patch-2.4.20 linux-2.4.20/lib/zlib_deflate/deflate.c
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- Lines: 1251
- Date:
Thu Nov 28 15:53:15 2002
- Orig file:
linux-2.4.19/lib/zlib_deflate/deflate.c
- Orig date:
Wed Dec 31 16:00:00 1969
diff -urN linux-2.4.19/lib/zlib_deflate/deflate.c linux-2.4.20/lib/zlib_deflate/deflate.c
@@ -0,0 +1,1250 @@
+/* +++ deflate.c */
+/* deflate.c -- compress data using the deflation algorithm
+ * Copyright (C) 1995-1996 Jean-loup Gailly.
+ * For conditions of distribution and use, see copyright notice in zlib.h
+ */
+
+/*
+ * ALGORITHM
+ *
+ * The "deflation" process depends on being able to identify portions
+ * of the input text which are identical to earlier input (within a
+ * sliding window trailing behind the input currently being processed).
+ *
+ * The most straightforward technique turns out to be the fastest for
+ * most input files: try all possible matches and select the longest.
+ * The key feature of this algorithm is that insertions into the string
+ * dictionary are very simple and thus fast, and deletions are avoided
+ * completely. Insertions are performed at each input character, whereas
+ * string matches are performed only when the previous match ends. So it
+ * is preferable to spend more time in matches to allow very fast string
+ * insertions and avoid deletions. The matching algorithm for small
+ * strings is inspired from that of Rabin & Karp. A brute force approach
+ * is used to find longer strings when a small match has been found.
+ * A similar algorithm is used in comic (by Jan-Mark Wams) and freeze
+ * (by Leonid Broukhis).
+ * A previous version of this file used a more sophisticated algorithm
+ * (by Fiala and Greene) which is guaranteed to run in linear amortized
+ * time, but has a larger average cost, uses more memory and is patented.
+ * However the F&G algorithm may be faster for some highly redundant
+ * files if the parameter max_chain_length (described below) is too large.
+ *
+ * ACKNOWLEDGEMENTS
+ *
+ * The idea of lazy evaluation of matches is due to Jan-Mark Wams, and
+ * I found it in 'freeze' written by Leonid Broukhis.
+ * Thanks to many people for bug reports and testing.
+ *
+ * REFERENCES
+ *
+ * Deutsch, L.P.,"DEFLATE Compressed Data Format Specification".
+ * Available in ftp://ds.internic.net/rfc/rfc1951.txt
+ *
+ * A description of the Rabin and Karp algorithm is given in the book
+ * "Algorithms" by R. Sedgewick, Addison-Wesley, p252.
+ *
+ * Fiala,E.R., and Greene,D.H.
+ * Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/zutil.h>
+#include "defutil.h"
+
+
+/* ===========================================================================
+ * Function prototypes.
+ */
+typedef enum {
+ need_more, /* block not completed, need more input or more output */
+ block_done, /* block flush performed */
+ finish_started, /* finish started, need only more output at next deflate */
+ finish_done /* finish done, accept no more input or output */
+} block_state;
+
+typedef block_state (*compress_func) OF((deflate_state *s, int flush));
+/* Compression function. Returns the block state after the call. */
+
+local void fill_window OF((deflate_state *s));
+local block_state deflate_stored OF((deflate_state *s, int flush));
+local block_state deflate_fast OF((deflate_state *s, int flush));
+local block_state deflate_slow OF((deflate_state *s, int flush));
+local void lm_init OF((deflate_state *s));
+local void putShortMSB OF((deflate_state *s, uInt b));
+local void flush_pending OF((z_streamp strm));
+local int read_buf OF((z_streamp strm, Bytef *buf, unsigned size));
+local uInt longest_match OF((deflate_state *s, IPos cur_match));
+
+#ifdef DEBUG_ZLIB
+local void check_match OF((deflate_state *s, IPos start, IPos match,
+ int length));
+#endif
+
+/* ===========================================================================
+ * Local data
+ */
+
+#define NIL 0
+/* Tail of hash chains */
+
+#ifndef TOO_FAR
+# define TOO_FAR 4096
+#endif
+/* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
+
+#define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
+/* Minimum amount of lookahead, except at the end of the input file.
+ * See deflate.c for comments about the MIN_MATCH+1.
+ */
+
+/* Values for max_lazy_match, good_match and max_chain_length, depending on
+ * the desired pack level (0..9). The values given below have been tuned to
+ * exclude worst case performance for pathological files. Better values may be
+ * found for specific files.
+ */
+typedef struct config_s {
+ ush good_length; /* reduce lazy search above this match length */
+ ush max_lazy; /* do not perform lazy search above this match length */
+ ush nice_length; /* quit search above this match length */
+ ush max_chain;
+ compress_func func;
+} config;
+
+local const config configuration_table[10] = {
+/* good lazy nice chain */
+/* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
+/* 1 */ {4, 4, 8, 4, deflate_fast}, /* maximum speed, no lazy matches */
+/* 2 */ {4, 5, 16, 8, deflate_fast},
+/* 3 */ {4, 6, 32, 32, deflate_fast},
+
+/* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */
+/* 5 */ {8, 16, 32, 32, deflate_slow},
+/* 6 */ {8, 16, 128, 128, deflate_slow},
+/* 7 */ {8, 32, 128, 256, deflate_slow},
+/* 8 */ {32, 128, 258, 1024, deflate_slow},
+/* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* maximum compression */
+
+/* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
+ * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
+ * meaning.
+ */
+
+#define EQUAL 0
+/* result of memcmp for equal strings */
+
+/* ===========================================================================
+ * Update a hash value with the given input byte
+ * IN assertion: all calls to to UPDATE_HASH are made with consecutive
+ * input characters, so that a running hash key can be computed from the
+ * previous key instead of complete recalculation each time.
+ */
+#define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
+
+
+/* ===========================================================================
+ * Insert string str in the dictionary and set match_head to the previous head
+ * of the hash chain (the most recent string with same hash key). Return
+ * the previous length of the hash chain.
+ * IN assertion: all calls to to INSERT_STRING are made with consecutive
+ * input characters and the first MIN_MATCH bytes of str are valid
+ * (except for the last MIN_MATCH-1 bytes of the input file).
+ */
+#define INSERT_STRING(s, str, match_head) \
+ (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
+ s->prev[(str) & s->w_mask] = match_head = s->head[s->ins_h], \
+ s->head[s->ins_h] = (Pos)(str))
+
+/* ===========================================================================
+ * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
+ * prev[] will be initialized on the fly.
+ */
+#define CLEAR_HASH(s) \
+ s->head[s->hash_size-1] = NIL; \
+ memset((charf *)s->head, 0, (unsigned)(s->hash_size-1)*sizeof(*s->head));
+
+/* ========================================================================= */
+int zlib_deflateInit_(strm, level, version, stream_size)
+ z_streamp strm;
+ int level;
+ const char *version;
+ int stream_size;
+{
+ return zlib_deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS,
+ DEF_MEM_LEVEL,
+ Z_DEFAULT_STRATEGY, version, stream_size);
+ /* To do: ignore strm->next_in if we use it as window */
+}
+
+/* ========================================================================= */
+int zlib_deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
+ version, stream_size)
+ z_streamp strm;
+ int level;
+ int method;
+ int windowBits;
+ int memLevel;
+ int strategy;
+ const char *version;
+ int stream_size;
+{
+ deflate_state *s;
+ int noheader = 0;
+ static char* my_version = ZLIB_VERSION;
+ deflate_workspace *mem;
+
+ ushf *overlay;
+ /* We overlay pending_buf and d_buf+l_buf. This works since the average
+ * output size for (length,distance) codes is <= 24 bits.
+ */
+
+ if (version == Z_NULL || version[0] != my_version[0] ||
+ stream_size != sizeof(z_stream)) {
+ return Z_VERSION_ERROR;
+ }
+ if (strm == Z_NULL) return Z_STREAM_ERROR;
+
+ strm->msg = Z_NULL;
+
+ if (level == Z_DEFAULT_COMPRESSION) level = 6;
+
+ mem = (deflate_workspace *) strm->workspace;
+
+ if (windowBits < 0) { /* undocumented feature: suppress zlib header */
+ noheader = 1;
+ windowBits = -windowBits;
+ }
+ if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
+ windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
+ strategy < 0 || strategy > Z_HUFFMAN_ONLY) {
+ return Z_STREAM_ERROR;
+ }
+ s = (deflate_state *) &(mem->deflate_memory);
+ strm->state = (struct internal_state FAR *)s;
+ s->strm = strm;
+
+ s->noheader = noheader;
+ s->w_bits = windowBits;
+ s->w_size = 1 << s->w_bits;
+ s->w_mask = s->w_size - 1;
+
+ s->hash_bits = memLevel + 7;
+ s->hash_size = 1 << s->hash_bits;
+ s->hash_mask = s->hash_size - 1;
+ s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
+
+ s->window = (Bytef *) mem->window_memory;
+ s->prev = (Posf *) mem->prev_memory;
+ s->head = (Posf *) mem->head_memory;
+
+ s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
+
+ overlay = (ushf *) mem->overlay_memory;
+ s->pending_buf = (uchf *) overlay;
+ s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
+
+ s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
+ s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
+
+ s->level = level;
+ s->strategy = strategy;
+ s->method = (Byte)method;
+
+ return zlib_deflateReset(strm);
+}
+
+/* ========================================================================= */
+int zlib_deflateSetDictionary (strm, dictionary, dictLength)
+ z_streamp strm;
+ const Bytef *dictionary;
+ uInt dictLength;
+{
+ deflate_state *s;
+ uInt length = dictLength;
+ uInt n;
+ IPos hash_head = 0;
+
+ if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL)
+ return Z_STREAM_ERROR;
+
+ s = (deflate_state *) strm->state;
+ if (s->status != INIT_STATE) return Z_STREAM_ERROR;
+
+ strm->adler = zlib_adler32(strm->adler, dictionary, dictLength);
+
+ if (length < MIN_MATCH) return Z_OK;
+ if (length > MAX_DIST(s)) {
+ length = MAX_DIST(s);
+#ifndef USE_DICT_HEAD
+ dictionary += dictLength - length; /* use the tail of the dictionary */
+#endif
+ }
+ memcpy((charf *)s->window, dictionary, length);
+ s->strstart = length;
+ s->block_start = (long)length;
+
+ /* Insert all strings in the hash table (except for the last two bytes).
+ * s->lookahead stays null, so s->ins_h will be recomputed at the next
+ * call of fill_window.
+ */
+ s->ins_h = s->window[0];
+ UPDATE_HASH(s, s->ins_h, s->window[1]);
+ for (n = 0; n <= length - MIN_MATCH; n++) {
+ INSERT_STRING(s, n, hash_head);
+ }
+ if (hash_head) hash_head = 0; /* to make compiler happy */
+ return Z_OK;
+}
+
+/* ========================================================================= */
+int zlib_deflateReset (strm)
+ z_streamp strm;
+{
+ deflate_state *s;
+
+ if (strm == Z_NULL || strm->state == Z_NULL)
+ return Z_STREAM_ERROR;
+
+ strm->total_in = strm->total_out = 0;
+ strm->msg = Z_NULL;
+ strm->data_type = Z_UNKNOWN;
+
+ s = (deflate_state *)strm->state;
+ s->pending = 0;
+ s->pending_out = s->pending_buf;
+
+ if (s->noheader < 0) {
+ s->noheader = 0; /* was set to -1 by deflate(..., Z_FINISH); */
+ }
+ s->status = s->noheader ? BUSY_STATE : INIT_STATE;
+ strm->adler = 1;
+ s->last_flush = Z_NO_FLUSH;
+
+ zlib_tr_init(s);
+ lm_init(s);
+
+ return Z_OK;
+}
+
+/* ========================================================================= */
+int zlib_deflateParams(strm, level, strategy)
+ z_streamp strm;
+ int level;
+ int strategy;
+{
+ deflate_state *s;
+ compress_func func;
+ int err = Z_OK;
+
+ if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
+ s = (deflate_state *) strm->state;
+
+ if (level == Z_DEFAULT_COMPRESSION) {
+ level = 6;
+ }
+ if (level < 0 || level > 9 || strategy < 0 || strategy > Z_HUFFMAN_ONLY) {
+ return Z_STREAM_ERROR;
+ }
+ func = configuration_table[s->level].func;
+
+ if (func != configuration_table[level].func && strm->total_in != 0) {
+ /* Flush the last buffer: */
+ err = zlib_deflate(strm, Z_PARTIAL_FLUSH);
+ }
+ if (s->level != level) {
+ s->level = level;
+ s->max_lazy_match = configuration_table[level].max_lazy;
+ s->good_match = configuration_table[level].good_length;
+ s->nice_match = configuration_table[level].nice_length;
+ s->max_chain_length = configuration_table[level].max_chain;
+ }
+ s->strategy = strategy;
+ return err;
+}
+
+/* =========================================================================
+ * Put a short in the pending buffer. The 16-bit value is put in MSB order.
+ * IN assertion: the stream state is correct and there is enough room in
+ * pending_buf.
+ */
+local void putShortMSB (s, b)
+ deflate_state *s;
+ uInt b;
+{
+ put_byte(s, (Byte)(b >> 8));
+ put_byte(s, (Byte)(b & 0xff));
+}
+
+/* =========================================================================
+ * Flush as much pending output as possible. All deflate() output goes
+ * through this function so some applications may wish to modify it
+ * to avoid allocating a large strm->next_out buffer and copying into it.
+ * (See also read_buf()).
+ */
+local void flush_pending(strm)
+ z_streamp strm;
+{
+ deflate_state *s = (deflate_state *) strm->state;
+ unsigned len = s->pending;
+
+ if (len > strm->avail_out) len = strm->avail_out;
+ if (len == 0) return;
+
+ if (strm->next_out != Z_NULL) {
+ memcpy(strm->next_out, s->pending_out, len);
+ strm->next_out += len;
+ }
+ s->pending_out += len;
+ strm->total_out += len;
+ strm->avail_out -= len;
+ s->pending -= len;
+ if (s->pending == 0) {
+ s->pending_out = s->pending_buf;
+ }
+}
+
+/* ========================================================================= */
+int zlib_deflate (strm, flush)
+ z_streamp strm;
+ int flush;
+{
+ int old_flush; /* value of flush param for previous deflate call */
+ deflate_state *s;
+
+ if (strm == Z_NULL || strm->state == Z_NULL ||
+ flush > Z_FINISH || flush < 0) {
+ return Z_STREAM_ERROR;
+ }
+ s = (deflate_state *) strm->state;
+
+ if ((strm->next_in == Z_NULL && strm->avail_in != 0) ||
+ (s->status == FINISH_STATE && flush != Z_FINISH)) {
+ return Z_STREAM_ERROR;
+ }
+ if (strm->avail_out == 0) return Z_BUF_ERROR;
+
+ s->strm = strm; /* just in case */
+ old_flush = s->last_flush;
+ s->last_flush = flush;
+
+ /* Write the zlib header */
+ if (s->status == INIT_STATE) {
+
+ uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
+ uInt level_flags = (s->level-1) >> 1;
+
+ if (level_flags > 3) level_flags = 3;
+ header |= (level_flags << 6);
+ if (s->strstart != 0) header |= PRESET_DICT;
+ header += 31 - (header % 31);
+
+ s->status = BUSY_STATE;
+ putShortMSB(s, header);
+
+ /* Save the adler32 of the preset dictionary: */
+ if (s->strstart != 0) {
+ putShortMSB(s, (uInt)(strm->adler >> 16));
+ putShortMSB(s, (uInt)(strm->adler & 0xffff));
+ }
+ strm->adler = 1L;
+ }
+
+ /* Flush as much pending output as possible */
+ if (s->pending != 0) {
+ flush_pending(strm);
+ if (strm->avail_out == 0) {
+ /* Since avail_out is 0, deflate will be called again with
+ * more output space, but possibly with both pending and
+ * avail_in equal to zero. There won't be anything to do,
+ * but this is not an error situation so make sure we
+ * return OK instead of BUF_ERROR at next call of deflate:
+ */
+ s->last_flush = -1;
+ return Z_OK;
+ }
+
+ /* Make sure there is something to do and avoid duplicate consecutive
+ * flushes. For repeated and useless calls with Z_FINISH, we keep
+ * returning Z_STREAM_END instead of Z_BUFF_ERROR.
+ */
+ } else if (strm->avail_in == 0 && flush <= old_flush &&
+ flush != Z_FINISH) {
+ return Z_BUF_ERROR;
+ }
+
+ /* User must not provide more input after the first FINISH: */
+ if (s->status == FINISH_STATE && strm->avail_in != 0) {
+ return Z_BUF_ERROR;
+ }
+
+ /* Start a new block or continue the current one.
+ */
+ if (strm->avail_in != 0 || s->lookahead != 0 ||
+ (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
+ block_state bstate;
+
+ bstate = (*(configuration_table[s->level].func))(s, flush);
+
+ if (bstate == finish_started || bstate == finish_done) {
+ s->status = FINISH_STATE;
+ }
+ if (bstate == need_more || bstate == finish_started) {
+ if (strm->avail_out == 0) {
+ s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
+ }
+ return Z_OK;
+ /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
+ * of deflate should use the same flush parameter to make sure
+ * that the flush is complete. So we don't have to output an
+ * empty block here, this will be done at next call. This also
+ * ensures that for a very small output buffer, we emit at most
+ * one empty block.
+ */
+ }
+ if (bstate == block_done) {
+ if (flush == Z_PARTIAL_FLUSH) {
+ zlib_tr_align(s);
+ } else if (flush == Z_PACKET_FLUSH) {
+ /* Output just the 3-bit `stored' block type value,
+ but not a zero length. */
+ zlib_tr_stored_type_only(s);
+ } else { /* FULL_FLUSH or SYNC_FLUSH */
+ zlib_tr_stored_block(s, (char*)0, 0L, 0);
+ /* For a full flush, this empty block will be recognized
+ * as a special marker by inflate_sync().
+ */
+ if (flush == Z_FULL_FLUSH) {
+ CLEAR_HASH(s); /* forget history */
+ }
+ }
+ flush_pending(strm);
+ if (strm->avail_out == 0) {
+ s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
+ return Z_OK;
+ }
+ }
+ }
+ Assert(strm->avail_out > 0, "bug2");
+
+ if (flush != Z_FINISH) return Z_OK;
+ if (s->noheader) return Z_STREAM_END;
+
+ /* Write the zlib trailer (adler32) */
+ putShortMSB(s, (uInt)(strm->adler >> 16));
+ putShortMSB(s, (uInt)(strm->adler & 0xffff));
+ flush_pending(strm);
+ /* If avail_out is zero, the application will call deflate again
+ * to flush the rest.
+ */
+ s->noheader = -1; /* write the trailer only once! */
+ return s->pending != 0 ? Z_OK : Z_STREAM_END;
+}
+
+/* ========================================================================= */
+int zlib_deflateEnd (strm)
+ z_streamp strm;
+{
+ int status;
+ deflate_state *s;
+
+ if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
+ s = (deflate_state *) strm->state;
+
+ status = s->status;
+ if (status != INIT_STATE && status != BUSY_STATE &&
+ status != FINISH_STATE) {
+ return Z_STREAM_ERROR;
+ }
+
+ strm->state = Z_NULL;
+
+ return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
+}
+
+/* =========================================================================
+ * Copy the source state to the destination state.
+ */
+int zlib_deflateCopy (dest, source)
+ z_streamp dest;
+ z_streamp source;
+{
+#ifdef MAXSEG_64K
+ return Z_STREAM_ERROR;
+#else
+ deflate_state *ds;
+ deflate_state *ss;
+ ushf *overlay;
+ deflate_workspace *mem;
+
+
+ if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) {
+ return Z_STREAM_ERROR;
+ }
+
+ ss = (deflate_state *) source->state;
+
+ *dest = *source;
+
+ mem = (deflate_workspace *) dest->workspace;
+
+ ds = &(mem->deflate_memory);
+
+ dest->state = (struct internal_state FAR *) ds;
+ *ds = *ss;
+ ds->strm = dest;
+
+ ds->window = (Bytef *) mem->window_memory;
+ ds->prev = (Posf *) mem->prev_memory;
+ ds->head = (Posf *) mem->head_memory;
+ overlay = (ushf *) mem->overlay_memory;
+ ds->pending_buf = (uchf *) overlay;
+
+ memcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
+ memcpy(ds->prev, ss->prev, ds->w_size * sizeof(Pos));
+ memcpy(ds->head, ss->head, ds->hash_size * sizeof(Pos));
+ memcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
+
+ ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
+ ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
+ ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
+
+ ds->l_desc.dyn_tree = ds->dyn_ltree;
+ ds->d_desc.dyn_tree = ds->dyn_dtree;
+ ds->bl_desc.dyn_tree = ds->bl_tree;
+
+ return Z_OK;
+#endif
+}
+
+/* ===========================================================================
+ * Read a new buffer from the current input stream, update the adler32
+ * and total number of bytes read. All deflate() input goes through
+ * this function so some applications may wish to modify it to avoid
+ * allocating a large strm->next_in buffer and copying from it.
+ * (See also flush_pending()).
+ */
+local int read_buf(strm, buf, size)
+ z_streamp strm;
+ Bytef *buf;
+ unsigned size;
+{
+ unsigned len = strm->avail_in;
+
+ if (len > size) len = size;
+ if (len == 0) return 0;
+
+ strm->avail_in -= len;
+
+ if (!((deflate_state *)(strm->state))->noheader) {
+ strm->adler = zlib_adler32(strm->adler, strm->next_in, len);
+ }
+ memcpy(buf, strm->next_in, len);
+ strm->next_in += len;
+ strm->total_in += len;
+
+ return (int)len;
+}
+
+/* ===========================================================================
+ * Initialize the "longest match" routines for a new zlib stream
+ */
+local void lm_init (s)
+ deflate_state *s;
+{
+ s->window_size = (ulg)2L*s->w_size;
+
+ CLEAR_HASH(s);
+
+ /* Set the default configuration parameters:
+ */
+ s->max_lazy_match = configuration_table[s->level].max_lazy;
+ s->good_match = configuration_table[s->level].good_length;
+ s->nice_match = configuration_table[s->level].nice_length;
+ s->max_chain_length = configuration_table[s->level].max_chain;
+
+ s->strstart = 0;
+ s->block_start = 0L;
+ s->lookahead = 0;
+ s->match_length = s->prev_length = MIN_MATCH-1;
+ s->match_available = 0;
+ s->ins_h = 0;
+}
+
+/* ===========================================================================
+ * Set match_start to the longest match starting at the given string and
+ * return its length. Matches shorter or equal to prev_length are discarded,
+ * in which case the result is equal to prev_length and match_start is
+ * garbage.
+ * IN assertions: cur_match is the head of the hash chain for the current
+ * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
+ * OUT assertion: the match length is not greater than s->lookahead.
+ */
+/* For 80x86 and 680x0, an optimized version will be provided in match.asm or
+ * match.S. The code will be functionally equivalent.
+ */
+local uInt longest_match(s, cur_match)
+ deflate_state *s;
+ IPos cur_match; /* current match */
+{
+ unsigned chain_length = s->max_chain_length;/* max hash chain length */
+ register Bytef *scan = s->window + s->strstart; /* current string */
+ register Bytef *match; /* matched string */
+ register int len; /* length of current match */
+ int best_len = s->prev_length; /* best match length so far */
+ int nice_match = s->nice_match; /* stop if match long enough */
+ IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
+ s->strstart - (IPos)MAX_DIST(s) : NIL;
+ /* Stop when cur_match becomes <= limit. To simplify the code,
+ * we prevent matches with the string of window index 0.
+ */
+ Posf *prev = s->prev;
+ uInt wmask = s->w_mask;
+
+#ifdef UNALIGNED_OK
+ /* Compare two bytes at a time. Note: this is not always beneficial.
+ * Try with and without -DUNALIGNED_OK to check.
+ */
+ register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
+ register ush scan_start = *(ushf*)scan;
+ register ush scan_end = *(ushf*)(scan+best_len-1);
+#else
+ register Bytef *strend = s->window + s->strstart + MAX_MATCH;
+ register Byte scan_end1 = scan[best_len-1];
+ register Byte scan_end = scan[best_len];
+#endif
+
+ /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
+ * It is easy to get rid of this optimization if necessary.
+ */
+ Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
+
+ /* Do not waste too much time if we already have a good match: */
+ if (s->prev_length >= s->good_match) {
+ chain_length >>= 2;
+ }
+ /* Do not look for matches beyond the end of the input. This is necessary
+ * to make deflate deterministic.
+ */
+ if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
+
+ Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
+
+ do {
+ Assert(cur_match < s->strstart, "no future");
+ match = s->window + cur_match;
+
+ /* Skip to next match if the match length cannot increase
+ * or if the match length is less than 2:
+ */
+#if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
+ /* This code assumes sizeof(unsigned short) == 2. Do not use
+ * UNALIGNED_OK if your compiler uses a different size.
+ */
+ if (*(ushf*)(match+best_len-1) != scan_end ||
+ *(ushf*)match != scan_start) continue;
+
+ /* It is not necessary to compare scan[2] and match[2] since they are
+ * always equal when the other bytes match, given that the hash keys
+ * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
+ * strstart+3, +5, ... up to strstart+257. We check for insufficient
+ * lookahead only every 4th comparison; the 128th check will be made
+ * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
+ * necessary to put more guard bytes at the end of the window, or
+ * to check more often for insufficient lookahead.
+ */
+ Assert(scan[2] == match[2], "scan[2]?");
+ scan++, match++;
+ do {
+ } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
+ *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
+ *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
+ *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
+ scan < strend);
+ /* The funny "do {}" generates better code on most compilers */
+
+ /* Here, scan <= window+strstart+257 */
+ Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
+ if (*scan == *match) scan++;
+
+ len = (MAX_MATCH - 1) - (int)(strend-scan);
+ scan = strend - (MAX_MATCH-1);
+
+#else /* UNALIGNED_OK */
+
+ if (match[best_len] != scan_end ||
+ match[best_len-1] != scan_end1 ||
+ *match != *scan ||
+ *++match != scan[1]) continue;
+
+ /* The check at best_len-1 can be removed because it will be made
+ * again later. (This heuristic is not always a win.)
+ * It is not necessary to compare scan[2] and match[2] since they
+ * are always equal when the other bytes match, given that
+ * the hash keys are equal and that HASH_BITS >= 8.
+ */
+ scan += 2, match++;
+ Assert(*scan == *match, "match[2]?");
+
+ /* We check for insufficient lookahead only every 8th comparison;
+ * the 256th check will be made at strstart+258.
+ */
+ do {
+ } while (*++scan == *++match && *++scan == *++match &&
+ *++scan == *++match && *++scan == *++match &&
+ *++scan == *++match && *++scan == *++match &&
+ *++scan == *++match && *++scan == *++match &&
+ scan < strend);
+
+ Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
+
+ len = MAX_MATCH - (int)(strend - scan);
+ scan = strend - MAX_MATCH;
+
+#endif /* UNALIGNED_OK */
+
+ if (len > best_len) {
+ s->match_start = cur_match;
+ best_len = len;
+ if (len >= nice_match) break;
+#ifdef UNALIGNED_OK
+ scan_end = *(ushf*)(scan+best_len-1);
+#else
+ scan_end1 = scan[best_len-1];
+ scan_end = scan[best_len];
+#endif
+ }
+ } while ((cur_match = prev[cur_match & wmask]) > limit
+ && --chain_length != 0);
+
+ if ((uInt)best_len <= s->lookahead) return best_len;
+ return s->lookahead;
+}
+
+#ifdef DEBUG_ZLIB
+/* ===========================================================================
+ * Check that the match at match_start is indeed a match.
+ */
+local void check_match(s, start, match, length)
+ deflate_state *s;
+ IPos start, match;
+ int length;
+{
+ /* check that the match is indeed a match */
+ if (memcmp((charf *)s->window + match,
+ (charf *)s->window + start, length) != EQUAL) {
+ fprintf(stderr, " start %u, match %u, length %d\n",
+ start, match, length);
+ do {
+ fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
+ } while (--length != 0);
+ z_error("invalid match");
+ }
+ if (z_verbose > 1) {
+ fprintf(stderr,"\\[%d,%d]", start-match, length);
+ do { putc(s->window[start++], stderr); } while (--length != 0);
+ }
+}
+#else
+# define check_match(s, start, match, length)
+#endif
+
+/* ===========================================================================
+ * Fill the window when the lookahead becomes insufficient.
+ * Updates strstart and lookahead.
+ *
+ * IN assertion: lookahead < MIN_LOOKAHEAD
+ * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
+ * At least one byte has been read, or avail_in == 0; reads are
+ * performed for at least two bytes (required for the zip translate_eol
+ * option -- not supported here).
+ */
+local void fill_window(s)
+ deflate_state *s;
+{
+ register unsigned n, m;
+ register Posf *p;
+ unsigned more; /* Amount of free space at the end of the window. */
+ uInt wsize = s->w_size;
+
+ do {
+ more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
+
+ /* Deal with !@#$% 64K limit: */
+ if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
+ more = wsize;
+
+ } else if (more == (unsigned)(-1)) {
+ /* Very unlikely, but possible on 16 bit machine if strstart == 0
+ * and lookahead == 1 (input done one byte at time)
+ */
+ more--;
+
+ /* 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.
+ */
+ } else if (s->strstart >= wsize+MAX_DIST(s)) {
+
+ memcpy((charf *)s->window, (charf *)s->window+wsize,
+ (unsigned)wsize);
+ s->match_start -= wsize;
+ s->strstart -= wsize; /* we now have strstart >= MAX_DIST */
+ s->block_start -= (long) wsize;
+
+ /* Slide the hash table (could be avoided with 32 bit values
+ at the expense of memory usage). We slide even when level == 0
+ to keep the hash table consistent if we switch back to level > 0
+ later. (Using level 0 permanently is not an optimal usage of
+ zlib, so we don't care about this pathological case.)
+ */
+ n = s->hash_size;
+ p = &s->head[n];
+ do {
+ m = *--p;
+ *p = (Pos)(m >= wsize ? m-wsize : NIL);
+ } while (--n);
+
+ n = wsize;
+ p = &s->prev[n];
+ do {
+ m = *--p;
+ *p = (Pos)(m >= wsize ? m-wsize : NIL);
+ /* If n is not on any hash chain, prev[n] is garbage but
+ * its value will never be used.
+ */
+ } while (--n);
+ more += wsize;
+ }
+ if (s->strm->avail_in == 0) return;
+
+ /* If there was no sliding:
+ * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
+ * more == window_size - lookahead - strstart
+ * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
+ * => more >= window_size - 2*WSIZE + 2
+ * In the BIG_MEM or MMAP case (not yet supported),
+ * window_size == input_size + MIN_LOOKAHEAD &&
+ * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
+ * Otherwise, window_size == 2*WSIZE so more >= 2.
+ * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
+ */
+ Assert(more >= 2, "more < 2");
+
+ n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
+ s->lookahead += n;
+
+ /* Initialize the hash value now that we have some input: */
+ if (s->lookahead >= MIN_MATCH) {
+ s->ins_h = s->window[s->strstart];
+ UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
+#if MIN_MATCH != 3
+ Call UPDATE_HASH() MIN_MATCH-3 more times
+#endif
+ }
+ /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
+ * but this is not important since only literal bytes will be emitted.
+ */
+
+ } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
+}
+
+/* ===========================================================================
+ * Flush the current block, with given end-of-file flag.
+ * IN assertion: strstart is set to the end of the current match.
+ */
+#define FLUSH_BLOCK_ONLY(s, eof) { \
+ zlib_tr_flush_block(s, (s->block_start >= 0L ? \
+ (charf *)&s->window[(unsigned)s->block_start] : \
+ (charf *)Z_NULL), \
+ (ulg)((long)s->strstart - s->block_start), \
+ (eof)); \
+ s->block_start = s->strstart; \
+ flush_pending(s->strm); \
+ Tracev((stderr,"[FLUSH]")); \
+}
+
+/* Same but force premature exit if necessary. */
+#define FLUSH_BLOCK(s, eof) { \
+ FLUSH_BLOCK_ONLY(s, eof); \
+ if (s->strm->avail_out == 0) return (eof) ? finish_started : need_more; \
+}
+
+/* ===========================================================================
+ * Copy without compression as much as possible from the input stream, return
+ * the current block state.
+ * This function does not insert new strings in the dictionary since
+ * uncompressible data is probably not useful. This function is used
+ * only for the level=0 compression option.
+ * NOTE: this function should be optimized to avoid extra copying from
+ * window to pending_buf.
+ */
+local block_state deflate_stored(s, flush)
+ deflate_state *s;
+ int flush;
+{
+ /* Stored blocks are limited to 0xffff bytes, pending_buf is limited
+ * to pending_buf_size, and each stored block has a 5 byte header:
+ */
+ ulg max_block_size = 0xffff;
+ ulg max_start;
+
+ if (max_block_size > s->pending_buf_size - 5) {
+ max_block_size = s->pending_buf_size - 5;
+ }
+
+ /* Copy as much as possible from input to output: */
+ for (;;) {
+ /* Fill the window as much as possible: */
+ if (s->lookahead <= 1) {
+
+ Assert(s->strstart < s->w_size+MAX_DIST(s) ||
+ s->block_start >= (long)s->w_size, "slide too late");
+
+ fill_window(s);
+ if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more;
+
+ if (s->lookahead == 0) break; /* flush the current block */
+ }
+ Assert(s->block_start >= 0L, "block gone");
+
+ s->strstart += s->lookahead;
+ s->lookahead = 0;
+
+ /* Emit a stored block if pending_buf will be full: */
+ max_start = s->block_start + max_block_size;
+ if (s->strstart == 0 || (ulg)s->strstart >= max_start) {
+ /* strstart == 0 is possible when wraparound on 16-bit machine */
+ s->lookahead = (uInt)(s->strstart - max_start);
+ s->strstart = (uInt)max_start;
+ FLUSH_BLOCK(s, 0);
+ }
+ /* Flush if we may have to slide, otherwise block_start may become
+ * negative and the data will be gone:
+ */
+ if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) {
+ FLUSH_BLOCK(s, 0);
+ }
+ }
+ FLUSH_BLOCK(s, flush == Z_FINISH);
+ return flush == Z_FINISH ? finish_done : block_done;
+}
+
+/* ===========================================================================
+ * Compress as much as possible from the input stream, return the current
+ * block state.
+ * This function does not perform lazy evaluation of matches and inserts
+ * new strings in the dictionary only for unmatched strings or for short
+ * matches. It is used only for the fast compression options.
+ */
+local block_state deflate_fast(s, flush)
+ deflate_state *s;
+ int flush;
+{
+ IPos hash_head = NIL; /* head of the hash chain */
+ int bflush; /* set if current block must be flushed */
+
+ for (;;) {
+ /* Make sure that we always have enough lookahead, except
+ * at the end of the input file. We need MAX_MATCH bytes
+ * for the next match, plus MIN_MATCH bytes to insert the
+ * string following the next match.
+ */
+ if (s->lookahead < MIN_LOOKAHEAD) {
+ fill_window(s);
+ if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
+ return need_more;
+ }
+ if (s->lookahead == 0) break; /* flush the current block */
+ }
+
+ /* Insert the string window[strstart .. strstart+2] in the
+ * dictionary, and set hash_head to the head of the hash chain:
+ */
+ if (s->lookahead >= MIN_MATCH) {
+ INSERT_STRING(s, s->strstart, hash_head);
+ }
+
+ /* Find the longest match, discarding those <= prev_length.
+ * At this point we have always match_length < MIN_MATCH
+ */
+ if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
+ /* To simplify the code, we prevent matches with the string
+ * of window index 0 (in particular we have to avoid a match
+ * of the string with itself at the start of the input file).
+ */
+ if (s->strategy != Z_HUFFMAN_ONLY) {
+ s->match_length = longest_match (s, hash_head);
+ }
+ /* longest_match() sets match_start */
+ }
+ if (s->match_length >= MIN_MATCH) {
+ check_match(s, s->strstart, s->match_start, s->match_length);
+
+ bflush = zlib_tr_tally(s, s->strstart - s->match_start,
+ s->match_length - MIN_MATCH);
+
+ s->lookahead -= s->match_length;
+
+ /* Insert new strings in the hash table only if the match length
+ * is not too large. This saves time but degrades compression.
+ */
+ if (s->match_length <= s->max_insert_length &&
+ s->lookahead >= MIN_MATCH) {
+ s->match_length--; /* string at strstart already in hash table */
+ do {
+ s->strstart++;
+ INSERT_STRING(s, s->strstart, hash_head);
+ /* strstart never exceeds WSIZE-MAX_MATCH, so there are
+ * always MIN_MATCH bytes ahead.
+ */
+ } while (--s->match_length != 0);
+ s->strstart++;
+ } else {
+ s->strstart += s->match_length;
+ s->match_length = 0;
+ s->ins_h = s->window[s->strstart];
+ UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
+#if MIN_MATCH != 3
+ Call UPDATE_HASH() MIN_MATCH-3 more times
+#endif
+ /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
+ * matter since it will be recomputed at next deflate call.
+ */
+ }
+ } else {
+ /* No match, output a literal byte */
+ Tracevv((stderr,"%c", s->window[s->strstart]));
+ bflush = zlib_tr_tally (s, 0, s->window[s->strstart]);
+ s->lookahead--;
+ s->strstart++;
+ }
+ if (bflush) FLUSH_BLOCK(s, 0);
+ }
+ FLUSH_BLOCK(s, flush == Z_FINISH);
+ return flush == Z_FINISH ? finish_done : block_done;
+}
+
+/* ===========================================================================
+ * 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.
+ */
+local block_state deflate_slow(s, flush)
+ deflate_state *s;
+ int flush;
+{
+ IPos hash_head = NIL; /* head of hash chain */
+ int bflush; /* set if current block must be flushed */
+
+ /* Process the input block. */
+ for (;;) {
+ /* Make sure that we always have enough lookahead, except
+ * at the end of the input file. We need MAX_MATCH bytes
+ * for the next match, plus MIN_MATCH bytes to insert the
+ * string following the next match.
+ */
+ if (s->lookahead < MIN_LOOKAHEAD) {
+ fill_window(s);
+ if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
+ return need_more;
+ }
+ if (s->lookahead == 0) break; /* flush the current block */
+ }
+
+ /* Insert the string window[strstart .. strstart+2] in the
+ * dictionary, and set hash_head to the head of the hash chain:
+ */
+ if (s->lookahead >= MIN_MATCH) {
+ INSERT_STRING(s, s->strstart, hash_head);
+ }
+
+ /* Find the longest match, discarding those <= prev_length.
+ */
+ s->prev_length = s->match_length, s->prev_match = s->match_start;
+ s->match_length = MIN_MATCH-1;
+
+ if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
+ s->strstart - hash_head <= MAX_DIST(s)) {
+ /* To simplify the code, we prevent matches with the string
+ * of window index 0 (in particular we have to avoid a match
+ * of the string with itself at the start of the input file).
+ */
+ if (s->strategy != Z_HUFFMAN_ONLY) {
+ s->match_length = longest_match (s, hash_head);
+ }
+ /* longest_match() sets match_start */
+
+ if (s->match_length <= 5 && (s->strategy == Z_FILTERED ||
+ (s->match_length == MIN_MATCH &&
+ s->strstart - s->match_start > TOO_FAR))) {
+
+ /* If prev_match is also MIN_MATCH, match_start is garbage
+ * but we will ignore the current match anyway.
+ */
+ s->match_length = MIN_MATCH-1;
+ }
+ }
+ /* If there was a match at the previous step and the current
+ * match is not better, output the previous match:
+ */
+ if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
+ uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
+ /* Do not insert strings in hash table beyond this. */
+
+ check_match(s, s->strstart-1, s->prev_match, s->prev_length);
+
+ bflush = zlib_tr_tally(s, s->strstart -1 - s->prev_match,
+ s->prev_length - MIN_MATCH);
+
+ /* Insert in hash table all strings up to the end of the match.
+ * strstart-1 and strstart are already inserted. If there is not
+ * enough lookahead, the last two strings are not inserted in
+ * the hash table.
+ */
+ s->lookahead -= s->prev_length-1;
+ s->prev_length -= 2;
+ do {
+ if (++s->strstart <= max_insert) {
+ INSERT_STRING(s, s->strstart, hash_head);
+ }
+ } while (--s->prev_length != 0);
+ s->match_available = 0;
+ s->match_length = MIN_MATCH-1;
+ s->strstart++;
+
+ if (bflush) FLUSH_BLOCK(s, 0);
+
+ } else if (s->match_available) {
+ /* If there was no match at the previous position, output a
+ * single literal. If there was a match but the current match
+ * is longer, truncate the previous match to a single literal.
+ */
+ Tracevv((stderr,"%c", s->window[s->strstart-1]));
+ if (zlib_tr_tally (s, 0, s->window[s->strstart-1])) {
+ FLUSH_BLOCK_ONLY(s, 0);
+ }
+ s->strstart++;
+ s->lookahead--;
+ if (s->strm->avail_out == 0) return need_more;
+ } else {
+ /* There is no previous match to compare with, wait for
+ * the next step to decide.
+ */
+ s->match_available = 1;
+ s->strstart++;
+ s->lookahead--;
+ }
+ }
+ Assert (flush != Z_NO_FLUSH, "no flush?");
+ if (s->match_available) {
+ Tracevv((stderr,"%c", s->window[s->strstart-1]));
+ zlib_tr_tally (s, 0, s->window[s->strstart-1]);
+ s->match_available = 0;
+ }
+ FLUSH_BLOCK(s, flush == Z_FINISH);
+ return flush == Z_FINISH ? finish_done : block_done;
+}
+
+ZEXTERN int ZEXPORT zlib_deflate_workspacesize ()
+{
+ return sizeof(deflate_workspace);
+}
FUNET's LINUX-ADM group, linux-adm@nic.funet.fi
TCL-scripts by Sam Shen (who was at: slshen@lbl.gov)