1
/* trees.c -- output deflated data using Huffman coding
2
* Copyright (C) 1995-2010 Jean-loup Gailly
3
* detect_data_type() function provided freely by Cosmin Truta, 2006
4
* For conditions of distribution and use, see copyright notice in zlib.h
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* The "deflation" process uses several Huffman trees. The more
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* common source values are represented by shorter bit sequences.
13
* Each code tree is stored in a compressed form which is itself
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* a Huffman encoding of the lengths of all the code strings (in
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* ascending order by source values). The actual code strings are
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* reconstructed from the lengths in the inflate process, as described
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* in the deflate specification.
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* Deutsch, L.P.,"'Deflate' Compressed Data Format Specification".
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* Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc
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* Data Compression: Methods and Theory, pp. 49-50.
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* Computer Science Press, 1988. ISBN 0-7167-8156-5.
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* Addison-Wesley, 1983. ISBN 0-201-06672-6.
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/* @(#) $Id: trees.c,v 1.6 2010/08/22 01:07:03 wtc%google.com Exp $ */
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/* #define GEN_TREES_H */
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/* ===========================================================================
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/* Bit length codes must not exceed MAX_BL_BITS bits */
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/* end of block literal code */
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/* repeat previous bit length 3-6 times (2 bits of repeat count) */
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/* repeat a zero length 3-10 times (3 bits of repeat count) */
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#define REPZ_11_138 18
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/* repeat a zero length 11-138 times (7 bits of repeat count) */
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local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
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= {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};
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local const int extra_dbits[D_CODES] /* extra bits for each distance code */
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= {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};
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local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
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= {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
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local const uch bl_order[BL_CODES]
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= {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
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/* The lengths of the bit length codes are sent in order of decreasing
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* probability, to avoid transmitting the lengths for unused bit length codes.
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#define Buf_size (8 * 2*sizeof(char))
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/* Number of bits used within bi_buf. (bi_buf might be implemented on
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* more than 16 bits on some systems.)
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/* ===========================================================================
83
* Local data. These are initialized only once.
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#define DIST_CODE_LEN 512 /* see definition of array dist_code below */
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#if defined(GEN_TREES_H) || !defined(STDC)
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/* non ANSI compilers may not accept trees.h */
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local ct_data static_ltree[L_CODES+2];
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/* The static literal tree. Since the bit lengths are imposed, there is no
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* need for the L_CODES extra codes used during heap construction. However
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* The codes 286 and 287 are needed to build a canonical tree (see _tr_init
98
local ct_data static_dtree[D_CODES];
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/* The static distance tree. (Actually a trivial tree since all codes use
103
uch _dist_code[DIST_CODE_LEN];
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/* Distance codes. The first 256 values correspond to the distances
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* 3 .. 258, the last 256 values correspond to the top 8 bits of
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* the 15 bit distances.
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uch _length_code[MAX_MATCH-MIN_MATCH+1];
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/* length code for each normalized match length (0 == MIN_MATCH) */
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local int base_length[LENGTH_CODES];
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/* First normalized length for each code (0 = MIN_MATCH) */
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local int base_dist[D_CODES];
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/* First normalized distance for each code (0 = distance of 1) */
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#endif /* GEN_TREES_H */
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struct static_tree_desc_s {
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const ct_data *static_tree; /* static tree or NULL */
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const intf *extra_bits; /* extra bits for each code or NULL */
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int extra_base; /* base index for extra_bits */
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int elems; /* max number of elements in the tree */
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int max_length; /* max bit length for the codes */
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local static_tree_desc static_l_desc =
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{static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
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local static_tree_desc static_d_desc =
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{static_dtree, extra_dbits, 0, D_CODES, MAX_BITS};
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local static_tree_desc static_bl_desc =
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{(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS};
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/* ===========================================================================
140
* Local (static) routines in this file.
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local void tr_static_init OF((void));
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local void init_block OF((deflate_state *s));
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local void pqdownheap OF((deflate_state *s, ct_data *tree, int k));
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local void gen_bitlen OF((deflate_state *s, tree_desc *desc));
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local void gen_codes OF((ct_data *tree, int max_code, ushf *bl_count));
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local void build_tree OF((deflate_state *s, tree_desc *desc));
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local void scan_tree OF((deflate_state *s, ct_data *tree, int max_code));
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local void send_tree OF((deflate_state *s, ct_data *tree, int max_code));
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local int build_bl_tree OF((deflate_state *s));
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local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
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local void compress_block OF((deflate_state *s, ct_data *ltree,
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local int detect_data_type OF((deflate_state *s));
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local unsigned bi_reverse OF((unsigned value, int length));
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local void bi_windup OF((deflate_state *s));
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local void bi_flush OF((deflate_state *s));
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local void copy_block OF((deflate_state *s, charf *buf, unsigned len,
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local void gen_trees_header OF((void));
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# define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
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/* Send a code of the given tree. c and tree must not have side effects */
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# define send_code(s, c, tree) \
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{ if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
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send_bits(s, tree[c].Code, tree[c].Len); }
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/* ===========================================================================
178
* Output a short LSB first on the stream.
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* IN assertion: there is enough room in pendingBuf.
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#define put_short(s, w) { \
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put_byte(s, (uch)((w) & 0xff)); \
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put_byte(s, (uch)((ush)(w) >> 8)); \
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/* ===========================================================================
187
* Send a value on a given number of bits.
188
* IN assertion: length <= 16 and value fits in length bits.
191
local void send_bits OF((deflate_state *s, int value, int length));
193
local void send_bits(s, value, length)
195
int value; /* value to send */
196
int length; /* number of bits */
198
Tracevv((stderr," l %2d v %4x ", length, value));
199
Assert(length > 0 && length <= 15, "invalid length");
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s->bits_sent += (ulg)length;
202
/* If not enough room in bi_buf, use (valid) bits from bi_buf and
203
* (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
204
* unused bits in value.
206
if (s->bi_valid > (int)Buf_size - length) {
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s->bi_buf |= (ush)value << s->bi_valid;
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put_short(s, s->bi_buf);
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s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
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s->bi_valid += length - Buf_size;
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s->bi_buf |= (ush)value << s->bi_valid;
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s->bi_valid += length;
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#define send_bits(s, value, length) \
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if (s->bi_valid > (int)Buf_size - len) {\
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s->bi_buf |= (ush)val << s->bi_valid;\
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put_short(s, s->bi_buf);\
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s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
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s->bi_valid += len - Buf_size;\
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s->bi_buf |= (ush)(value) << s->bi_valid;\
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/* the arguments must not have side effects */
236
/* ===========================================================================
237
* Initialize the various 'constant' tables.
239
local void tr_static_init()
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#if defined(GEN_TREES_H) || !defined(STDC)
242
static int static_init_done = 0;
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int n; /* iterates over tree elements */
244
int bits; /* bit counter */
245
int length; /* length value */
246
int code; /* code value */
247
int dist; /* distance index */
248
ush bl_count[MAX_BITS+1];
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/* number of codes at each bit length for an optimal tree */
251
if (static_init_done) return;
253
/* For some embedded targets, global variables are not initialized: */
254
#ifdef NO_INIT_GLOBAL_POINTERS
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static_l_desc.static_tree = static_ltree;
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static_l_desc.extra_bits = extra_lbits;
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static_d_desc.static_tree = static_dtree;
258
static_d_desc.extra_bits = extra_dbits;
259
static_bl_desc.extra_bits = extra_blbits;
262
/* Initialize the mapping length (0..255) -> length code (0..28) */
264
for (code = 0; code < LENGTH_CODES-1; code++) {
265
base_length[code] = length;
266
for (n = 0; n < (1<<extra_lbits[code]); n++) {
267
_length_code[length++] = (uch)code;
270
Assert (length == 256, "tr_static_init: length != 256");
271
/* Note that the length 255 (match length 258) can be represented
272
* in two different ways: code 284 + 5 bits or code 285, so we
273
* overwrite length_code[255] to use the best encoding:
275
_length_code[length-1] = (uch)code;
277
/* Initialize the mapping dist (0..32K) -> dist code (0..29) */
279
for (code = 0 ; code < 16; code++) {
280
base_dist[code] = dist;
281
for (n = 0; n < (1<<extra_dbits[code]); n++) {
282
_dist_code[dist++] = (uch)code;
285
Assert (dist == 256, "tr_static_init: dist != 256");
286
dist >>= 7; /* from now on, all distances are divided by 128 */
287
for ( ; code < D_CODES; code++) {
288
base_dist[code] = dist << 7;
289
for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
290
_dist_code[256 + dist++] = (uch)code;
293
Assert (dist == 256, "tr_static_init: 256+dist != 512");
295
/* Construct the codes of the static literal tree */
296
for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
298
while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
299
while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
300
while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
301
while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
302
/* Codes 286 and 287 do not exist, but we must include them in the
303
* tree construction to get a canonical Huffman tree (longest code
306
gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
308
/* The static distance tree is trivial: */
309
for (n = 0; n < D_CODES; n++) {
310
static_dtree[n].Len = 5;
311
static_dtree[n].Code = bi_reverse((unsigned)n, 5);
313
static_init_done = 1;
318
#endif /* defined(GEN_TREES_H) || !defined(STDC) */
321
/* ===========================================================================
322
* Genererate the file trees.h describing the static trees.
329
# define SEPARATOR(i, last, width) \
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((i) == (last)? "\n};\n\n" : \
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((i) % (width) == (width)-1 ? ",\n" : ", "))
333
void gen_trees_header()
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FILE *header = fopen("trees.h", "w");
338
Assert (header != NULL, "Can't open trees.h");
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"/* header created automatically with -DGEN_TREES_H */\n\n");
342
fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
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for (i = 0; i < L_CODES+2; i++) {
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fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
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static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
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fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
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for (i = 0; i < D_CODES; i++) {
350
fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
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static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
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fprintf(header, "const uch ZLIB_INTERNAL _dist_code[DIST_CODE_LEN] = {\n");
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for (i = 0; i < DIST_CODE_LEN; i++) {
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fprintf(header, "%2u%s", _dist_code[i],
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SEPARATOR(i, DIST_CODE_LEN-1, 20));
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"const uch ZLIB_INTERNAL _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
362
for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
363
fprintf(header, "%2u%s", _length_code[i],
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SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
367
fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
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for (i = 0; i < LENGTH_CODES; i++) {
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fprintf(header, "%1u%s", base_length[i],
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SEPARATOR(i, LENGTH_CODES-1, 20));
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fprintf(header, "local const int base_dist[D_CODES] = {\n");
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for (i = 0; i < D_CODES; i++) {
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fprintf(header, "%5u%s", base_dist[i],
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SEPARATOR(i, D_CODES-1, 10));
381
#endif /* GEN_TREES_H */
383
/* ===========================================================================
384
* Initialize the tree data structures for a new zlib stream.
386
void ZLIB_INTERNAL _tr_init(s)
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s->l_desc.dyn_tree = s->dyn_ltree;
392
s->l_desc.stat_desc = &static_l_desc;
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s->d_desc.dyn_tree = s->dyn_dtree;
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s->d_desc.stat_desc = &static_d_desc;
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s->bl_desc.dyn_tree = s->bl_tree;
398
s->bl_desc.stat_desc = &static_bl_desc;
402
s->last_eob_len = 8; /* enough lookahead for inflate */
404
s->compressed_len = 0L;
408
/* Initialize the first block of the first file: */
412
/* ===========================================================================
413
* Initialize a new block.
415
local void init_block(s)
418
int n; /* iterates over tree elements */
420
/* Initialize the trees. */
421
for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0;
422
for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0;
423
for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
425
s->dyn_ltree[END_BLOCK].Freq = 1;
426
s->opt_len = s->static_len = 0L;
427
s->last_lit = s->matches = 0;
431
/* Index within the heap array of least frequent node in the Huffman tree */
434
/* ===========================================================================
435
* Remove the smallest element from the heap and recreate the heap with
436
* one less element. Updates heap and heap_len.
438
#define pqremove(s, tree, top) \
440
top = s->heap[SMALLEST]; \
441
s->heap[SMALLEST] = s->heap[s->heap_len--]; \
442
pqdownheap(s, tree, SMALLEST); \
445
/* ===========================================================================
446
* Compares to subtrees, using the tree depth as tie breaker when
447
* the subtrees have equal frequency. This minimizes the worst case length.
449
#define smaller(tree, n, m, depth) \
450
(tree[n].Freq < tree[m].Freq || \
451
(tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
453
/* ===========================================================================
454
* Restore the heap property by moving down the tree starting at node k,
455
* exchanging a node with the smallest of its two sons if necessary, stopping
456
* when the heap property is re-established (each father smaller than its
459
local void pqdownheap(s, tree, k)
461
ct_data *tree; /* the tree to restore */
462
int k; /* node to move down */
465
int j = k << 1; /* left son of k */
466
while (j <= s->heap_len) {
467
/* Set j to the smallest of the two sons: */
468
if (j < s->heap_len &&
469
smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
472
/* Exit if v is smaller than both sons */
473
if (smaller(tree, v, s->heap[j], s->depth)) break;
475
/* Exchange v with the smallest son */
476
s->heap[k] = s->heap[j]; k = j;
478
/* And continue down the tree, setting j to the left son of k */
484
/* ===========================================================================
485
* Compute the optimal bit lengths for a tree and update the total bit length
486
* for the current block.
487
* IN assertion: the fields freq and dad are set, heap[heap_max] and
488
* above are the tree nodes sorted by increasing frequency.
489
* OUT assertions: the field len is set to the optimal bit length, the
490
* array bl_count contains the frequencies for each bit length.
491
* The length opt_len is updated; static_len is also updated if stree is
494
local void gen_bitlen(s, desc)
496
tree_desc *desc; /* the tree descriptor */
498
ct_data *tree = desc->dyn_tree;
499
int max_code = desc->max_code;
500
const ct_data *stree = desc->stat_desc->static_tree;
501
const intf *extra = desc->stat_desc->extra_bits;
502
int base = desc->stat_desc->extra_base;
503
int max_length = desc->stat_desc->max_length;
504
int h; /* heap index */
505
int n, m; /* iterate over the tree elements */
506
int bits; /* bit length */
507
int xbits; /* extra bits */
508
ush f; /* frequency */
509
int overflow = 0; /* number of elements with bit length too large */
511
for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
513
/* In a first pass, compute the optimal bit lengths (which may
514
* overflow in the case of the bit length tree).
516
tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
518
for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
520
bits = tree[tree[n].Dad].Len + 1;
521
if (bits > max_length) bits = max_length, overflow++;
522
tree[n].Len = (ush)bits;
523
/* We overwrite tree[n].Dad which is no longer needed */
525
if (n > max_code) continue; /* not a leaf node */
529
if (n >= base) xbits = extra[n-base];
531
s->opt_len += (ulg)f * (bits + xbits);
532
if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
534
if (overflow == 0) return;
536
Trace((stderr,"\nbit length overflow\n"));
537
/* This happens for example on obj2 and pic of the Calgary corpus */
539
/* Find the first bit length which could increase: */
542
while (s->bl_count[bits] == 0) bits--;
543
s->bl_count[bits]--; /* move one leaf down the tree */
544
s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
545
s->bl_count[max_length]--;
546
/* The brother of the overflow item also moves one step up,
547
* but this does not affect bl_count[max_length]
550
} while (overflow > 0);
552
/* Now recompute all bit lengths, scanning in increasing frequency.
553
* h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
554
* lengths instead of fixing only the wrong ones. This idea is taken
555
* from 'ar' written by Haruhiko Okumura.)
557
for (bits = max_length; bits != 0; bits--) {
558
n = s->bl_count[bits];
561
if (m > max_code) continue;
562
if ((unsigned) tree[m].Len != (unsigned) bits) {
563
Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
564
s->opt_len += ((long)bits - (long)tree[m].Len)
566
tree[m].Len = (ush)bits;
573
/* ===========================================================================
574
* Generate the codes for a given tree and bit counts (which need not be
576
* IN assertion: the array bl_count contains the bit length statistics for
577
* the given tree and the field len is set for all tree elements.
578
* OUT assertion: the field code is set for all tree elements of non
581
local void gen_codes (tree, max_code, bl_count)
582
ct_data *tree; /* the tree to decorate */
583
int max_code; /* largest code with non zero frequency */
584
ushf *bl_count; /* number of codes at each bit length */
586
ush next_code[MAX_BITS+1]; /* next code value for each bit length */
587
ush code = 0; /* running code value */
588
int bits; /* bit index */
589
int n; /* code index */
591
/* The distribution counts are first used to generate the code values
592
* without bit reversal.
594
for (bits = 1; bits <= MAX_BITS; bits++) {
595
next_code[bits] = code = (code + bl_count[bits-1]) << 1;
597
/* Check that the bit counts in bl_count are consistent. The last code
600
Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
601
"inconsistent bit counts");
602
Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
604
for (n = 0; n <= max_code; n++) {
605
int len = tree[n].Len;
606
if (len == 0) continue;
607
/* Now reverse the bits */
608
tree[n].Code = bi_reverse(next_code[len]++, len);
610
Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
611
n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
615
/* ===========================================================================
616
* Construct one Huffman tree and assigns the code bit strings and lengths.
617
* Update the total bit length for the current block.
618
* IN assertion: the field freq is set for all tree elements.
619
* OUT assertions: the fields len and code are set to the optimal bit length
620
* and corresponding code. The length opt_len is updated; static_len is
621
* also updated if stree is not null. The field max_code is set.
623
local void build_tree(s, desc)
625
tree_desc *desc; /* the tree descriptor */
627
ct_data *tree = desc->dyn_tree;
628
const ct_data *stree = desc->stat_desc->static_tree;
629
int elems = desc->stat_desc->elems;
630
int n, m; /* iterate over heap elements */
631
int max_code = -1; /* largest code with non zero frequency */
632
int node; /* new node being created */
634
/* Construct the initial heap, with least frequent element in
635
* heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
636
* heap[0] is not used.
638
s->heap_len = 0, s->heap_max = HEAP_SIZE;
640
for (n = 0; n < elems; n++) {
641
if (tree[n].Freq != 0) {
642
s->heap[++(s->heap_len)] = max_code = n;
649
/* The pkzip format requires that at least one distance code exists,
650
* and that at least one bit should be sent even if there is only one
651
* possible code. So to avoid special checks later on we force at least
652
* two codes of non zero frequency.
654
while (s->heap_len < 2) {
655
node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
658
s->opt_len--; if (stree) s->static_len -= stree[node].Len;
659
/* node is 0 or 1 so it does not have extra bits */
661
desc->max_code = max_code;
663
/* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
664
* establish sub-heaps of increasing lengths:
666
for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
668
/* Construct the Huffman tree by repeatedly combining the least two
671
node = elems; /* next internal node of the tree */
673
pqremove(s, tree, n); /* n = node of least frequency */
674
m = s->heap[SMALLEST]; /* m = node of next least frequency */
676
s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
677
s->heap[--(s->heap_max)] = m;
679
/* Create a new node father of n and m */
680
tree[node].Freq = tree[n].Freq + tree[m].Freq;
681
s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
682
s->depth[n] : s->depth[m]) + 1);
683
tree[n].Dad = tree[m].Dad = (ush)node;
685
if (tree == s->bl_tree) {
686
fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
687
node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
690
/* and insert the new node in the heap */
691
s->heap[SMALLEST] = node++;
692
pqdownheap(s, tree, SMALLEST);
694
} while (s->heap_len >= 2);
696
s->heap[--(s->heap_max)] = s->heap[SMALLEST];
698
/* At this point, the fields freq and dad are set. We can now
699
* generate the bit lengths.
701
gen_bitlen(s, (tree_desc *)desc);
703
/* The field len is now set, we can generate the bit codes */
704
gen_codes ((ct_data *)tree, max_code, s->bl_count);
707
/* ===========================================================================
708
* Scan a literal or distance tree to determine the frequencies of the codes
709
* in the bit length tree.
711
local void scan_tree (s, tree, max_code)
713
ct_data *tree; /* the tree to be scanned */
714
int max_code; /* and its largest code of non zero frequency */
716
int n; /* iterates over all tree elements */
717
int prevlen = -1; /* last emitted length */
718
int curlen; /* length of current code */
719
int nextlen = tree[0].Len; /* length of next code */
720
int count = 0; /* repeat count of the current code */
721
int max_count = 7; /* max repeat count */
722
int min_count = 4; /* min repeat count */
724
if (nextlen == 0) max_count = 138, min_count = 3;
725
tree[max_code+1].Len = (ush)0xffff; /* guard */
727
for (n = 0; n <= max_code; n++) {
728
curlen = nextlen; nextlen = tree[n+1].Len;
729
if (++count < max_count && curlen == nextlen) {
731
} else if (count < min_count) {
732
s->bl_tree[curlen].Freq += count;
733
} else if (curlen != 0) {
734
if (curlen != prevlen) s->bl_tree[curlen].Freq++;
735
s->bl_tree[REP_3_6].Freq++;
736
} else if (count <= 10) {
737
s->bl_tree[REPZ_3_10].Freq++;
739
s->bl_tree[REPZ_11_138].Freq++;
741
count = 0; prevlen = curlen;
743
max_count = 138, min_count = 3;
744
} else if (curlen == nextlen) {
745
max_count = 6, min_count = 3;
747
max_count = 7, min_count = 4;
752
/* ===========================================================================
753
* Send a literal or distance tree in compressed form, using the codes in
756
local void send_tree (s, tree, max_code)
758
ct_data *tree; /* the tree to be scanned */
759
int max_code; /* and its largest code of non zero frequency */
761
int n; /* iterates over all tree elements */
762
int prevlen = -1; /* last emitted length */
763
int curlen; /* length of current code */
764
int nextlen = tree[0].Len; /* length of next code */
765
int count = 0; /* repeat count of the current code */
766
int max_count = 7; /* max repeat count */
767
int min_count = 4; /* min repeat count */
769
/* tree[max_code+1].Len = -1; */ /* guard already set */
770
if (nextlen == 0) max_count = 138, min_count = 3;
772
for (n = 0; n <= max_code; n++) {
773
curlen = nextlen; nextlen = tree[n+1].Len;
774
if (++count < max_count && curlen == nextlen) {
776
} else if (count < min_count) {
777
do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
779
} else if (curlen != 0) {
780
if (curlen != prevlen) {
781
send_code(s, curlen, s->bl_tree); count--;
783
Assert(count >= 3 && count <= 6, " 3_6?");
784
send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
786
} else if (count <= 10) {
787
send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
790
send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
792
count = 0; prevlen = curlen;
794
max_count = 138, min_count = 3;
795
} else if (curlen == nextlen) {
796
max_count = 6, min_count = 3;
798
max_count = 7, min_count = 4;
803
/* ===========================================================================
804
* Construct the Huffman tree for the bit lengths and return the index in
805
* bl_order of the last bit length code to send.
807
local int build_bl_tree(s)
810
int max_blindex; /* index of last bit length code of non zero freq */
812
/* Determine the bit length frequencies for literal and distance trees */
813
scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
814
scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
816
/* Build the bit length tree: */
817
build_tree(s, (tree_desc *)(&(s->bl_desc)));
818
/* opt_len now includes the length of the tree representations, except
819
* the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
822
/* Determine the number of bit length codes to send. The pkzip format
823
* requires that at least 4 bit length codes be sent. (appnote.txt says
824
* 3 but the actual value used is 4.)
826
for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
827
if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
829
/* Update opt_len to include the bit length tree and counts */
830
s->opt_len += 3*(max_blindex+1) + 5+5+4;
831
Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
832
s->opt_len, s->static_len));
837
/* ===========================================================================
838
* Send the header for a block using dynamic Huffman trees: the counts, the
839
* lengths of the bit length codes, the literal tree and the distance tree.
840
* IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
842
local void send_all_trees(s, lcodes, dcodes, blcodes)
844
int lcodes, dcodes, blcodes; /* number of codes for each tree */
846
int rank; /* index in bl_order */
848
Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
849
Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
851
Tracev((stderr, "\nbl counts: "));
852
send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
853
send_bits(s, dcodes-1, 5);
854
send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */
855
for (rank = 0; rank < blcodes; rank++) {
856
Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
857
send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
859
Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
861
send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
862
Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
864
send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
865
Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
868
/* ===========================================================================
869
* Send a stored block
871
void ZLIB_INTERNAL _tr_stored_block(s, buf, stored_len, last)
873
charf *buf; /* input block */
874
ulg stored_len; /* length of input block */
875
int last; /* one if this is the last block for a file */
877
send_bits(s, (STORED_BLOCK<<1)+last, 3); /* send block type */
879
s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
880
s->compressed_len += (stored_len + 4) << 3;
882
copy_block(s, buf, (unsigned)stored_len, 1); /* with header */
885
/* ===========================================================================
886
* Send one empty static block to give enough lookahead for inflate.
887
* This takes 10 bits, of which 7 may remain in the bit buffer.
888
* The current inflate code requires 9 bits of lookahead. If the
889
* last two codes for the previous block (real code plus EOB) were coded
890
* on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode
891
* the last real code. In this case we send two empty static blocks instead
892
* of one. (There are no problems if the previous block is stored or fixed.)
893
* To simplify the code, we assume the worst case of last real code encoded
896
void ZLIB_INTERNAL _tr_align(s)
899
send_bits(s, STATIC_TREES<<1, 3);
900
send_code(s, END_BLOCK, static_ltree);
902
s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
905
/* Of the 10 bits for the empty block, we have already sent
906
* (10 - bi_valid) bits. The lookahead for the last real code (before
907
* the EOB of the previous block) was thus at least one plus the length
908
* of the EOB plus what we have just sent of the empty static block.
910
if (1 + s->last_eob_len + 10 - s->bi_valid < 9) {
911
send_bits(s, STATIC_TREES<<1, 3);
912
send_code(s, END_BLOCK, static_ltree);
914
s->compressed_len += 10L;
921
/* ===========================================================================
922
* Determine the best encoding for the current block: dynamic trees, static
923
* trees or store, and output the encoded block to the zip file.
925
void ZLIB_INTERNAL _tr_flush_block(s, buf, stored_len, last)
927
charf *buf; /* input block, or NULL if too old */
928
ulg stored_len; /* length of input block */
929
int last; /* one if this is the last block for a file */
931
ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
932
int max_blindex = 0; /* index of last bit length code of non zero freq */
934
/* Build the Huffman trees unless a stored block is forced */
937
/* Check if the file is binary or text */
938
if (s->strm->data_type == Z_UNKNOWN)
939
s->strm->data_type = detect_data_type(s);
941
/* Construct the literal and distance trees */
942
build_tree(s, (tree_desc *)(&(s->l_desc)));
943
Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
946
build_tree(s, (tree_desc *)(&(s->d_desc)));
947
Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
949
/* At this point, opt_len and static_len are the total bit lengths of
950
* the compressed block data, excluding the tree representations.
953
/* Build the bit length tree for the above two trees, and get the index
954
* in bl_order of the last bit length code to send.
956
max_blindex = build_bl_tree(s);
958
/* Determine the best encoding. Compute the block lengths in bytes. */
959
opt_lenb = (s->opt_len+3+7)>>3;
960
static_lenb = (s->static_len+3+7)>>3;
962
Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
963
opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
966
if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
969
Assert(buf != (char*)0, "lost buf");
970
opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
974
if (buf != (char*)0) { /* force stored block */
976
if (stored_len+4 <= opt_lenb && buf != (char*)0) {
977
/* 4: two words for the lengths */
979
/* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
980
* Otherwise we can't have processed more than WSIZE input bytes since
981
* the last block flush, because compression would have been
982
* successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
983
* transform a block into a stored block.
985
_tr_stored_block(s, buf, stored_len, last);
988
} else if (static_lenb >= 0) { /* force static trees */
990
} else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
992
send_bits(s, (STATIC_TREES<<1)+last, 3);
993
compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree);
995
s->compressed_len += 3 + s->static_len;
998
send_bits(s, (DYN_TREES<<1)+last, 3);
999
send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
1001
compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree);
1003
s->compressed_len += 3 + s->opt_len;
1006
Assert (s->compressed_len == s->bits_sent, "bad compressed size");
1007
/* The above check is made mod 2^32, for files larger than 512 MB
1008
* and uLong implemented on 32 bits.
1015
s->compressed_len += 7; /* align on byte boundary */
1018
Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
1019
s->compressed_len-7*last));
1022
/* ===========================================================================
1023
* Save the match info and tally the frequency counts. Return true if
1024
* the current block must be flushed.
1026
int ZLIB_INTERNAL _tr_tally (s, dist, lc)
1028
unsigned dist; /* distance of matched string */
1029
unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */
1031
s->d_buf[s->last_lit] = (ush)dist;
1032
s->l_buf[s->last_lit++] = (uch)lc;
1034
/* lc is the unmatched char */
1035
s->dyn_ltree[lc].Freq++;
1038
/* Here, lc is the match length - MIN_MATCH */
1039
dist--; /* dist = match distance - 1 */
1040
Assert((ush)dist < (ush)MAX_DIST(s) &&
1041
(ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
1042
(ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match");
1044
s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
1045
s->dyn_dtree[d_code(dist)].Freq++;
1048
#ifdef TRUNCATE_BLOCK
1049
/* Try to guess if it is profitable to stop the current block here */
1050
if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
1051
/* Compute an upper bound for the compressed length */
1052
ulg out_length = (ulg)s->last_lit*8L;
1053
ulg in_length = (ulg)((long)s->strstart - s->block_start);
1055
for (dcode = 0; dcode < D_CODES; dcode++) {
1056
out_length += (ulg)s->dyn_dtree[dcode].Freq *
1057
(5L+extra_dbits[dcode]);
1060
Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
1061
s->last_lit, in_length, out_length,
1062
100L - out_length*100L/in_length));
1063
if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
1066
return (s->last_lit == s->lit_bufsize-1);
1067
/* We avoid equality with lit_bufsize because of wraparound at 64K
1068
* on 16 bit machines and because stored blocks are restricted to
1073
/* ===========================================================================
1074
* Send the block data compressed using the given Huffman trees
1076
local void compress_block(s, ltree, dtree)
1078
ct_data *ltree; /* literal tree */
1079
ct_data *dtree; /* distance tree */
1081
unsigned dist; /* distance of matched string */
1082
int lc; /* match length or unmatched char (if dist == 0) */
1083
unsigned lx = 0; /* running index in l_buf */
1084
unsigned code; /* the code to send */
1085
int extra; /* number of extra bits to send */
1087
if (s->last_lit != 0) do {
1088
dist = s->d_buf[lx];
1089
lc = s->l_buf[lx++];
1091
send_code(s, lc, ltree); /* send a literal byte */
1092
Tracecv(isgraph(lc), (stderr," '%c' ", lc));
1094
/* Here, lc is the match length - MIN_MATCH */
1095
code = _length_code[lc];
1096
send_code(s, code+LITERALS+1, ltree); /* send the length code */
1097
extra = extra_lbits[code];
1099
lc -= base_length[code];
1100
send_bits(s, lc, extra); /* send the extra length bits */
1102
dist--; /* dist is now the match distance - 1 */
1103
code = d_code(dist);
1104
Assert (code < D_CODES, "bad d_code");
1106
send_code(s, code, dtree); /* send the distance code */
1107
extra = extra_dbits[code];
1109
dist -= base_dist[code];
1110
send_bits(s, dist, extra); /* send the extra distance bits */
1112
} /* literal or match pair ? */
1114
/* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
1115
Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
1116
"pendingBuf overflow");
1118
} while (lx < s->last_lit);
1120
send_code(s, END_BLOCK, ltree);
1121
s->last_eob_len = ltree[END_BLOCK].Len;
1124
/* ===========================================================================
1125
* Check if the data type is TEXT or BINARY, using the following algorithm:
1126
* - TEXT if the two conditions below are satisfied:
1127
* a) There are no non-portable control characters belonging to the
1128
* "black list" (0..6, 14..25, 28..31).
1129
* b) There is at least one printable character belonging to the
1130
* "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
1131
* - BINARY otherwise.
1132
* - The following partially-portable control characters form a
1133
* "gray list" that is ignored in this detection algorithm:
1134
* (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).
1135
* IN assertion: the fields Freq of dyn_ltree are set.
1137
local int detect_data_type(s)
1140
/* black_mask is the bit mask of black-listed bytes
1141
* set bits 0..6, 14..25, and 28..31
1142
* 0xf3ffc07f = binary 11110011111111111100000001111111
1144
unsigned long black_mask = 0xf3ffc07fUL;
1147
/* Check for non-textual ("black-listed") bytes. */
1148
for (n = 0; n <= 31; n++, black_mask >>= 1)
1149
if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0))
1152
/* Check for textual ("white-listed") bytes. */
1153
if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0
1154
|| s->dyn_ltree[13].Freq != 0)
1156
for (n = 32; n < LITERALS; n++)
1157
if (s->dyn_ltree[n].Freq != 0)
1160
/* There are no "black-listed" or "white-listed" bytes:
1161
* this stream either is empty or has tolerated ("gray-listed") bytes only.
1166
/* ===========================================================================
1167
* Reverse the first len bits of a code, using straightforward code (a faster
1168
* method would use a table)
1169
* IN assertion: 1 <= len <= 15
1171
local unsigned bi_reverse(code, len)
1172
unsigned code; /* the value to invert */
1173
int len; /* its bit length */
1175
register unsigned res = 0;
1178
code >>= 1, res <<= 1;
1179
} while (--len > 0);
1183
/* ===========================================================================
1184
* Flush the bit buffer, keeping at most 7 bits in it.
1186
local void bi_flush(s)
1189
if (s->bi_valid == 16) {
1190
put_short(s, s->bi_buf);
1193
} else if (s->bi_valid >= 8) {
1194
put_byte(s, (Byte)s->bi_buf);
1200
/* ===========================================================================
1201
* Flush the bit buffer and align the output on a byte boundary
1203
local void bi_windup(s)
1206
if (s->bi_valid > 8) {
1207
put_short(s, s->bi_buf);
1208
} else if (s->bi_valid > 0) {
1209
put_byte(s, (Byte)s->bi_buf);
1214
s->bits_sent = (s->bits_sent+7) & ~7;
1218
/* ===========================================================================
1219
* Copy a stored block, storing first the length and its
1220
* one's complement if requested.
1222
local void copy_block(s, buf, len, header)
1224
charf *buf; /* the input data */
1225
unsigned len; /* its length */
1226
int header; /* true if block header must be written */
1228
bi_windup(s); /* align on byte boundary */
1229
s->last_eob_len = 8; /* enough lookahead for inflate */
1232
put_short(s, (ush)len);
1233
put_short(s, (ush)~len);
1235
s->bits_sent += 2*16;
1239
s->bits_sent += (ulg)len<<3;
1242
put_byte(s, *buf++);