Patch from Rob Sullivan to consolidate crc32 table generation.

1 files changed, 10 insertions, 25 deletions

diff --git a/archival/gzip.c b/archival/gzip.c
index fa6e85b..41ed3a2 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)