Patch from Rob Sullivan to consolidate crc32 table generation.

6 files changed, 65 insertions, 71 deletions

diff --git a/archival/gzip.c b/archival/gzip.c
index fa6e85b66..41ed3a2c7 100644
--- a/archival/gzip.c
+++ b/archival/gzip.c
@@ -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)
diff --git a/archival/libunarchive/decompress_bunzip2.c b/archival/libunarchive/decompress_bunzip2.c
index 3d07d9e03..1879f7255 100644
--- a/archival/libunarchive/decompress_bunzip2.c
+++ b/archival/libunarchive/decompress_bunzip2.c
@@ -84,8 +84,8 @@ typedef struct {
 
 	/* 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) */
 
 	unsigned int *dbuf, dbufSize;
@@ -620,7 +620,7 @@ decode_next_byte:
 		bd->writeCount=previous;
 		return (previous!=RETVAL_LAST_BLOCK) ? previous : gotcount;
 	}
-	bd->writeCRC=0xffffffffUL;
+	bd->writeCRC=~0;
 	pos=bd->writePos;
 	current=bd->writeCurrent;
 	goto decode_next_byte;
@@ -634,7 +634,7 @@ static int start_bunzip(bunzip_data **bdp, int in_fd, unsigned char *inbuf,
 						int len)
 {
 	bunzip_data *bd;
-	unsigned int i,j,c;
+	unsigned int i;
 	const unsigned int BZh0=(((unsigned int)'B')<<24)+(((unsigned int)'Z')<<16)
 							+(((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) */
 
-	for(i=0;i<256;i++) {
-		c=i<<24;
-		for(j=8;j;j--)
-			c=c&0x80000000 ? (c<<1)^0x04c11db7 : (c<<1);
-		bd->crc32Table[i]=c;
-	}
+	bd->crc32Table = bb_crc32_filltable(1);
 
 	/* Setup for I/O error handling via longjmp */
 
diff --git a/archival/libunarchive/decompress_unzip.c b/archival/libunarchive/decompress_unzip.c
index 3215697aa..a589bdcd4 100644
--- a/archival/libunarchive/decompress_unzip.c
+++ b/archival/libunarchive/decompress_unzip.c
@@ -95,8 +95,8 @@ static unsigned int gunzip_outbuf_count;	/* bytes in output buffer */
 enum { gunzip_wsize = 0x8000 };
 static unsigned char *gunzip_window;
 
-static unsigned int *gunzip_crc_table;
-unsigned int gunzip_crc;
+static uint32_t *gunzip_crc_table;
+uint32_t gunzip_crc;
 
 /* 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) */
@@ -168,35 +168,6 @@ static unsigned int fill_bitbuffer(unsigned int bitbuffer, unsigned int *current
 	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
  * 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;
 
 	/* Create the crc table */
-	make_gunzip_crc_table();
-
+	gunzip_crc_table = bb_crc32_filltable(0);
+	gunzip_crc = ~0;
+	
 	/* Allocate space for buffer */
 	bytebuffer = xmalloc(bytebuffer_max);
 
@@ -955,7 +927,7 @@ int inflate_unzip(int in, int out)
 
 int inflate_gunzip(int in, int out)
 {
-	unsigned int stored_crc = 0;
+	uint32_t stored_crc = 0;
 	unsigned int count;
 
 	inflate_unzip(in, out);
@@ -972,7 +944,7 @@ int inflate_gunzip(int in, int out)
 	}
 
 	/* Validate decompression - crc */
-	if (stored_crc != (gunzip_crc ^ 0xffffffffL)) {
+	if (stored_crc != (~gunzip_crc)) {
 		bb_error_msg("crc error");
 		return -1;
 	}
diff --git a/include/libbb.h b/include/libbb.h
index 64a235a9f..edbc58206 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -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_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.  */
 #if !defined _BB_INTERNAL_H_ && defined DMALLOC
 #include <dmalloc.h>
diff --git a/libbb/Makefile.in b/libbb/Makefile.in
index 338a5be97..2d9a1745d 100644
--- a/libbb/Makefile.in
+++ b/libbb/Makefile.in
@@ -13,7 +13,7 @@ LIBBB-n:=
 LIBBB-y:= \
 	bb_asprintf.c ask_confirmation.c change_identity.c chomp.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 \
 	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 \
diff --git a/libbb/crc32.c b/libbb/crc32.c
new file mode 100644
index 000000000..03609952d
--- /dev/null
+++ b/libbb/crc32.c
@@ -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;
+}