gzip cleanup part #3
This commit is contained in:
Denis Vlasenko
parent
30551fd6da
commit
ed0f6db35e
129
archival/gzip.c
129
archival/gzip.c
@ -61,8 +61,6 @@ aa: 85.1% -- replaced with aa.gz
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# endif
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#endif
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#define NO_FILE (-1) /* in memory compression */
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#define PACK_MAGIC "\037\036" /* Magic header for packed files */
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#define GZIP_MAGIC "\037\213" /* Magic header for gzip files, 1F 8B */
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#define OLD_GZIP_MAGIC "\037\236" /* Magic header for gzip 0.5 = freeze 1.x */
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@ -181,8 +179,6 @@ static unsigned bi_reverse(unsigned value, int length);
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static void bi_windup(void);
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static void copy_block(char *buf, unsigned len, int header);
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static void flush_outbuf(void);
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/* global buffers */
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/* To save memory for 16 bit systems, some arrays are overlaid between
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@ -249,6 +245,20 @@ static ulg bits_sent; /* bit length of the compressed data */
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#endif
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/* ===========================================================================
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* Write the output buffer outbuf[0..outcnt-1] and update bytes_out.
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* (used for the compressed data only)
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*/
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static void flush_outbuf(void)
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{
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if (outcnt == 0)
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return;
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xwrite(ofd, (char *) outbuf, outcnt);
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outcnt = 0;
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}
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/* ===========================================================================
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*/
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/* put_8bit is used for the compressed output */
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@ -284,6 +294,7 @@ static void put_32bit(ulg n)
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outbuf[outcnt++] = (c); \
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}
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/* ===========================================================================
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* Clear input and output buffers
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*/
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@ -296,29 +307,52 @@ static void clear_bufs(void)
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isize = 0L;
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}
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/* ===========================================================================
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* Run a set of bytes through the crc shift register. If s is a NULL
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* pointer, then initialize the crc shift register contents instead.
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* Return the current crc in either case.
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*/
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static uint32_t crc = ~0; /* shift register contents */
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static uint32_t updcrc(uch * s, unsigned n)
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{
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static uint32_t crc = ~0; /* shift register contents */
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uint32_t c; /* temporary variable */
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if (s == NULL) {
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c = ~0;
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} else {
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c = crc;
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if (n)
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do {
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c = crc_32_tab[((int) c ^ (*s++)) & 0xff] ^ (c >> 8);
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} while (--n);
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while (n) {
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c = crc_32_tab[(uch)(c ^ *s++)] ^ (c >> 8);
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n--;
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}
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}
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crc = c;
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return c;
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}
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/* ===========================================================================
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* Read a new buffer from the current input file, perform end-of-line
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* translation, and update the crc and input file size.
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* IN assertion: size >= 2 (for end-of-line translation)
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*/
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static unsigned file_read(void *buf, unsigned size)
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{
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unsigned len;
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Assert(insize == 0, "inbuf not empty");
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len = safe_read(ifd, buf, size);
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if (len == (unsigned)(-1) || len == 0)
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return len;
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updcrc(buf, len);
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isize += len;
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return len;
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}
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/* ===========================================================================
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* Initialize the bit string routines.
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*/
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@ -332,6 +366,7 @@ static void bi_init(int zipfile)
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#endif
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}
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/* ===========================================================================
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* Send a value on a given number of bits.
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* IN assertion: length <= 16 and value fits in length bits.
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@ -414,16 +449,6 @@ static void copy_block(char *buf, unsigned len, int header)
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}
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}
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/* void lm_init (int pack_level, ush *flags)
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* Initialize the "longest match" routines for a new file
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*
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* ulg deflate (void)
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* Processes a new input file and return its compressed length. Sets
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* the compressed length, crc, deflate flags and internal file
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* attributes.
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*/
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/* ===========================================================================
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* Configuration parameters
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*/
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@ -664,8 +689,7 @@ static int longest_match(IPos cur_match)
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uch *match; /* matched string */
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int len; /* length of current match */
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int best_len = prev_length; /* best match length so far */
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IPos limit =
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strstart > (IPos) MAX_DIST ? strstart - (IPos) MAX_DIST : NIL;
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IPos limit = strstart > (IPos) MAX_DIST ? strstart - (IPos) MAX_DIST : 0;
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/* Stop when cur_match becomes <= limit. To simplify the code,
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* we prevent matches with the string of window index 0.
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*/
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@ -739,8 +763,7 @@ static int longest_match(IPos cur_match)
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static void check_match(IPos start, IPos match, int length)
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{
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/* check that the match is indeed a match */
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if (memcmp((char *) window + match,
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(char *) window + start, length) != EQUAL) {
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if (memcmp(window + match, window + start, length) != EQUAL) {
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bb_error_msg(" start %d, match %d, length %d", start, match, length);
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bb_error_msg("invalid match");
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}
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@ -766,14 +789,13 @@ static void check_match(IPos start, IPos match, int length)
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static void fill_window(void)
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{
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unsigned n, m;
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unsigned more =
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(unsigned) (window_size - (ulg) lookahead - (ulg) strstart);
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unsigned more = window_size - lookahead - strstart;
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/* Amount of free space at the end of the window. */
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/* If the window is almost full and there is insufficient lookahead,
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* move the upper half to the lower one to make room in the upper half.
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*/
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if (more == (unsigned) EOF) {
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if (more == (unsigned) -1) {
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/* Very unlikely, but possible on 16 bit machine if strstart == 0
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* and lookahead == 1 (input done one byte at time)
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*/
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@ -784,7 +806,7 @@ static void fill_window(void)
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*/
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Assert(window_size == (ulg) 2 * WSIZE, "no sliding with BIG_MEM");
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memcpy((char *) window, (char *) window + WSIZE, (unsigned) WSIZE);
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memcpy(window, window + WSIZE, WSIZE);
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match_start -= WSIZE;
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strstart -= WSIZE; /* we now have strstart >= MAX_DIST: */
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@ -819,13 +841,19 @@ static void fill_window(void)
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* IN assertion: strstart is set to the end of the current match.
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*/
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#define FLUSH_BLOCK(eof) \
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flush_block(block_start >= 0L ? (char*)&window[(unsigned)block_start] : \
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(char*)NULL, (long)strstart - block_start, (eof))
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flush_block(block_start >= 0L \
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? (char*)&window[(unsigned)block_start] \
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: (char*)NULL, \
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(long)strstart - block_start, (eof))
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/* ===========================================================================
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* Same as above, but achieves better compression. We use a lazy
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* evaluation for matches: a match is finally adopted only if there is
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* no better match at the next window position.
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*
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* Processes a new input file and return its compressed length. Sets
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* the compressed length, crc, deflate flags and internal file
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* attributes.
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*/
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static ulg deflate(void)
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{
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@ -930,6 +958,7 @@ static ulg deflate(void)
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return FLUSH_BLOCK(1); /* eof */
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}
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/* ======================================================================== */
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static void abort_gzip(int ATTRIBUTE_UNUSED ignored)
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{
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@ -2181,8 +2210,6 @@ static void set_file_type(void)
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}
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}
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static uint32_t crc; /* crc on uncompressed file data */
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/* ===========================================================================
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* Deflate in to out.
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* IN assertions: the input and output buffers are cleared.
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@ -2209,7 +2236,7 @@ static int zip(int in, int out)
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put_32bit(time_stamp);
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/* Write deflated file to zip file */
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crc = 0;
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crc = ~0;
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bi_init(out);
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ct_init(&attr, &method);
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@ -2218,46 +2245,12 @@ static int zip(int in, int out)
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put_8bit((uch) deflate_flags); /* extra flags */
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put_8bit(3); /* OS identifier = 3 (Unix) */
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(void) deflate();
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deflate();
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/* Write the crc and uncompressed size */
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put_32bit(crc);
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put_32bit(~crc);
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put_32bit(isize);
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flush_outbuf();
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return 0;
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}
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/* ===========================================================================
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* Read a new buffer from the current input file, perform end-of-line
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* translation, and update the crc and input file size.
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* IN assertion: size >= 2 (for end-of-line translation)
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*/
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static unsigned file_read(void *buf, unsigned size)
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{
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unsigned len;
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Assert(insize == 0, "inbuf not empty");
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len = read(ifd, buf, size);
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if (len == (unsigned)(-1) || len == 0)
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return len;
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crc = ~updcrc((uch *) buf, len);
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isize += len;
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return len;
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}
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/* ===========================================================================
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* Write the output buffer outbuf[0..outcnt-1] and update bytes_out.
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* (used for the compressed data only)
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*/
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static void flush_outbuf(void)
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{
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if (outcnt == 0)
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return;
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xwrite(ofd, (char *) outbuf, outcnt);
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outcnt = 0;
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}
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