomial exclusive-or pattern */
int i; /* counter for all possible eight bit values */
int k; /* byte being shifted into crc apparatus */
/* terms of polynomial defining this crc (except x^32): */
static int p[] = {0,1,2,4,5,7,8,10,11,12,16,22,23,26};
const unsigned long poly = 0xedb88320; /* polynomial exclusive-or pattern */
unsigned short i; /* counter for all possible eight bit values */
crc_table = (unsigned long *) malloc(256 * sizeof(unsigned long));
/* Make exclusive-or pattern from polynomial (0xedb88320) */
for (i = 0; i < sizeof(p)/sizeof(int); i++)
poly |= 1L << (31 - p[i]);
/* Compute and print table of CRC's, five per line */
for (i = 0; i < 256; i++) {
unsigned long table_entry; /* crc shift register */
char k; /* byte being shifted into crc apparatus */
table_entry = i;
/* The idea to initialize the register with the byte instead of
* zero was stolen from Haruhiko Okumura's ar002