mchapman/zlib
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

zlib 0.93

Browse Source
This commit is contained in:
Mark Adler
2011-09-09 23:08:28 -07:00
parent bdde4e09d2
commit 6b834a58bd
16 changed files with 253 additions and 203 deletions
Download Patch File Download Diff File Expand all files Collapse all files

69
crc32.c
View File

@@ -7,57 +7,35 @@
#include "zlib.h"
extern uLong crc_table[]; /* crc table, defined below */
#define DO1(buf) crc = crc_table[((int)crc ^ (*buf++)) & 0xff] ^ (crc >> 8);
#define DO2(buf) DO1(buf); DO1(buf);
#define DO4(buf) DO2(buf); DO2(buf);
#define DO8(buf) DO4(buf); DO4(buf);
/* ========================================================================= */
uLong crc32(crc, buf, len)
uLong crc;
Byte *buf;
uInt len;
{
if (buf == Z_NULL) return 0L;
crc = crc ^ 0xffffffffL;
while (len >= 8)
{
DO8(buf);
len -= 8;
}
if (len) do {
DO1(buf);
} while (--len);
return crc ^ 0xffffffffL;
}
#define local static
#ifdef DYNAMIC_CRC_TABLE
/* =========================================================================
* Make the crc table. This function is needed only if you want to compute
* the table dynamically.
*/
#ifdef DYNAMIC_CRC_TABLE
local int crc_table_empty = 1;
local uLong crc_table[256];
local void make_crc_table()
{
uLong c;
int n, k;
for (n = 0; n < 256; n++)
for (n = 0; n < 256; n++)
{
c = (uLong)n;
for (k = 0; k &lt; 8; k++)
for (k = 0; k < 8; k++)
c = c & 1 ? 0xedb88320L ^ (c >> 1) : c >> 1;
crc_table[n] = c;
}
crc_table_empty = 0;
}
#endif
#else
/* ========================================================================
* Table of CRC-32's of all single-byte values (made by make_crc_table)
*/
uLong crc_table[] = {
local uLong crc_table[] = {
0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L,
0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L,
0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L,
@@ -111,3 +89,32 @@ uLong crc_table[] = {
0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL,
0x2d02ef8dL
};
#endif
#define DO1(buf) crc = crc_table[((int)crc ^ (*buf++)) & 0xff] ^ (crc >> 8);
#define DO2(buf) DO1(buf); DO1(buf);
#define DO4(buf) DO2(buf); DO2(buf);
#define DO8(buf) DO4(buf); DO4(buf);
/* ========================================================================= */
uLong crc32(crc, buf, len)
uLong crc;
Byte *buf;
uInt len;
{
if (buf == Z_NULL) return 0L;
#ifdef DYNAMIC_CRC_TABLE
if (crc_table_empty)
make_crc_table();
#endif
crc = crc ^ 0xffffffffL;
while (len >= 8)
{
DO8(buf);
len -= 8;
}
if (len) do {
DO1(buf);
} while (--len);
return crc ^ 0xffffffffL;
}