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/* trees.c -- output deflated data using Huffman coding* Copyright (C) 1995-2010 Jean-loup Gailly* detect_data_type() function provided freely by Cosmin Truta, 2006* For conditions of distribution and use, see copyright notice in zlib.h*//** ALGORITHM** The "deflation" process uses several Huffman trees. The more* common source values are represented by shorter bit sequences.** Each code tree is stored in a compressed form which is itself* a Huffman encoding of the lengths of all the code strings (in* ascending order by source values). The actual code strings are* reconstructed from the lengths in the inflate process, as described* in the deflate specification.** REFERENCES** Deutsch, L.P.,"'Deflate' Compressed Data Format Specification".* Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc** Storer, James A.* Data Compression: Methods and Theory, pp. 49-50.* Computer Science Press, 1988. ISBN 0-7167-8156-5.** Sedgewick, R.* Algorithms, p290.* Addison-Wesley, 1983. ISBN 0-201-06672-6.*//* @(#) $Id$ *//* #define GEN_TREES_H */#include "deflate.h"#ifdef DEBUG# include <ctype.h>#endif/* ===========================================================================* Constants*/#define MAX_BL_BITS 7/* Bit length codes must not exceed MAX_BL_BITS bits */#define END_BLOCK 256/* end of block literal code */#define REP_3_6 16/* repeat previous bit length 3-6 times (2 bits of repeat count) */#define REPZ_3_10 17/* repeat a zero length 3-10 times (3 bits of repeat count) */#define REPZ_11_138 18/* repeat a zero length 11-138 times (7 bits of repeat count) */local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */= {0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0};local const int extra_dbits[D_CODES] /* extra bits for each distance code */= {0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13};local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */= {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};local const uch bl_order[BL_CODES]= {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};/* The lengths of the bit length codes are sent in order of decreasing* probability, to avoid transmitting the lengths for unused bit length codes.*/#define Buf_size (8 * 2*sizeof(char))/* Number of bits used within bi_buf. (bi_buf might be implemented on* more than 16 bits on some systems.)*//* ===========================================================================* Local data. These are initialized only once.*/#define DIST_CODE_LEN 512 /* see definition of array dist_code below */#if defined(GEN_TREES_H) || !defined(STDC)/* non ANSI compilers may not accept trees.h */local ct_data static_ltree[L_CODES+2];/* The static literal tree. Since the bit lengths are imposed, there is no* need for the L_CODES extra codes used during heap construction. However* The codes 286 and 287 are needed to build a canonical tree (see _tr_init* below).*/local ct_data static_dtree[D_CODES];/* The static distance tree. (Actually a trivial tree since all codes use* 5 bits.)*/uch _dist_code[DIST_CODE_LEN];/* Distance codes. The first 256 values correspond to the distances* 3 .. 258, the last 256 values correspond to the top 8 bits of* the 15 bit distances.*/uch _length_code[MAX_MATCH-MIN_MATCH+1];/* length code for each normalized match length (0 == MIN_MATCH) */local int base_length[LENGTH_CODES];/* First normalized length for each code (0 = MIN_MATCH) */local int base_dist[D_CODES];/* First normalized distance for each code (0 = distance of 1) */#else# include "trees.h"#endif /* GEN_TREES_H */struct static_tree_desc_s {const ct_data *static_tree; /* static tree or NULL */const intf *extra_bits; /* extra bits for each code or NULL */int extra_base; /* base index for extra_bits */int elems; /* max number of elements in the tree */int max_length; /* max bit length for the codes */};local static_tree_desc static_l_desc ={static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};local static_tree_desc static_d_desc ={static_dtree, extra_dbits, 0, D_CODES, MAX_BITS};local static_tree_desc static_bl_desc ={(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS};/* ===========================================================================* Local (static) routines in this file.*/local void tr_static_init OF((void));local void init_block OF((deflate_state *s));local void pqdownheap OF((deflate_state *s, ct_data *tree, int k));local void gen_bitlen OF((deflate_state *s, tree_desc *desc));local void gen_codes OF((ct_data *tree, int max_code, ushf *bl_count));local void build_tree OF((deflate_state *s, tree_desc *desc));local void scan_tree OF((deflate_state *s, ct_data *tree, int max_code));local void send_tree OF((deflate_state *s, ct_data *tree, int max_code));local int build_bl_tree OF((deflate_state *s));local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,int blcodes));local void compress_block OF((deflate_state *s, ct_data *ltree,ct_data *dtree));local int detect_data_type OF((deflate_state *s));local unsigned bi_reverse OF((unsigned value, int length));local void bi_windup OF((deflate_state *s));local void bi_flush OF((deflate_state *s));local void copy_block OF((deflate_state *s, charf *buf, unsigned len,int header));#ifdef GEN_TREES_Hlocal void gen_trees_header OF((void));#endif#ifndef DEBUG# define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)/* Send a code of the given tree. c and tree must not have side effects */#else /* DEBUG */# define send_code(s, c, tree) \{ if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \send_bits(s, tree[c].Code, tree[c].Len); }#endif/* ===========================================================================* Output a short LSB first on the stream.* IN assertion: there is enough room in pendingBuf.*/#define put_short(s, w) { \put_byte(s, (uch)((w) & 0xff)); \put_byte(s, (uch)((ush)(w) >> 8)); \}/* ===========================================================================* Send a value on a given number of bits.* IN assertion: length <= 16 and value fits in length bits.*/#ifdef DEBUGlocal void send_bits OF((deflate_state *s, int value, int length));local void send_bits(s, value, length)deflate_state *s;int value; /* value to send */int length; /* number of bits */{Tracevv((stderr," l %2d v %4x ", length, value));Assert(length > 0 && length <= 15, "invalid length");s->bits_sent += (ulg)length;/* If not enough room in bi_buf, use (valid) bits from bi_buf and* (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))* unused bits in value.*/if (s->bi_valid > (int)Buf_size - length) {s->bi_buf |= (ush)value << s->bi_valid;put_short(s, s->bi_buf);s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);s->bi_valid += length - Buf_size;} else {s->bi_buf |= (ush)value << s->bi_valid;s->bi_valid += length;}}#else /* !DEBUG */#define send_bits(s, value, length) \{ int len = length;\if (s->bi_valid > (int)Buf_size - len) {\int val = value;\s->bi_buf |= (ush)val << s->bi_valid;\put_short(s, s->bi_buf);\s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\s->bi_valid += len - Buf_size;\} else {\s->bi_buf |= (ush)(value) << s->bi_valid;\s->bi_valid += len;\}\}#endif /* DEBUG *//* the arguments must not have side effects *//* ===========================================================================* Initialize the various 'constant' tables.*/local void tr_static_init(){#if defined(GEN_TREES_H) || !defined(STDC)static int static_init_done = 0;int n; /* iterates over tree elements */int bits; /* bit counter */int length; /* length value */int code; /* code value */int dist; /* distance index */ush bl_count[MAX_BITS+1];/* number of codes at each bit length for an optimal tree */if (static_init_done) return;/* For some embedded targets, global variables are not initialized: */#ifdef NO_INIT_GLOBAL_POINTERSstatic_l_desc.static_tree = static_ltree;static_l_desc.extra_bits = extra_lbits;static_d_desc.static_tree = static_dtree;static_d_desc.extra_bits = extra_dbits;static_bl_desc.extra_bits = extra_blbits;#endif/* Initialize the mapping length (0..255) -> length code (0..28) */length = 0;for (code = 0; code < LENGTH_CODES-1; code++) {base_length[code] = length;for (n = 0; n < (1<<extra_lbits[code]); n++) {_length_code[length++] = (uch)code;}}Assert (length == 256, "tr_static_init: length != 256");/* Note that the length 255 (match length 258) can be represented* in two different ways: code 284 + 5 bits or code 285, so we* overwrite length_code[255] to use the best encoding:*/_length_code[length-1] = (uch)code;/* Initialize the mapping dist (0..32K) -> dist code (0..29) */dist = 0;for (code = 0 ; code < 16; code++) {base_dist[code] = dist;for (n = 0; n < (1<<extra_dbits[code]); n++) {_dist_code[dist++] = (uch)code;}}Assert (dist == 256, "tr_static_init: dist != 256");dist >>= 7; /* from now on, all distances are divided by 128 */for ( ; code < D_CODES; code++) {base_dist[code] = dist << 7;for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {_dist_code[256 + dist++] = (uch)code;}}Assert (dist == 256, "tr_static_init: 256+dist != 512");/* Construct the codes of the static literal tree */for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;n = 0;while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;/* Codes 286 and 287 do not exist, but we must include them in the* tree construction to get a canonical Huffman tree (longest code* all ones)*/gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);/* The static distance tree is trivial: */for (n = 0; n < D_CODES; n++) {static_dtree[n].Len = 5;static_dtree[n].Code = bi_reverse((unsigned)n, 5);}static_init_done = 1;# ifdef GEN_TREES_Hgen_trees_header();# endif#endif /* defined(GEN_TREES_H) || !defined(STDC) */}/* ===========================================================================* Genererate the file trees.h describing the static trees.*/#ifdef GEN_TREES_H# ifndef DEBUG# include <stdio.h># endif# define SEPARATOR(i, last, width) \((i) == (last)? "\n};\n\n" : \((i) % (width) == (width)-1 ? ",\n" : ", "))void gen_trees_header(){FILE *header = fopen("trees.h", "w");int i;Assert (header != NULL, "Can't open trees.h");fprintf(header,"/* header created automatically with -DGEN_TREES_H */\n\n");fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");for (i = 0; i < L_CODES+2; i++) {fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));}fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");for (i = 0; i < D_CODES; i++) {fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));}fprintf(header, "const uch ZLIB_INTERNAL _dist_code[DIST_CODE_LEN] = {\n");for (i = 0; i < DIST_CODE_LEN; i++) {fprintf(header, "%2u%s", _dist_code[i],SEPARATOR(i, DIST_CODE_LEN-1, 20));}fprintf(header,"const uch ZLIB_INTERNAL _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {fprintf(header, "%2u%s", _length_code[i],SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));}fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");for (i = 0; i < LENGTH_CODES; i++) {fprintf(header, "%1u%s", base_length[i],SEPARATOR(i, LENGTH_CODES-1, 20));}fprintf(header, "local const int base_dist[D_CODES] = {\n");for (i = 0; i < D_CODES; i++) {fprintf(header, "%5u%s", base_dist[i],SEPARATOR(i, D_CODES-1, 10));}fclose(header);}#endif /* GEN_TREES_H *//* ===========================================================================* Initialize the tree data structures for a new zlib stream.*/void ZLIB_INTERNAL _tr_init(s)deflate_state *s;{tr_static_init();s->l_desc.dyn_tree = s->dyn_ltree;s->l_desc.stat_desc = &static_l_desc;s->d_desc.dyn_tree = s->dyn_dtree;s->d_desc.stat_desc = &static_d_desc;s->bl_desc.dyn_tree = s->bl_tree;s->bl_desc.stat_desc = &static_bl_desc;s->bi_buf = 0;s->bi_valid = 0;s->last_eob_len = 8; /* enough lookahead for inflate */#ifdef DEBUGs->compressed_len = 0L;s->bits_sent = 0L;#endif/* Initialize the first block of the first file: */init_block(s);}/* ===========================================================================* Initialize a new block.*/local void init_block(s)deflate_state *s;{int n; /* iterates over tree elements *//* Initialize the trees. */for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0;for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0;for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;s->dyn_ltree[END_BLOCK].Freq = 1;s->opt_len = s->static_len = 0L;s->last_lit = s->matches = 0;}#define SMALLEST 1/* Index within the heap array of least frequent node in the Huffman tree *//* ===========================================================================* Remove the smallest element from the heap and recreate the heap with* one less element. Updates heap and heap_len.*/#define pqremove(s, tree, top) \{\top = s->heap[SMALLEST]; \s->heap[SMALLEST] = s->heap[s->heap_len--]; \pqdownheap(s, tree, SMALLEST); \}/* ===========================================================================* Compares to subtrees, using the tree depth as tie breaker when* the subtrees have equal frequency. This minimizes the worst case length.*/#define smaller(tree, n, m, depth) \(tree[n].Freq < tree[m].Freq || \(tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))/* ===========================================================================* Restore the heap property by moving down the tree starting at node k,* exchanging a node with the smallest of its two sons if necessary, stopping* when the heap property is re-established (each father smaller than its* two sons).*/local void pqdownheap(s, tree, k)deflate_state *s;ct_data *tree; /* the tree to restore */int k; /* node to move down */{int v = s->heap[k];int j = k << 1; /* left son of k */while (j <= s->heap_len) {/* Set j to the smallest of the two sons: */if (j < s->heap_len &&smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {j++;}/* Exit if v is smaller than both sons */if (smaller(tree, v, s->heap[j], s->depth)) break;/* Exchange v with the smallest son */s->heap[k] = s->heap[j]; k = j;/* And continue down the tree, setting j to the left son of k */j <<= 1;}s->heap[k] = v;}/* ===========================================================================* Compute the optimal bit lengths for a tree and update the total bit length* for the current block.* IN assertion: the fields freq and dad are set, heap[heap_max] and* above are the tree nodes sorted by increasing frequency.* OUT assertions: the field len is set to the optimal bit length, the* array bl_count contains the frequencies for each bit length.* The length opt_len is updated; static_len is also updated if stree is* not null.*/local void gen_bitlen(s, desc)deflate_state *s;tree_desc *desc; /* the tree descriptor */{ct_data *tree = desc->dyn_tree;int max_code = desc->max_code;const ct_data *stree = desc->stat_desc->static_tree;const intf *extra = desc->stat_desc->extra_bits;int base = desc->stat_desc->extra_base;int max_length = desc->stat_desc->max_length;int h; /* heap index */int n, m; /* iterate over the tree elements */int bits; /* bit length */int xbits; /* extra bits */ush f; /* frequency */int overflow = 0; /* number of elements with bit length too large */for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;/* In a first pass, compute the optimal bit lengths (which may* overflow in the case of the bit length tree).*/tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */for (h = s->heap_max+1; h < HEAP_SIZE; h++) {n = s->heap[h];bits = tree[tree[n].Dad].Len + 1;if (bits > max_length) bits = max_length, overflow++;tree[n].Len = (ush)bits;/* We overwrite tree[n].Dad which is no longer needed */if (n > max_code) continue; /* not a leaf node */s->bl_count[bits]++;xbits = 0;if (n >= base) xbits = extra[n-base];f = tree[n].Freq;s->opt_len += (ulg)f * (bits + xbits);if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);}if (overflow == 0) return;Trace((stderr,"\nbit length overflow\n"));/* This happens for example on obj2 and pic of the Calgary corpus *//* Find the first bit length which could increase: */do {bits = max_length-1;while (s->bl_count[bits] == 0) bits--;s->bl_count[bits]--; /* move one leaf down the tree */s->bl_count[bits+1] += 2; /* move one overflow item as its brother */s->bl_count[max_length]--;/* The brother of the overflow item also moves one step up,* but this does not affect bl_count[max_length]*/overflow -= 2;} while (overflow > 0);/* Now recompute all bit lengths, scanning in increasing frequency.* h is still equal to HEAP_SIZE. (It is simpler to reconstruct all* lengths instead of fixing only the wrong ones. This idea is taken* from 'ar' written by Haruhiko Okumura.)*/for (bits = max_length; bits != 0; bits--) {n = s->bl_count[bits];while (n != 0) {m = s->heap[--h];if (m > max_code) continue;if ((unsigned) tree[m].Len != (unsigned) bits) {Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));s->opt_len += ((long)bits - (long)tree[m].Len)*(long)tree[m].Freq;tree[m].Len = (ush)bits;}n--;}}}/* ===========================================================================* Generate the codes for a given tree and bit counts (which need not be* optimal).* IN assertion: the array bl_count contains the bit length statistics for* the given tree and the field len is set for all tree elements.* OUT assertion: the field code is set for all tree elements of non* zero code length.*/local void gen_codes (tree, max_code, bl_count)ct_data *tree; /* the tree to decorate */int max_code; /* largest code with non zero frequency */ushf *bl_count; /* number of codes at each bit length */{ush next_code[MAX_BITS+1]; /* next code value for each bit length */ush code = 0; /* running code value */int bits; /* bit index */int n; /* code index *//* The distribution counts are first used to generate the code values* without bit reversal.*/for (bits = 1; bits <= MAX_BITS; bits++) {next_code[bits] = code = (code + bl_count[bits-1]) << 1;}/* Check that the bit counts in bl_count are consistent. The last code* must be all ones.*/Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,"inconsistent bit counts");Tracev((stderr,"\ngen_codes: max_code %d ", max_code));for (n = 0; n <= max_code; n++) {int len = tree[n].Len;if (len == 0) continue;/* Now reverse the bits */tree[n].Code = bi_reverse(next_code[len]++, len);Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));}}/* ===========================================================================* Construct one Huffman tree and assigns the code bit strings and lengths.* Update the total bit length for the current block.* IN assertion: the field freq is set for all tree elements.* OUT assertions: the fields len and code are set to the optimal bit length* and corresponding code. The length opt_len is updated; static_len is* also updated if stree is not null. The field max_code is set.*/local void build_tree(s, desc)deflate_state *s;tree_desc *desc; /* the tree descriptor */{ct_data *tree = desc->dyn_tree;const ct_data *stree = desc->stat_desc->static_tree;int elems = desc->stat_desc->elems;int n, m; /* iterate over heap elements */int max_code = -1; /* largest code with non zero frequency */int node; /* new node being created *//* Construct the initial heap, with least frequent element in* heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].* heap[0] is not used.*/s->heap_len = 0, s->heap_max = HEAP_SIZE;for (n = 0; n < elems; n++) {if (tree[n].Freq != 0) {s->heap[++(s->heap_len)] = max_code = n;s->depth[n] = 0;} else {tree[n].Len = 0;}}/* The pkzip format requires that at least one distance code exists,* and that at least one bit should be sent even if there is only one* possible code. So to avoid special checks later on we force at least* two codes of non zero frequency.*/while (s->heap_len < 2) {node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);tree[node].Freq = 1;s->depth[node] = 0;s->opt_len--; if (stree) s->static_len -= stree[node].Len;/* node is 0 or 1 so it does not have extra bits */}desc->max_code = max_code;/* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,* establish sub-heaps of increasing lengths:*/for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);/* Construct the Huffman tree by repeatedly combining the least two* frequent nodes.*/node = elems; /* next internal node of the tree */do {pqremove(s, tree, n); /* n = node of least frequency */m = s->heap[SMALLEST]; /* m = node of next least frequency */s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */s->heap[--(s->heap_max)] = m;/* Create a new node father of n and m */tree[node].Freq = tree[n].Freq + tree[m].Freq;s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?s->depth[n] : s->depth[m]) + 1);tree[n].Dad = tree[m].Dad = (ush)node;#ifdef DUMP_BL_TREEif (tree == s->bl_tree) {fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);}#endif/* and insert the new node in the heap */s->heap[SMALLEST] = node++;pqdownheap(s, tree, SMALLEST);} while (s->heap_len >= 2);s->heap[--(s->heap_max)] = s->heap[SMALLEST];/* At this point, the fields freq and dad are set. We can now* generate the bit lengths.*/gen_bitlen(s, (tree_desc *)desc);/* The field len is now set, we can generate the bit codes */gen_codes ((ct_data *)tree, max_code, s->bl_count);}/* ===========================================================================* Scan a literal or distance tree to determine the frequencies of the codes* in the bit length tree.*/local void scan_tree (s, tree, max_code)deflate_state *s;ct_data *tree; /* the tree to be scanned */int max_code; /* and its largest code of non zero frequency */{int n; /* iterates over all tree elements */int prevlen = -1; /* last emitted length */int curlen; /* length of current code */int nextlen = tree[0].Len; /* length of next code */int count = 0; /* repeat count of the current code */int max_count = 7; /* max repeat count */int min_count = 4; /* min repeat count */if (nextlen == 0) max_count = 138, min_count = 3;tree[max_code+1].Len = (ush)0xffff; /* guard */for (n = 0; n <= max_code; n++) {curlen = nextlen; nextlen = tree[n+1].Len;if (++count < max_count && curlen == nextlen) {continue;} else if (count < min_count) {s->bl_tree[curlen].Freq += count;} else if (curlen != 0) {if (curlen != prevlen) s->bl_tree[curlen].Freq++;s->bl_tree[REP_3_6].Freq++;} else if (count <= 10) {s->bl_tree[REPZ_3_10].Freq++;} else {s->bl_tree[REPZ_11_138].Freq++;}count = 0; prevlen = curlen;if (nextlen == 0) {max_count = 138, min_count = 3;} else if (curlen == nextlen) {max_count = 6, min_count = 3;} else {max_count = 7, min_count = 4;}}}/* ===========================================================================* Send a literal or distance tree in compressed form, using the codes in* bl_tree.*/local void send_tree (s, tree, max_code)deflate_state *s;ct_data *tree; /* the tree to be scanned */int max_code; /* and its largest code of non zero frequency */{int n; /* iterates over all tree elements */int prevlen = -1; /* last emitted length */int curlen; /* length of current code */int nextlen = tree[0].Len; /* length of next code */int count = 0; /* repeat count of the current code */int max_count = 7; /* max repeat count */int min_count = 4; /* min repeat count *//* tree[max_code+1].Len = -1; */ /* guard already set */if (nextlen == 0) max_count = 138, min_count = 3;for (n = 0; n <= max_code; n++) {curlen = nextlen; nextlen = tree[n+1].Len;if (++count < max_count && curlen == nextlen) {continue;} else if (count < min_count) {do { send_code(s, curlen, s->bl_tree); } while (--count != 0);} else if (curlen != 0) {if (curlen != prevlen) {send_code(s, curlen, s->bl_tree); count--;}Assert(count >= 3 && count <= 6, " 3_6?");send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);} else if (count <= 10) {send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);} else {send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);}count = 0; prevlen = curlen;if (nextlen == 0) {max_count = 138, min_count = 3;} else if (curlen == nextlen) {max_count = 6, min_count = 3;} else {max_count = 7, min_count = 4;}}}/* ===========================================================================* Construct the Huffman tree for the bit lengths and return the index in* bl_order of the last bit length code to send.*/local int build_bl_tree(s)deflate_state *s;{int max_blindex; /* index of last bit length code of non zero freq *//* Determine the bit length frequencies for literal and distance trees */scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);/* Build the bit length tree: */build_tree(s, (tree_desc *)(&(s->bl_desc)));/* opt_len now includes the length of the tree representations, except* the lengths of the bit lengths codes and the 5+5+4 bits for the counts.*//* Determine the number of bit length codes to send. The pkzip format* requires that at least 4 bit length codes be sent. (appnote.txt says* 3 but the actual value used is 4.)*/for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;}/* Update opt_len to include the bit length tree and counts */s->opt_len += 3*(max_blindex+1) + 5+5+4;Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",s->opt_len, s->static_len));return max_blindex;}/* ===========================================================================* Send the header for a block using dynamic Huffman trees: the counts, the* lengths of the bit length codes, the literal tree and the distance tree.* IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.*/local void send_all_trees(s, lcodes, dcodes, blcodes)deflate_state *s;int lcodes, dcodes, blcodes; /* number of codes for each tree */{int rank; /* index in bl_order */Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,"too many codes");Tracev((stderr, "\nbl counts: "));send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */send_bits(s, dcodes-1, 5);send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */for (rank = 0; rank < blcodes; rank++) {Tracev((stderr, "\nbl code %2d ", bl_order[rank]));send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);}Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));}/* ===========================================================================* Send a stored block*/void ZLIB_INTERNAL _tr_stored_block(s, buf, stored_len, last)deflate_state *s;charf *buf; /* input block */ulg stored_len; /* length of input block */int last; /* one if this is the last block for a file */{send_bits(s, (STORED_BLOCK<<1)+last, 3); /* send block type */#ifdef DEBUGs->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;s->compressed_len += (stored_len + 4) << 3;#endifcopy_block(s, buf, (unsigned)stored_len, 1); /* with header */}/* ===========================================================================* Send one empty static block to give enough lookahead for inflate.* This takes 10 bits, of which 7 may remain in the bit buffer.* The current inflate code requires 9 bits of lookahead. If the* last two codes for the previous block (real code plus EOB) were coded* on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode* the last real code. In this case we send two empty static blocks instead* of one. (There are no problems if the previous block is stored or fixed.)* To simplify the code, we assume the worst case of last real code encoded* on one bit only.*/void ZLIB_INTERNAL _tr_align(s)deflate_state *s;{send_bits(s, STATIC_TREES<<1, 3);send_code(s, END_BLOCK, static_ltree);#ifdef DEBUGs->compressed_len += 10L; /* 3 for block type, 7 for EOB */#endifbi_flush(s);/* Of the 10 bits for the empty block, we have already sent* (10 - bi_valid) bits. The lookahead for the last real code (before* the EOB of the previous block) was thus at least one plus the length* of the EOB plus what we have just sent of the empty static block.*/if (1 + s->last_eob_len + 10 - s->bi_valid < 9) {send_bits(s, STATIC_TREES<<1, 3);send_code(s, END_BLOCK, static_ltree);#ifdef DEBUGs->compressed_len += 10L;#endifbi_flush(s);}s->last_eob_len = 7;}/* ===========================================================================* Determine the best encoding for the current block: dynamic trees, static* trees or store, and output the encoded block to the zip file.*/void ZLIB_INTERNAL _tr_flush_block(s, buf, stored_len, last)deflate_state *s;charf *buf; /* input block, or NULL if too old */ulg stored_len; /* length of input block */int last; /* one if this is the last block for a file */{ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */int max_blindex = 0; /* index of last bit length code of non zero freq *//* Build the Huffman trees unless a stored block is forced */if (s->level > 0) {/* Check if the file is binary or text */if (s->strm->data_type == Z_UNKNOWN)s->strm->data_type = detect_data_type(s);/* Construct the literal and distance trees */build_tree(s, (tree_desc *)(&(s->l_desc)));Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,s->static_len));build_tree(s, (tree_desc *)(&(s->d_desc)));Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,s->static_len));/* At this point, opt_len and static_len are the total bit lengths of* the compressed block data, excluding the tree representations.*//* Build the bit length tree for the above two trees, and get the index* in bl_order of the last bit length code to send.*/max_blindex = build_bl_tree(s);/* Determine the best encoding. Compute the block lengths in bytes. */opt_lenb = (s->opt_len+3+7)>>3;static_lenb = (s->static_len+3+7)>>3;Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,s->last_lit));if (static_lenb <= opt_lenb) opt_lenb = static_lenb;} else {Assert(buf != (char*)0, "lost buf");opt_lenb = static_lenb = stored_len + 5; /* force a stored block */}#ifdef FORCE_STOREDif (buf != (char*)0) { /* force stored block */#elseif (stored_len+4 <= opt_lenb && buf != (char*)0) {/* 4: two words for the lengths */#endif/* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.* Otherwise we can't have processed more than WSIZE input bytes since* the last block flush, because compression would have been* successful. If LIT_BUFSIZE <= WSIZE, it is never too late to* transform a block into a stored block.*/_tr_stored_block(s, buf, stored_len, last);#ifdef FORCE_STATIC} else if (static_lenb >= 0) { /* force static trees */#else} else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {#endifsend_bits(s, (STATIC_TREES<<1)+last, 3);compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree);#ifdef DEBUGs->compressed_len += 3 + s->static_len;#endif} else {send_bits(s, (DYN_TREES<<1)+last, 3);send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,max_blindex+1);compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree);#ifdef DEBUGs->compressed_len += 3 + s->opt_len;#endif}Assert (s->compressed_len == s->bits_sent, "bad compressed size");/* The above check is made mod 2^32, for files larger than 512 MB* and uLong implemented on 32 bits.*/init_block(s);if (last) {bi_windup(s);#ifdef DEBUGs->compressed_len += 7; /* align on byte boundary */#endif}Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,s->compressed_len-7*last));}/* ===========================================================================* Save the match info and tally the frequency counts. Return true if* the current block must be flushed.*/int ZLIB_INTERNAL _tr_tally (s, dist, lc)deflate_state *s;unsigned dist; /* distance of matched string */unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */{s->d_buf[s->last_lit] = (ush)dist;s->l_buf[s->last_lit++] = (uch)lc;if (dist == 0) {/* lc is the unmatched char */s->dyn_ltree[lc].Freq++;} else {s->matches++;/* Here, lc is the match length - MIN_MATCH */dist--; /* dist = match distance - 1 */Assert((ush)dist < (ush)MAX_DIST(s) &&(ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&(ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match");s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;s->dyn_dtree[d_code(dist)].Freq++;}#ifdef TRUNCATE_BLOCK/* Try to guess if it is profitable to stop the current block here */if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {/* Compute an upper bound for the compressed length */ulg out_length = (ulg)s->last_lit*8L;ulg in_length = (ulg)((long)s->strstart - s->block_start);int dcode;for (dcode = 0; dcode < D_CODES; dcode++) {out_length += (ulg)s->dyn_dtree[dcode].Freq *(5L+extra_dbits[dcode]);}out_length >>= 3;Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",s->last_lit, in_length, out_length,100L - out_length*100L/in_length));if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;}#endifreturn (s->last_lit == s->lit_bufsize-1);/* We avoid equality with lit_bufsize because of wraparound at 64K* on 16 bit machines and because stored blocks are restricted to* 64K-1 bytes.*/}/* ===========================================================================* Send the block data compressed using the given Huffman trees*/local void compress_block(s, ltree, dtree)deflate_state *s;ct_data *ltree; /* literal tree */ct_data *dtree; /* distance tree */{unsigned dist; /* distance of matched string */int lc; /* match length or unmatched char (if dist == 0) */unsigned lx = 0; /* running index in l_buf */unsigned code; /* the code to send */int extra; /* number of extra bits to send */if (s->last_lit != 0) do {dist = s->d_buf[lx];lc = s->l_buf[lx++];if (dist == 0) {send_code(s, lc, ltree); /* send a literal byte */Tracecv(isgraph(lc), (stderr," '%c' ", lc));} else {/* Here, lc is the match length - MIN_MATCH */code = _length_code[lc];send_code(s, code+LITERALS+1, ltree); /* send the length code */extra = extra_lbits[code];if (extra != 0) {lc -= base_length[code];send_bits(s, lc, extra); /* send the extra length bits */}dist--; /* dist is now the match distance - 1 */code = d_code(dist);Assert (code < D_CODES, "bad d_code");send_code(s, code, dtree); /* send the distance code */extra = extra_dbits[code];if (extra != 0) {dist -= base_dist[code];send_bits(s, dist, extra); /* send the extra distance bits */}} /* literal or match pair ? *//* Check that the overlay between pending_buf and d_buf+l_buf is ok: */Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,"pendingBuf overflow");} while (lx < s->last_lit);send_code(s, END_BLOCK, ltree);s->last_eob_len = ltree[END_BLOCK].Len;}/* ===========================================================================* Check if the data type is TEXT or BINARY, using the following algorithm:* - TEXT if the two conditions below are satisfied:* a) There are no non-portable control characters belonging to the* "black list" (0..6, 14..25, 28..31).* b) There is at least one printable character belonging to the* "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).* - BINARY otherwise.* - The following partially-portable control characters form a* "gray list" that is ignored in this detection algorithm:* (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).* IN assertion: the fields Freq of dyn_ltree are set.*/local int detect_data_type(s)deflate_state *s;{/* black_mask is the bit mask of black-listed bytes* set bits 0..6, 14..25, and 28..31* 0xf3ffc07f = binary 11110011111111111100000001111111*/unsigned long black_mask = 0xf3ffc07fUL;int n;/* Check for non-textual ("black-listed") bytes. */for (n = 0; n <= 31; n++, black_mask >>= 1)if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0))return Z_BINARY;/* Check for textual ("white-listed") bytes. */if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0|| s->dyn_ltree[13].Freq != 0)return Z_TEXT;for (n = 32; n < LITERALS; n++)if (s->dyn_ltree[n].Freq != 0)return Z_TEXT;/* There are no "black-listed" or "white-listed" bytes:* this stream either is empty or has tolerated ("gray-listed") bytes only.*/return Z_BINARY;}/* ===========================================================================* Reverse the first len bits of a code, using straightforward code (a faster* method would use a table)* IN assertion: 1 <= len <= 15*/local unsigned bi_reverse(code, len)unsigned code; /* the value to invert */int len; /* its bit length */{register unsigned res = 0;do {res |= code & 1;code >>= 1, res <<= 1;} while (--len > 0);return res >> 1;}/* ===========================================================================* Flush the bit buffer, keeping at most 7 bits in it.*/local void bi_flush(s)deflate_state *s;{if (s->bi_valid == 16) {put_short(s, s->bi_buf);s->bi_buf = 0;s->bi_valid = 0;} else if (s->bi_valid >= 8) {put_byte(s, (Byte)s->bi_buf);s->bi_buf >>= 8;s->bi_valid -= 8;}}/* ===========================================================================* Flush the bit buffer and align the output on a byte boundary*/local void bi_windup(s)deflate_state *s;{if (s->bi_valid > 8) {put_short(s, s->bi_buf);} else if (s->bi_valid > 0) {put_byte(s, (Byte)s->bi_buf);}s->bi_buf = 0;s->bi_valid = 0;#ifdef DEBUGs->bits_sent = (s->bits_sent+7) & ~7;#endif}/* ===========================================================================* Copy a stored block, storing first the length and its* one's complement if requested.*/local void copy_block(s, buf, len, header)deflate_state *s;charf *buf; /* the input data */unsigned len; /* its length */int header; /* true if block header must be written */{bi_windup(s); /* align on byte boundary */s->last_eob_len = 8; /* enough lookahead for inflate */if (header) {put_short(s, (ush)len);put_short(s, (ush)~len);#ifdef DEBUGs->bits_sent += 2*16;#endif}#ifdef DEBUGs->bits_sent += (ulg)len<<3;#endifwhile (len--) {put_byte(s, *buf++);}}