Patch from Rob Sullivan to consolidate crc32 table generation.

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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@ -293,6 +293,7 @@ static int ofd; /* output file descriptor */
static unsigned insize; /* valid bytes in inbuf */ static unsigned insize; /* valid bytes in inbuf */
static unsigned outcnt; /* bytes in output buffer */ static unsigned outcnt; /* bytes in output buffer */
static uint32_t *crc_32_tab;
/* Output a 16 bit value, lsb first */ /* Output a 16 bit value, lsb first */
static void put_short(ush w) 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. * pointer, then initialize the crc shift register contents instead.
* Return the current crc in either case. * 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 */ static uint32_t crc = ~0; /* shift register contents */
register ulg c; /* temporary variable */ uint32_t 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;
}
}
if (s == NULL) { if (s == NULL) {
c = 0xffffffffL; c = ~0;
} else { } else {
c = crc; c = crc;
if (n) if (n)
@ -378,7 +360,7 @@ static ulg updcrc(uch * s, unsigned n)
} while (--n); } while (--n);
} }
crc = c; crc = c;
return c ^ 0xffffffffL; /* (instead of ~c for 64-bit machines) */ return ~c;
} }
/* bits.c -- output variable-length bit strings /* bits.c -- output variable-length bit strings
@ -1223,6 +1205,9 @@ int gzip_main(int argc, char **argv)
ALLOC(uch, window, 2L * WSIZE); ALLOC(uch, window, 2L * WSIZE);
ALLOC(ush, tab_prefix, 1L << BITS); ALLOC(ush, tab_prefix, 1L << BITS);
/* Initialise the CRC32 table */
crc_32_tab = bb_crc32_filltable(0);
clear_bufs(); clear_bufs();
part_nb = 0; 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 long header_bytes; /* number of bytes in gzip header */
static void put_long(ulg n) static void put_long(ulg n)

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@ -84,8 +84,8 @@ typedef struct {
/* The CRC values stored in the block header and calculated from the data */ /* The CRC values stored in the block header and calculated from the data */
unsigned int crc32Table[256],headerCRC, totalCRC, writeCRC; uint32_t headerCRC, totalCRC, writeCRC;
uint32_t *crc32Table;
/* Intermediate buffer and its size (in bytes) */ /* Intermediate buffer and its size (in bytes) */
unsigned int *dbuf, dbufSize; unsigned int *dbuf, dbufSize;
@ -620,7 +620,7 @@ decode_next_byte:
bd->writeCount=previous; bd->writeCount=previous;
return (previous!=RETVAL_LAST_BLOCK) ? previous : gotcount; return (previous!=RETVAL_LAST_BLOCK) ? previous : gotcount;
} }
bd->writeCRC=0xffffffffUL; bd->writeCRC=~0;
pos=bd->writePos; pos=bd->writePos;
current=bd->writeCurrent; current=bd->writeCurrent;
goto decode_next_byte; goto decode_next_byte;
@ -634,7 +634,7 @@ static int start_bunzip(bunzip_data **bdp, int in_fd, unsigned char *inbuf,
int len) int len)
{ {
bunzip_data *bd; bunzip_data *bd;
unsigned int i,j,c; unsigned int i;
const unsigned int BZh0=(((unsigned int)'B')<<24)+(((unsigned int)'Z')<<16) const unsigned int BZh0=(((unsigned int)'B')<<24)+(((unsigned int)'Z')<<16)
+(((unsigned int)'h')<<8)+(unsigned int)'0'; +(((unsigned int)'h')<<8)+(unsigned int)'0';
@ -657,12 +657,7 @@ static int start_bunzip(bunzip_data **bdp, int in_fd, unsigned char *inbuf,
/* Init the CRC32 table (big endian) */ /* Init the CRC32 table (big endian) */
for(i=0;i<256;i++) { bd->crc32Table = bb_crc32_filltable(1);
c=i<<24;
for(j=8;j;j--)
c=c&0x80000000 ? (c<<1)^0x04c11db7 : (c<<1);
bd->crc32Table[i]=c;
}
/* Setup for I/O error handling via longjmp */ /* Setup for I/O error handling via longjmp */

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@ -95,8 +95,8 @@ static unsigned int gunzip_outbuf_count; /* bytes in output buffer */
enum { gunzip_wsize = 0x8000 }; enum { gunzip_wsize = 0x8000 };
static unsigned char *gunzip_window; static unsigned char *gunzip_window;
static unsigned int *gunzip_crc_table; static uint32_t *gunzip_crc_table;
unsigned int gunzip_crc; uint32_t gunzip_crc;
/* If BMAX needs to be larger than 16, then h and x[] should be ulg. */ /* If BMAX needs to be larger than 16, then h and x[] should be ulg. */
#define BMAX 16 /* maximum bit length of any code (16 for explode) */ #define BMAX 16 /* maximum bit length of any code (16 for explode) */
@ -168,35 +168,6 @@ static unsigned int fill_bitbuffer(unsigned int bitbuffer, unsigned int *current
return(bitbuffer); return(bitbuffer);
} }
static void make_gunzip_crc_table(void)
{
const unsigned int poly = 0xedb88320; /* polynomial exclusive-or pattern */
unsigned short i; /* counter for all possible eight bit values */
/* initial shift register value */
gunzip_crc = 0xffffffffL;
gunzip_crc_table = (unsigned int *) xmalloc(256 * sizeof(unsigned int));
/* Compute and print table of CRC's, five per line */
for (i = 0; i < 256; i++) {
unsigned int table_entry; /* crc shift register */
unsigned 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
*/
for (k = 8; k; k--) {
if (table_entry & 1) {
table_entry = (table_entry >> 1) ^ poly;
} else {
table_entry >>= 1;
}
}
gunzip_crc_table[i] = table_entry;
}
}
/* /*
* Free the malloc'ed tables built by huft_build(), which makes a linked * Free the malloc'ed tables built by huft_build(), which makes a linked
* list of the tables it made, with the links in a dummy first entry of * list of the tables it made, with the links in a dummy first entry of
@ -922,8 +893,9 @@ int inflate_unzip(int in, int out)
gunzip_bb = 0; gunzip_bb = 0;
/* Create the crc table */ /* Create the crc table */
make_gunzip_crc_table(); gunzip_crc_table = bb_crc32_filltable(0);
gunzip_crc = ~0;
/* Allocate space for buffer */ /* Allocate space for buffer */
bytebuffer = xmalloc(bytebuffer_max); bytebuffer = xmalloc(bytebuffer_max);
@ -955,7 +927,7 @@ int inflate_unzip(int in, int out)
int inflate_gunzip(int in, int out) int inflate_gunzip(int in, int out)
{ {
unsigned int stored_crc = 0; uint32_t stored_crc = 0;
unsigned int count; unsigned int count;
inflate_unzip(in, out); inflate_unzip(in, out);
@ -972,7 +944,7 @@ int inflate_gunzip(int in, int out)
} }
/* Validate decompression - crc */ /* Validate decompression - crc */
if (stored_crc != (gunzip_crc ^ 0xffffffffL)) { if (stored_crc != (~gunzip_crc)) {
bb_error_msg("crc error"); bb_error_msg("crc error");
return -1; return -1;
} }

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@ -508,6 +508,8 @@ void md5_begin(md5_ctx_t *ctx);
void md5_hash(const void *data, size_t length, md5_ctx_t *ctx); void md5_hash(const void *data, size_t length, md5_ctx_t *ctx);
void *md5_end(void *resbuf, md5_ctx_t *ctx); void *md5_end(void *resbuf, md5_ctx_t *ctx);
extern uint32_t *bb_crc32_filltable (int endian);
/* busybox.h will include dmalloc later for us, else include it here. */ /* busybox.h will include dmalloc later for us, else include it here. */
#if !defined _BB_INTERNAL_H_ && defined DMALLOC #if !defined _BB_INTERNAL_H_ && defined DMALLOC
#include <dmalloc.h> #include <dmalloc.h>

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@ -13,7 +13,7 @@ LIBBB-n:=
LIBBB-y:= \ LIBBB-y:= \
bb_asprintf.c ask_confirmation.c change_identity.c chomp.c \ bb_asprintf.c ask_confirmation.c change_identity.c chomp.c \
compare_string_array.c concat_path_file.c copy_file.c copyfd.c \ compare_string_array.c concat_path_file.c copy_file.c copyfd.c \
create_icmp_socket.c create_icmp6_socket.c \ crc32.c create_icmp_socket.c create_icmp6_socket.c \
device_open.c dump.c error_msg.c error_msg_and_die.c find_mount_point.c \ device_open.c dump.c error_msg.c error_msg_and_die.c find_mount_point.c \
find_pid_by_name.c find_root_device.c fgets_str.c full_read.c \ find_pid_by_name.c find_root_device.c fgets_str.c full_read.c \
full_write.c get_last_path_component.c get_line_from_file.c \ full_write.c get_last_path_component.c get_line_from_file.c \

40
libbb/crc32.c Normal file
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@ -0,0 +1,40 @@
/* vi: set sw=4 ts=4: */
/*
* CRC32 table fill function
* Copyright (C) 2006 by Rob Sullivan <cogito.ergo.cogito@gmail.com>
* (I can't really claim much credit however, as the algorithm is
* very well-known)
*
* The following function creates a CRC32 table depending on whether
* a big-endian (0x04c11db7) or little-endian (0xedb88320) CRC32 is
* required. Admittedly, there are other CRC32 polynomials floating
* around, but Busybox doesn't use them.
*
* endian = 1: big-endian
* endian = 0: little-endian
*/
#include <stdio.h>
#include <stdlib.h>
#include "libbb.h"
uint32_t *bb_crc32_filltable (int endian) {
uint32_t *crc_table = xmalloc(256 * sizeof(uint32_t));
uint32_t polynomial = endian ? 0x04c11db7 : 0xedb88320;
uint32_t c;
int i, j;
for (i = 0; i < 256; i++) {
c = endian ? (i << 24) : i;
for (j = 8; j; j--) {
if (endian)
c = (c&0x80000000) ? ((c << 1) ^ polynomial) : (c << 1);
else
c = (c&1) ? ((c >> 1) ^ polynomial) : (c >> 1);
}
*crc_table++ = c;
}
return crc_table - 256;
}