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authorDenis Vlasenko <vda.linux@googlemail.com>2007-01-07 19:38:26 +0000
committerDenis Vlasenko <vda.linux@googlemail.com>2007-01-07 19:38:26 +0000
commited0f6db35e02ccd0d8c22337639463a05e3efea1 (patch)
tree18ca97d9c2768b73e721d8b54c788fd82344f268 /archival
parent30551fd6da3c13b96cebf3ec96ede8d54cf365f8 (diff)
downloadbusybox-ed0f6db35e02ccd0d8c22337639463a05e3efea1.tar.gz
gzip cleanup part #3
Diffstat (limited to 'archival')
-rw-r--r--archival/gzip.c139
1 files changed, 66 insertions, 73 deletions
diff --git a/archival/gzip.c b/archival/gzip.c
index a16e36978..dcbcae0b3 100644
--- a/archival/gzip.c
+++ b/archival/gzip.c
@@ -61,8 +61,6 @@ aa: 85.1% -- replaced with aa.gz
# endif
#endif
-#define NO_FILE (-1) /* in memory compression */
-
#define PACK_MAGIC "\037\036" /* Magic header for packed files */
#define GZIP_MAGIC "\037\213" /* Magic header for gzip files, 1F 8B */
#define OLD_GZIP_MAGIC "\037\236" /* Magic header for gzip 0.5 = freeze 1.x */
@@ -161,28 +159,26 @@ typedef unsigned short ush;
typedef unsigned long ulg;
- /* from zip.c: */
+/* from zip.c: */
static int zip(int in, int out);
static unsigned file_read(void *buf, unsigned size);
- /* from deflate.c */
+/* from deflate.c */
static void lm_init(ush * flags);
static ulg deflate(void);
- /* from trees.c */
+/* from trees.c */
static void ct_init(ush * attr, int *methodp);
static int ct_tally(int dist, int lc);
static ulg flush_block(char *buf, ulg stored_len, int eof);
- /* from bits.c */
+/* from bits.c */
static void bi_init(int zipfile);
static void send_bits(int value, int length);
static unsigned bi_reverse(unsigned value, int length);
static void bi_windup(void);
static void copy_block(char *buf, unsigned len, int header);
-static void flush_outbuf(void);
-
/* global buffers */
/* To save memory for 16 bit systems, some arrays are overlaid between
@@ -250,6 +246,20 @@ static ulg bits_sent; /* bit length of the compressed data */
/* ===========================================================================
+ * Write the output buffer outbuf[0..outcnt-1] and update bytes_out.
+ * (used for the compressed data only)
+ */
+static void flush_outbuf(void)
+{
+ if (outcnt == 0)
+ return;
+
+ xwrite(ofd, (char *) outbuf, outcnt);
+ outcnt = 0;
+}
+
+
+/* ===========================================================================
*/
/* put_8bit is used for the compressed output */
#define put_8bit(c) \
@@ -284,6 +294,7 @@ static void put_32bit(ulg n)
outbuf[outcnt++] = (c); \
}
+
/* ===========================================================================
* Clear input and output buffers
*/
@@ -296,29 +307,52 @@ static void clear_bufs(void)
isize = 0L;
}
+
/* ===========================================================================
* Run a set of bytes through the crc shift register. If s is a NULL
* pointer, then initialize the crc shift register contents instead.
* Return the current crc in either case.
*/
+static uint32_t crc = ~0; /* shift register contents */
static uint32_t updcrc(uch * s, unsigned n)
{
- static uint32_t crc = ~0; /* shift register contents */
uint32_t c; /* temporary variable */
if (s == NULL) {
c = ~0;
} else {
c = crc;
- if (n)
- do {
- c = crc_32_tab[((int) c ^ (*s++)) & 0xff] ^ (c >> 8);
- } while (--n);
+ while (n) {
+ c = crc_32_tab[(uch)(c ^ *s++)] ^ (c >> 8);
+ n--;
+ }
}
crc = c;
return c;
}
+
+/* ===========================================================================
+ * Read a new buffer from the current input file, perform end-of-line
+ * translation, and update the crc and input file size.
+ * IN assertion: size >= 2 (for end-of-line translation)
+ */
+static unsigned file_read(void *buf, unsigned size)
+{
+ unsigned len;
+
+ Assert(insize == 0, "inbuf not empty");
+
+ len = safe_read(ifd, buf, size);
+ if (len == (unsigned)(-1) || len == 0)
+ return len;
+
+ updcrc(buf, len);
+ isize += len;
+ return len;
+}
+
+
/* ===========================================================================
* Initialize the bit string routines.
*/
@@ -332,6 +366,7 @@ static void bi_init(int zipfile)
#endif
}
+
/* ===========================================================================
* Send a value on a given number of bits.
* IN assertion: length <= 16 and value fits in length bits.
@@ -414,16 +449,6 @@ static void copy_block(char *buf, unsigned len, int header)
}
}
-/* void lm_init (int pack_level, ush *flags)
- * Initialize the "longest match" routines for a new file
- *
- * ulg deflate (void)
- * Processes a new input file and return its compressed length. Sets
- * the compressed length, crc, deflate flags and internal file
- * attributes.
- */
-
-
/* ===========================================================================
* Configuration parameters
*/
@@ -517,7 +542,7 @@ static unsigned ins_h; /* hash index of string to be inserted */
/* Number of bits by which ins_h and del_h must be shifted at each
* input step. It must be such that after MIN_MATCH steps, the oldest
* byte no longer takes part in the hash key, that is:
- * H_SHIFT * MIN_MATCH >= HASH_BITS
+ * H_SHIFT * MIN_MATCH >= HASH_BITS
*/
static unsigned int prev_length;
@@ -664,8 +689,7 @@ static int longest_match(IPos cur_match)
uch *match; /* matched string */
int len; /* length of current match */
int best_len = prev_length; /* best match length so far */
- IPos limit =
- strstart > (IPos) MAX_DIST ? strstart - (IPos) MAX_DIST : NIL;
+ IPos limit = strstart > (IPos) MAX_DIST ? strstart - (IPos) MAX_DIST : 0;
/* Stop when cur_match becomes <= limit. To simplify the code,
* we prevent matches with the string of window index 0.
*/
@@ -739,8 +763,7 @@ static int longest_match(IPos cur_match)
static void check_match(IPos start, IPos match, int length)
{
/* check that the match is indeed a match */
- if (memcmp((char *) window + match,
- (char *) window + start, length) != EQUAL) {
+ if (memcmp(window + match, window + start, length) != EQUAL) {
bb_error_msg(" start %d, match %d, length %d", start, match, length);
bb_error_msg("invalid match");
}
@@ -766,14 +789,13 @@ static void check_match(IPos start, IPos match, int length)
static void fill_window(void)
{
unsigned n, m;
- unsigned more =
- (unsigned) (window_size - (ulg) lookahead - (ulg) strstart);
+ unsigned more = window_size - lookahead - strstart;
/* Amount of free space at the end of the window. */
/* If the window is almost full and there is insufficient lookahead,
* move the upper half to the lower one to make room in the upper half.
*/
- if (more == (unsigned) EOF) {
+ if (more == (unsigned) -1) {
/* Very unlikely, but possible on 16 bit machine if strstart == 0
* and lookahead == 1 (input done one byte at time)
*/
@@ -784,7 +806,7 @@ static void fill_window(void)
*/
Assert(window_size == (ulg) 2 * WSIZE, "no sliding with BIG_MEM");
- memcpy((char *) window, (char *) window + WSIZE, (unsigned) WSIZE);
+ memcpy(window, window + WSIZE, WSIZE);
match_start -= WSIZE;
strstart -= WSIZE; /* we now have strstart >= MAX_DIST: */
@@ -819,13 +841,19 @@ static void fill_window(void)
* IN assertion: strstart is set to the end of the current match.
*/
#define FLUSH_BLOCK(eof) \
- flush_block(block_start >= 0L ? (char*)&window[(unsigned)block_start] : \
- (char*)NULL, (long)strstart - block_start, (eof))
+ flush_block(block_start >= 0L \
+ ? (char*)&window[(unsigned)block_start] \
+ : (char*)NULL, \
+ (long)strstart - block_start, (eof))
/* ===========================================================================
* Same as above, but achieves better compression. We use a lazy
* evaluation for matches: a match is finally adopted only if there is
* no better match at the next window position.
+ *
+ * Processes a new input file and return its compressed length. Sets
+ * the compressed length, crc, deflate flags and internal file
+ * attributes.
*/
static ulg deflate(void)
{
@@ -930,6 +958,7 @@ static ulg deflate(void)
return FLUSH_BLOCK(1); /* eof */
}
+
/* ======================================================================== */
static void abort_gzip(int ATTRIBUTE_UNUSED ignored)
{
@@ -2181,8 +2210,6 @@ static void set_file_type(void)
}
}
-static uint32_t crc; /* crc on uncompressed file data */
-
/* ===========================================================================
* Deflate in to out.
* IN assertions: the input and output buffers are cleared.
@@ -2209,7 +2236,7 @@ static int zip(int in, int out)
put_32bit(time_stamp);
/* Write deflated file to zip file */
- crc = 0;
+ crc = ~0;
bi_init(out);
ct_init(&attr, &method);
@@ -2218,46 +2245,12 @@ static int zip(int in, int out)
put_8bit((uch) deflate_flags); /* extra flags */
put_8bit(3); /* OS identifier = 3 (Unix) */
- (void) deflate();
+ deflate();
/* Write the crc and uncompressed size */
- put_32bit(crc);
+ put_32bit(~crc);
put_32bit(isize);
flush_outbuf();
return 0;
}
-
-/* ===========================================================================
- * Read a new buffer from the current input file, perform end-of-line
- * translation, and update the crc and input file size.
- * IN assertion: size >= 2 (for end-of-line translation)
- */
-static unsigned file_read(void *buf, unsigned size)
-{
- unsigned len;
-
- Assert(insize == 0, "inbuf not empty");
-
- len = read(ifd, buf, size);
- if (len == (unsigned)(-1) || len == 0)
- return len;
-
- crc = ~updcrc((uch *) buf, len);
- isize += len;
- return len;
-}
-
-/* ===========================================================================
- * Write the output buffer outbuf[0..outcnt-1] and update bytes_out.
- * (used for the compressed data only)
- */
-static void flush_outbuf(void)
-{
- if (outcnt == 0)
- return;
-
- xwrite(ofd, (char *) outbuf, outcnt);
- outcnt = 0;
-}
-