1 /* trees.c -- output deflated data using Huffman coding
3 Copyright (C) 1997-1999, 2009-2011 Free Software Foundation, Inc.
4 Copyright (C) 1992-1993 Jean-loup Gailly
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3, or (at your option)
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software Foundation,
18 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
23 * Encode various sets of source values using variable-length
28 * The PKZIP "deflation" process uses several Huffman trees. The more
29 * common source values are represented by shorter bit sequences.
31 * Each code tree is stored in the ZIP file in a compressed form
32 * which is itself a Huffman encoding of the lengths of
33 * all the code strings (in ascending order by source values).
34 * The actual code strings are reconstructed from the lengths in
35 * the UNZIP process, as described in the "application note"
36 * (APPNOTE.TXT) distributed as part of PKWARE's PKZIP program.
41 * Data Compression: Techniques and Applications, pp. 53-55.
42 * Lifetime Learning Publications, 1985. ISBN 0-534-03418-7.
45 * Data Compression: Methods and Theory, pp. 49-50.
46 * Computer Science Press, 1988. ISBN 0-7167-8156-5.
50 * Addison-Wesley, 1983. ISBN 0-201-06672-6.
54 * void ct_init (ush *attr, int *methodp)
55 * Allocate the match buffer, initialize the various tables and save
56 * the location of the internal file attribute (ascii/binary) and
57 * method (DEFLATE/STORE)
59 * void ct_tally (int dist, int lc);
60 * Save the match info and tally the frequency counts.
62 * off_t flush_block (char *buf, ulg stored_len, int eof)
63 * Determine the best encoding for the current block: dynamic trees,
64 * static trees or store, and output the encoded block to the zip
65 * file. Returns the total compressed length for the file so far.
75 /* ===========================================================================
80 /* All codes must not exceed MAX_BITS bits */
83 /* Bit length codes must not exceed MAX_BL_BITS bits */
85 #define LENGTH_CODES 29
86 /* number of length codes, not counting the special END_BLOCK code */
89 /* number of literal bytes 0..255 */
92 /* end of block literal code */
94 #define L_CODES (LITERALS+1+LENGTH_CODES)
95 /* number of Literal or Length codes, including the END_BLOCK code */
98 /* number of distance codes */
101 /* number of codes used to transfer the bit lengths */
104 local
int near extra_lbits
[LENGTH_CODES
] /* extra bits for each length code */
105 = {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};
107 local
int near extra_dbits
[D_CODES
] /* extra bits for each distance code */
108 = {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};
110 local
int near extra_blbits
[BL_CODES
]/* extra bits for each bit length code */
111 = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
113 #define STORED_BLOCK 0
114 #define STATIC_TREES 1
116 /* The three kinds of block type */
120 # define LIT_BUFSIZE 0x2000
123 # define LIT_BUFSIZE 0x4000
125 # define LIT_BUFSIZE 0x8000
130 # define DIST_BUFSIZE LIT_BUFSIZE
132 /* Sizes of match buffers for literals/lengths and distances. There are
133 * 4 reasons for limiting LIT_BUFSIZE to 64K:
134 * - frequencies can be kept in 16 bit counters
135 * - if compression is not successful for the first block, all input data is
136 * still in the window so we can still emit a stored block even when input
137 * comes from standard input. (This can also be done for all blocks if
138 * LIT_BUFSIZE is not greater than 32K.)
139 * - if compression is not successful for a file smaller than 64K, we can
140 * even emit a stored file instead of a stored block (saving 5 bytes).
141 * - creating new Huffman trees less frequently may not provide fast
142 * adaptation to changes in the input data statistics. (Take for
143 * example a binary file with poorly compressible code followed by
144 * a highly compressible string table.) Smaller buffer sizes give
145 * fast adaptation but have of course the overhead of transmitting trees
147 * - I can't count above 4
148 * The current code is general and allows DIST_BUFSIZE < LIT_BUFSIZE (to save
149 * memory at the expense of compression). Some optimizations would be possible
150 * if we rely on DIST_BUFSIZE == LIT_BUFSIZE.
152 #if LIT_BUFSIZE > INBUFSIZ
153 error cannot overlay l_buf
and inbuf
157 /* repeat previous bit length 3-6 times (2 bits of repeat count) */
160 /* repeat a zero length 3-10 times (3 bits of repeat count) */
162 #define REPZ_11_138 18
163 /* repeat a zero length 11-138 times (7 bits of repeat count) */
165 /* ===========================================================================
169 /* Data structure describing a single value and its code string. */
170 typedef struct ct_data
{
172 ush freq
; /* frequency count */
173 ush code
; /* bit string */
176 ush dad
; /* father node in Huffman tree */
177 ush len
; /* length of bit string */
186 #define HEAP_SIZE (2*L_CODES+1)
187 /* maximum heap size */
189 local ct_data near dyn_ltree
[HEAP_SIZE
]; /* literal and length tree */
190 local ct_data near dyn_dtree
[2*D_CODES
+1]; /* distance tree */
192 local ct_data near static_ltree
[L_CODES
+2];
193 /* The static literal tree. Since the bit lengths are imposed, there is no
194 * need for the L_CODES extra codes used during heap construction. However
195 * The codes 286 and 287 are needed to build a canonical tree (see ct_init
199 local ct_data near static_dtree
[D_CODES
];
200 /* The static distance tree. (Actually a trivial tree since all codes use
204 local ct_data near bl_tree
[2*BL_CODES
+1];
205 /* Huffman tree for the bit lengths */
207 typedef struct tree_desc
{
208 ct_data near
*dyn_tree
; /* the dynamic tree */
209 ct_data near
*static_tree
; /* corresponding static tree or NULL */
210 int near
*extra_bits
; /* extra bits for each code or NULL */
211 int extra_base
; /* base index for extra_bits */
212 int elems
; /* max number of elements in the tree */
213 int max_length
; /* max bit length for the codes */
214 int max_code
; /* largest code with non zero frequency */
217 local tree_desc near l_desc
=
218 {dyn_ltree
, static_ltree
, extra_lbits
, LITERALS
+1, L_CODES
, MAX_BITS
, 0};
220 local tree_desc near d_desc
=
221 {dyn_dtree
, static_dtree
, extra_dbits
, 0, D_CODES
, MAX_BITS
, 0};
223 local tree_desc near bl_desc
=
224 {bl_tree
, (ct_data near
*)0, extra_blbits
, 0, BL_CODES
, MAX_BL_BITS
, 0};
227 local ush near bl_count
[MAX_BITS
+1];
228 /* number of codes at each bit length for an optimal tree */
230 local uch near bl_order
[BL_CODES
]
231 = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
232 /* The lengths of the bit length codes are sent in order of decreasing
233 * probability, to avoid transmitting the lengths for unused bit length codes.
236 local
int near heap
[2*L_CODES
+1]; /* heap used to build the Huffman trees */
237 local
int heap_len
; /* number of elements in the heap */
238 local
int heap_max
; /* element of largest frequency */
239 /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
240 * The same heap array is used to build all trees.
243 local uch near depth
[2*L_CODES
+1];
244 /* Depth of each subtree used as tie breaker for trees of equal frequency */
246 local uch length_code
[MAX_MATCH
-MIN_MATCH
+1];
247 /* length code for each normalized match length (0 == MIN_MATCH) */
249 local uch dist_code
[512];
250 /* distance codes. The first 256 values correspond to the distances
251 * 3 .. 258, the last 256 values correspond to the top 8 bits of
252 * the 15 bit distances.
255 local
int near base_length
[LENGTH_CODES
];
256 /* First normalized length for each code (0 = MIN_MATCH) */
258 local
int near base_dist
[D_CODES
];
259 /* First normalized distance for each code (0 = distance of 1) */
262 /* DECLARE(uch, l_buf, LIT_BUFSIZE); buffer for literals or lengths */
264 /* DECLARE(ush, d_buf, DIST_BUFSIZE); buffer for distances */
266 local uch near flag_buf
[(LIT_BUFSIZE
/8)];
267 /* flag_buf is a bit array distinguishing literals from lengths in
268 * l_buf, thus indicating the presence or absence of a distance.
271 local
unsigned last_lit
; /* running index in l_buf */
272 local
unsigned last_dist
; /* running index in d_buf */
273 local
unsigned last_flags
; /* running index in flag_buf */
274 local uch flags
; /* current flags not yet saved in flag_buf */
275 local uch flag_bit
; /* current bit used in flags */
276 /* bits are filled in flags starting at bit 0 (least significant).
277 * Note: these flags are overkill in the current code since we don't
278 * take advantage of DIST_BUFSIZE == LIT_BUFSIZE.
281 local ulg opt_len
; /* bit length of current block with optimal trees */
282 local ulg static_len
; /* bit length of current block with static trees */
284 local off_t compressed_len
; /* total bit length of compressed file */
286 local off_t input_len
; /* total byte length of input file */
287 /* input_len is for debugging only since we can get it by other means. */
289 ush
*file_type
; /* pointer to UNKNOWN, BINARY or ASCII */
290 int *file_method
; /* pointer to DEFLATE or STORE */
293 extern off_t bits_sent
; /* bit length of the compressed data */
296 extern long block_start
; /* window offset of current block */
297 extern unsigned near strstart
; /* window offset of current string */
299 /* ===========================================================================
300 * Local (static) routines in this file.
303 local
void init_block
OF((void));
304 local
void pqdownheap
OF((ct_data near
*tree
, int k
));
305 local
void gen_bitlen
OF((tree_desc near
*desc
));
306 local
void gen_codes
OF((ct_data near
*tree
, int max_code
));
307 local
void build_tree
OF((tree_desc near
*desc
));
308 local
void scan_tree
OF((ct_data near
*tree
, int max_code
));
309 local
void send_tree
OF((ct_data near
*tree
, int max_code
));
310 local
int build_bl_tree
OF((void));
311 local
void send_all_trees
OF((int lcodes
, int dcodes
, int blcodes
));
312 local
void compress_block
OF((ct_data near
*ltree
, ct_data near
*dtree
));
313 local
void set_file_type
OF((void));
317 # define send_code(c, tree) send_bits(tree[c].Code, tree[c].Len)
318 /* Send a code of the given tree. c and tree must not have side effects */
321 # define send_code(c, tree) \
322 { if (verbose>1) fprintf(stderr,"\ncd %3d ",(c)); \
323 send_bits(tree[c].Code, tree[c].Len); }
326 #define d_code(dist) \
327 ((dist) < 256 ? dist_code[dist] : dist_code[256+((dist)>>7)])
328 /* Mapping from a distance to a distance code. dist is the distance - 1 and
329 * must not have side effects. dist_code[256] and dist_code[257] are never
333 #define MAX(a,b) (a >= b ? a : b)
334 /* the arguments must not have side effects */
336 /* ===========================================================================
337 * Allocate the match buffer, initialize the various tables and save the
338 * location of the internal file attribute (ascii/binary) and method
341 void ct_init(attr
, methodp
)
342 ush
*attr
; /* pointer to internal file attribute */
343 int *methodp
; /* pointer to compression method */
345 int n
; /* iterates over tree elements */
346 int bits
; /* bit counter */
347 int length
; /* length value */
348 int code
; /* code value */
349 int dist
; /* distance index */
352 file_method
= methodp
;
353 compressed_len
= input_len
= 0L;
355 if (static_dtree
[0].Len
!= 0) return; /* ct_init already called */
357 /* Initialize the mapping length (0..255) -> length code (0..28) */
359 for (code
= 0; code
< LENGTH_CODES
-1; code
++) {
360 base_length
[code
] = length
;
361 for (n
= 0; n
< (1<<extra_lbits
[code
]); n
++) {
362 length_code
[length
++] = (uch
)code
;
365 Assert (length
== 256, "ct_init: length != 256");
366 /* Note that the length 255 (match length 258) can be represented
367 * in two different ways: code 284 + 5 bits or code 285, so we
368 * overwrite length_code[255] to use the best encoding:
370 length_code
[length
-1] = (uch
)code
;
372 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
374 for (code
= 0 ; code
< 16; code
++) {
375 base_dist
[code
] = dist
;
376 for (n
= 0; n
< (1<<extra_dbits
[code
]); n
++) {
377 dist_code
[dist
++] = (uch
)code
;
380 Assert (dist
== 256, "ct_init: dist != 256");
381 dist
>>= 7; /* from now on, all distances are divided by 128 */
382 for ( ; code
< D_CODES
; code
++) {
383 base_dist
[code
] = dist
<< 7;
384 for (n
= 0; n
< (1<<(extra_dbits
[code
]-7)); n
++) {
385 dist_code
[256 + dist
++] = (uch
)code
;
388 Assert (dist
== 256, "ct_init: 256+dist != 512");
390 /* Construct the codes of the static literal tree */
391 for (bits
= 0; bits
<= MAX_BITS
; bits
++) bl_count
[bits
] = 0;
393 while (n
<= 143) static_ltree
[n
++].Len
= 8, bl_count
[8]++;
394 while (n
<= 255) static_ltree
[n
++].Len
= 9, bl_count
[9]++;
395 while (n
<= 279) static_ltree
[n
++].Len
= 7, bl_count
[7]++;
396 while (n
<= 287) static_ltree
[n
++].Len
= 8, bl_count
[8]++;
397 /* Codes 286 and 287 do not exist, but we must include them in the
398 * tree construction to get a canonical Huffman tree (longest code
401 gen_codes((ct_data near
*)static_ltree
, L_CODES
+1);
403 /* The static distance tree is trivial: */
404 for (n
= 0; n
< D_CODES
; n
++) {
405 static_dtree
[n
].Len
= 5;
406 static_dtree
[n
].Code
= bi_reverse(n
, 5);
409 /* Initialize the first block of the first file: */
413 /* ===========================================================================
414 * Initialize a new block.
416 local
void init_block()
418 int n
; /* iterates over tree elements */
420 /* Initialize the trees. */
421 for (n
= 0; n
< L_CODES
; n
++) dyn_ltree
[n
].Freq
= 0;
422 for (n
= 0; n
< D_CODES
; n
++) dyn_dtree
[n
].Freq
= 0;
423 for (n
= 0; n
< BL_CODES
; n
++) bl_tree
[n
].Freq
= 0;
425 dyn_ltree
[END_BLOCK
].Freq
= 1;
426 opt_len
= static_len
= 0L;
427 last_lit
= last_dist
= last_flags
= 0;
428 flags
= 0; flag_bit
= 1;
432 /* Index within the heap array of least frequent node in the Huffman tree */
435 /* ===========================================================================
436 * Remove the smallest element from the heap and recreate the heap with
437 * one less element. Updates heap and heap_len.
439 #define pqremove(tree, top) \
441 top = heap[SMALLEST]; \
442 heap[SMALLEST] = heap[heap_len--]; \
443 pqdownheap(tree, SMALLEST); \
446 /* ===========================================================================
447 * Compares to subtrees, using the tree depth as tie breaker when
448 * the subtrees have equal frequency. This minimizes the worst case length.
450 #define smaller(tree, n, m) \
451 (tree[n].Freq < tree[m].Freq || \
452 (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
454 /* ===========================================================================
455 * Restore the heap property by moving down the tree starting at node k,
456 * exchanging a node with the smallest of its two sons if necessary, stopping
457 * when the heap property is re-established (each father smaller than its
460 local
void pqdownheap(tree
, k
)
461 ct_data near
*tree
; /* the tree to restore */
462 int k
; /* node to move down */
465 int j
= k
<< 1; /* left son of k */
466 while (j
<= heap_len
) {
467 /* Set j to the smallest of the two sons: */
468 if (j
< heap_len
&& smaller(tree
, heap
[j
+1], heap
[j
])) j
++;
470 /* Exit if v is smaller than both sons */
471 if (smaller(tree
, v
, heap
[j
])) break;
473 /* Exchange v with the smallest son */
474 heap
[k
] = heap
[j
]; k
= j
;
476 /* And continue down the tree, setting j to the left son of k */
482 /* ===========================================================================
483 * Compute the optimal bit lengths for a tree and update the total bit length
484 * for the current block.
485 * IN assertion: the fields freq and dad are set, heap[heap_max] and
486 * above are the tree nodes sorted by increasing frequency.
487 * OUT assertions: the field len is set to the optimal bit length, the
488 * array bl_count contains the frequencies for each bit length.
489 * The length opt_len is updated; static_len is also updated if stree is
492 local
void gen_bitlen(desc
)
493 tree_desc near
*desc
; /* the tree descriptor */
495 ct_data near
*tree
= desc
->dyn_tree
;
496 int near
*extra
= desc
->extra_bits
;
497 int base
= desc
->extra_base
;
498 int max_code
= desc
->max_code
;
499 int max_length
= desc
->max_length
;
500 ct_data near
*stree
= desc
->static_tree
;
501 int h
; /* heap index */
502 int n
, m
; /* iterate over the tree elements */
503 int bits
; /* bit length */
504 int xbits
; /* extra bits */
505 ush f
; /* frequency */
506 int overflow
= 0; /* number of elements with bit length too large */
508 for (bits
= 0; bits
<= MAX_BITS
; bits
++) bl_count
[bits
] = 0;
510 /* In a first pass, compute the optimal bit lengths (which may
511 * overflow in the case of the bit length tree).
513 tree
[heap
[heap_max
]].Len
= 0; /* root of the heap */
515 for (h
= heap_max
+1; h
< HEAP_SIZE
; h
++) {
517 bits
= tree
[tree
[n
].Dad
].Len
+ 1;
518 if (bits
> max_length
) bits
= max_length
, overflow
++;
519 tree
[n
].Len
= (ush
)bits
;
520 /* We overwrite tree[n].Dad which is no longer needed */
522 if (n
> max_code
) continue; /* not a leaf node */
526 if (n
>= base
) xbits
= extra
[n
-base
];
528 opt_len
+= (ulg
)f
* (bits
+ xbits
);
529 if (stree
) static_len
+= (ulg
)f
* (stree
[n
].Len
+ xbits
);
531 if (overflow
== 0) return;
533 Trace((stderr
,"\nbit length overflow\n"));
534 /* This happens for example on obj2 and pic of the Calgary corpus */
536 /* Find the first bit length which could increase: */
539 while (bl_count
[bits
] == 0) bits
--;
540 bl_count
[bits
]--; /* move one leaf down the tree */
541 bl_count
[bits
+1] += 2; /* move one overflow item as its brother */
542 bl_count
[max_length
]--;
543 /* The brother of the overflow item also moves one step up,
544 * but this does not affect bl_count[max_length]
547 } while (overflow
> 0);
549 /* Now recompute all bit lengths, scanning in increasing frequency.
550 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
551 * lengths instead of fixing only the wrong ones. This idea is taken
552 * from 'ar' written by Haruhiko Okumura.)
554 for (bits
= max_length
; bits
!= 0; bits
--) {
558 if (m
> max_code
) continue;
559 if (tree
[m
].Len
!= (unsigned) bits
) {
560 Trace((stderr
,"code %d bits %d->%d\n", m
, tree
[m
].Len
, bits
));
561 opt_len
+= ((long)bits
-(long)tree
[m
].Len
)*(long)tree
[m
].Freq
;
562 tree
[m
].Len
= (ush
)bits
;
569 /* ===========================================================================
570 * Generate the codes for a given tree and bit counts (which need not be
572 * IN assertion: the array bl_count contains the bit length statistics for
573 * the given tree and the field len is set for all tree elements.
574 * OUT assertion: the field code is set for all tree elements of non
577 local
void gen_codes (tree
, max_code
)
578 ct_data near
*tree
; /* the tree to decorate */
579 int max_code
; /* largest code with non zero frequency */
581 ush next_code
[MAX_BITS
+1]; /* next code value for each bit length */
582 ush code
= 0; /* running code value */
583 int bits
; /* bit index */
584 int n
; /* code index */
586 /* The distribution counts are first used to generate the code values
587 * without bit reversal.
589 for (bits
= 1; bits
<= MAX_BITS
; bits
++) {
590 next_code
[bits
] = code
= (code
+ bl_count
[bits
-1]) << 1;
592 /* Check that the bit counts in bl_count are consistent. The last code
595 Assert (code
+ bl_count
[MAX_BITS
]-1 == (1<<MAX_BITS
)-1,
596 "inconsistent bit counts");
597 Tracev((stderr
,"\ngen_codes: max_code %d ", max_code
));
599 for (n
= 0; n
<= max_code
; n
++) {
600 int len
= tree
[n
].Len
;
601 if (len
== 0) continue;
602 /* Now reverse the bits */
603 tree
[n
].Code
= bi_reverse(next_code
[len
]++, len
);
605 Tracec(tree
!= static_ltree
, (stderr
,"\nn %3d %c l %2d c %4x (%x) ",
606 n
, (isgraph(n
) ? n
: ' '), len
, tree
[n
].Code
, next_code
[len
]-1));
610 /* ===========================================================================
611 * Construct one Huffman tree and assigns the code bit strings and lengths.
612 * Update the total bit length for the current block.
613 * IN assertion: the field freq is set for all tree elements.
614 * OUT assertions: the fields len and code are set to the optimal bit length
615 * and corresponding code. The length opt_len is updated; static_len is
616 * also updated if stree is not null. The field max_code is set.
618 local
void build_tree(desc
)
619 tree_desc near
*desc
; /* the tree descriptor */
621 ct_data near
*tree
= desc
->dyn_tree
;
622 ct_data near
*stree
= desc
->static_tree
;
623 int elems
= desc
->elems
;
624 int n
, m
; /* iterate over heap elements */
625 int max_code
= -1; /* largest code with non zero frequency */
626 int node
= elems
; /* next internal node of the tree */
628 /* Construct the initial heap, with least frequent element in
629 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
630 * heap[0] is not used.
632 heap_len
= 0, heap_max
= HEAP_SIZE
;
634 for (n
= 0; n
< elems
; n
++) {
635 if (tree
[n
].Freq
!= 0) {
636 heap
[++heap_len
] = max_code
= n
;
643 /* The pkzip format requires that at least one distance code exists,
644 * and that at least one bit should be sent even if there is only one
645 * possible code. So to avoid special checks later on we force at least
646 * two codes of non zero frequency.
648 while (heap_len
< 2) {
649 int new = heap
[++heap_len
] = (max_code
< 2 ? ++max_code
: 0);
652 opt_len
--; if (stree
) static_len
-= stree
[new].Len
;
653 /* new is 0 or 1 so it does not have extra bits */
655 desc
->max_code
= max_code
;
657 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
658 * establish sub-heaps of increasing lengths:
660 for (n
= heap_len
/2; n
>= 1; n
--) pqdownheap(tree
, n
);
662 /* Construct the Huffman tree by repeatedly combining the least two
666 pqremove(tree
, n
); /* n = node of least frequency */
667 m
= heap
[SMALLEST
]; /* m = node of next least frequency */
669 heap
[--heap_max
] = n
; /* keep the nodes sorted by frequency */
670 heap
[--heap_max
] = m
;
672 /* Create a new node father of n and m */
673 tree
[node
].Freq
= tree
[n
].Freq
+ tree
[m
].Freq
;
674 depth
[node
] = (uch
) (MAX(depth
[n
], depth
[m
]) + 1);
675 tree
[n
].Dad
= tree
[m
].Dad
= (ush
)node
;
677 if (tree
== bl_tree
) {
678 fprintf(stderr
,"\nnode %d(%d), sons %d(%d) %d(%d)",
679 node
, tree
[node
].Freq
, n
, tree
[n
].Freq
, m
, tree
[m
].Freq
);
682 /* and insert the new node in the heap */
683 heap
[SMALLEST
] = node
++;
684 pqdownheap(tree
, SMALLEST
);
686 } while (heap_len
>= 2);
688 heap
[--heap_max
] = heap
[SMALLEST
];
690 /* At this point, the fields freq and dad are set. We can now
691 * generate the bit lengths.
693 gen_bitlen((tree_desc near
*)desc
);
695 /* The field len is now set, we can generate the bit codes */
696 gen_codes ((ct_data near
*)tree
, max_code
);
699 /* ===========================================================================
700 * Scan a literal or distance tree to determine the frequencies of the codes
701 * in the bit length tree. Updates opt_len to take into account the repeat
702 * counts. (The contribution of the bit length codes will be added later
703 * during the construction of bl_tree.)
705 local
void scan_tree (tree
, max_code
)
706 ct_data near
*tree
; /* the tree to be scanned */
707 int max_code
; /* and its largest code of non zero frequency */
709 int n
; /* iterates over all tree elements */
710 int prevlen
= -1; /* last emitted length */
711 int curlen
; /* length of current code */
712 int nextlen
= tree
[0].Len
; /* length of next code */
713 int count
= 0; /* repeat count of the current code */
714 int max_count
= 7; /* max repeat count */
715 int min_count
= 4; /* min repeat count */
717 if (nextlen
== 0) max_count
= 138, min_count
= 3;
718 tree
[max_code
+1].Len
= (ush
)0xffff; /* guard */
720 for (n
= 0; n
<= max_code
; n
++) {
721 curlen
= nextlen
; nextlen
= tree
[n
+1].Len
;
722 if (++count
< max_count
&& curlen
== nextlen
) {
724 } else if (count
< min_count
) {
725 bl_tree
[curlen
].Freq
+= count
;
726 } else if (curlen
!= 0) {
727 if (curlen
!= prevlen
) bl_tree
[curlen
].Freq
++;
728 bl_tree
[REP_3_6
].Freq
++;
729 } else if (count
<= 10) {
730 bl_tree
[REPZ_3_10
].Freq
++;
732 bl_tree
[REPZ_11_138
].Freq
++;
734 count
= 0; prevlen
= curlen
;
736 max_count
= 138, min_count
= 3;
737 } else if (curlen
== nextlen
) {
738 max_count
= 6, min_count
= 3;
740 max_count
= 7, min_count
= 4;
745 /* ===========================================================================
746 * Send a literal or distance tree in compressed form, using the codes in
749 local
void send_tree (tree
, max_code
)
750 ct_data near
*tree
; /* the tree to be scanned */
751 int max_code
; /* and its largest code of non zero frequency */
753 int n
; /* iterates over all tree elements */
754 int prevlen
= -1; /* last emitted length */
755 int curlen
; /* length of current code */
756 int nextlen
= tree
[0].Len
; /* length of next code */
757 int count
= 0; /* repeat count of the current code */
758 int max_count
= 7; /* max repeat count */
759 int min_count
= 4; /* min repeat count */
761 /* tree[max_code+1].Len = -1; */ /* guard already set */
762 if (nextlen
== 0) max_count
= 138, min_count
= 3;
764 for (n
= 0; n
<= max_code
; n
++) {
765 curlen
= nextlen
; nextlen
= tree
[n
+1].Len
;
766 if (++count
< max_count
&& curlen
== nextlen
) {
768 } else if (count
< min_count
) {
769 do { send_code(curlen
, bl_tree
); } while (--count
!= 0);
771 } else if (curlen
!= 0) {
772 if (curlen
!= prevlen
) {
773 send_code(curlen
, bl_tree
); count
--;
775 Assert(count
>= 3 && count
<= 6, " 3_6?");
776 send_code(REP_3_6
, bl_tree
); send_bits(count
-3, 2);
778 } else if (count
<= 10) {
779 send_code(REPZ_3_10
, bl_tree
); send_bits(count
-3, 3);
782 send_code(REPZ_11_138
, bl_tree
); send_bits(count
-11, 7);
784 count
= 0; prevlen
= curlen
;
786 max_count
= 138, min_count
= 3;
787 } else if (curlen
== nextlen
) {
788 max_count
= 6, min_count
= 3;
790 max_count
= 7, min_count
= 4;
795 /* ===========================================================================
796 * Construct the Huffman tree for the bit lengths and return the index in
797 * bl_order of the last bit length code to send.
799 local
int build_bl_tree()
801 int max_blindex
; /* index of last bit length code of non zero freq */
803 /* Determine the bit length frequencies for literal and distance trees */
804 scan_tree((ct_data near
*)dyn_ltree
, l_desc
.max_code
);
805 scan_tree((ct_data near
*)dyn_dtree
, d_desc
.max_code
);
807 /* Build the bit length tree: */
808 build_tree((tree_desc near
*)(&bl_desc
));
809 /* opt_len now includes the length of the tree representations, except
810 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
813 /* Determine the number of bit length codes to send. The pkzip format
814 * requires that at least 4 bit length codes be sent. (appnote.txt says
815 * 3 but the actual value used is 4.)
817 for (max_blindex
= BL_CODES
-1; max_blindex
>= 3; max_blindex
--) {
818 if (bl_tree
[bl_order
[max_blindex
]].Len
!= 0) break;
820 /* Update opt_len to include the bit length tree and counts */
821 opt_len
+= 3*(max_blindex
+1) + 5+5+4;
822 Tracev((stderr
, "\ndyn trees: dyn %lu, stat %lu", opt_len
, static_len
));
827 /* ===========================================================================
828 * Send the header for a block using dynamic Huffman trees: the counts, the
829 * lengths of the bit length codes, the literal tree and the distance tree.
830 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
832 local
void send_all_trees(lcodes
, dcodes
, blcodes
)
833 int lcodes
, dcodes
, blcodes
; /* number of codes for each tree */
835 int rank
; /* index in bl_order */
837 Assert (lcodes
>= 257 && dcodes
>= 1 && blcodes
>= 4, "not enough codes");
838 Assert (lcodes
<= L_CODES
&& dcodes
<= D_CODES
&& blcodes
<= BL_CODES
,
840 Tracev((stderr
, "\nbl counts: "));
841 send_bits(lcodes
-257, 5); /* not +255 as stated in appnote.txt */
842 send_bits(dcodes
-1, 5);
843 send_bits(blcodes
-4, 4); /* not -3 as stated in appnote.txt */
844 for (rank
= 0; rank
< blcodes
; rank
++) {
845 Tracev((stderr
, "\nbl code %2d ", bl_order
[rank
]));
846 send_bits(bl_tree
[bl_order
[rank
]].Len
, 3);
849 send_tree((ct_data near
*)dyn_ltree
, lcodes
-1); /* send the literal tree */
851 send_tree((ct_data near
*)dyn_dtree
, dcodes
-1); /* send the distance tree */
854 /* ===========================================================================
855 * Determine the best encoding for the current block: dynamic trees, static
856 * trees or store, and output the encoded block to the zip file. This function
857 * returns the total compressed length for the file so far.
859 off_t
flush_block(buf
, stored_len
, eof
)
860 char *buf
; /* input block, or NULL if too old */
861 ulg stored_len
; /* length of input block */
862 int eof
; /* true if this is the last block for a file */
864 ulg opt_lenb
, static_lenb
; /* opt_len and static_len in bytes */
865 int max_blindex
; /* index of last bit length code of non zero freq */
867 flag_buf
[last_flags
] = flags
; /* Save the flags for the last 8 items */
869 /* Check if the file is ascii or binary */
870 if (*file_type
== (ush
)UNKNOWN
) set_file_type();
872 /* Construct the literal and distance trees */
873 build_tree((tree_desc near
*)(&l_desc
));
874 Tracev((stderr
, "\nlit data: dyn %lu, stat %lu", opt_len
, static_len
));
876 build_tree((tree_desc near
*)(&d_desc
));
877 Tracev((stderr
, "\ndist data: dyn %lu, stat %lu", opt_len
, static_len
));
878 /* At this point, opt_len and static_len are the total bit lengths of
879 * the compressed block data, excluding the tree representations.
882 /* Build the bit length tree for the above two trees, and get the index
883 * in bl_order of the last bit length code to send.
885 max_blindex
= build_bl_tree();
887 /* Determine the best encoding. Compute first the block length in bytes */
888 opt_lenb
= (opt_len
+3+7)>>3;
889 static_lenb
= (static_len
+3+7)>>3;
890 input_len
+= stored_len
; /* for debugging only */
892 Trace((stderr
, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ",
893 opt_lenb
, opt_len
, static_lenb
, static_len
, stored_len
,
894 last_lit
, last_dist
));
896 if (static_lenb
<= opt_lenb
) opt_lenb
= static_lenb
;
898 /* If compression failed and this is the first and last block,
899 * and if the zip file can be seeked (to rewrite the local header),
900 * the whole file is transformed into a stored file:
903 if (level
== 1 && eof
&& compressed_len
== 0L) { /* force stored file */
905 if (stored_len
<= opt_lenb
&& eof
&& compressed_len
== 0L && seekable()) {
907 /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */
909 gzip_error ("block vanished");
911 copy_block(buf
, (unsigned)stored_len
, 0); /* without header */
912 compressed_len
= stored_len
<< 3;
913 *file_method
= STORED
;
916 } else if (level
== 2 && buf
!= (char*)0) { /* force stored block */
918 } else if (stored_len
+4 <= opt_lenb
&& buf
!= (char*)0) {
919 /* 4: two words for the lengths */
921 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
922 * Otherwise we can't have processed more than WSIZE input bytes since
923 * the last block flush, because compression would have been
924 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
925 * transform a block into a stored block.
927 send_bits((STORED_BLOCK
<<1)+eof
, 3); /* send block type */
928 compressed_len
= (compressed_len
+ 3 + 7) & ~7L;
929 compressed_len
+= (stored_len
+ 4) << 3;
931 copy_block(buf
, (unsigned)stored_len
, 1); /* with header */
934 } else if (level
== 3) { /* force static trees */
936 } else if (static_lenb
== opt_lenb
) {
938 send_bits((STATIC_TREES
<<1)+eof
, 3);
939 compress_block((ct_data near
*)static_ltree
, (ct_data near
*)static_dtree
);
940 compressed_len
+= 3 + static_len
;
942 send_bits((DYN_TREES
<<1)+eof
, 3);
943 send_all_trees(l_desc
.max_code
+1, d_desc
.max_code
+1, max_blindex
+1);
944 compress_block((ct_data near
*)dyn_ltree
, (ct_data near
*)dyn_dtree
);
945 compressed_len
+= 3 + opt_len
;
947 Assert (compressed_len
== bits_sent
, "bad compressed size");
951 Assert (input_len
== bytes_in
, "bad input size");
953 compressed_len
+= 7; /* align on byte boundary */
956 return compressed_len
>> 3;
959 /* ===========================================================================
960 * Save the match info and tally the frequency counts. Return true if
961 * the current block must be flushed.
963 int ct_tally (dist
, lc
)
964 int dist
; /* distance of matched string */
965 int lc
; /* match length-MIN_MATCH or unmatched char (if dist==0) */
967 l_buf
[last_lit
++] = (uch
)lc
;
969 /* lc is the unmatched char */
970 dyn_ltree
[lc
].Freq
++;
972 /* Here, lc is the match length - MIN_MATCH */
973 dist
--; /* dist = match distance - 1 */
974 Assert((ush
)dist
< (ush
)MAX_DIST
&&
975 (ush
)lc
<= (ush
)(MAX_MATCH
-MIN_MATCH
) &&
976 (ush
)d_code(dist
) < (ush
)D_CODES
, "ct_tally: bad match");
978 dyn_ltree
[length_code
[lc
]+LITERALS
+1].Freq
++;
979 dyn_dtree
[d_code(dist
)].Freq
++;
981 d_buf
[last_dist
++] = (ush
)dist
;
986 /* Output the flags if they fill a byte: */
987 if ((last_lit
& 7) == 0) {
988 flag_buf
[last_flags
++] = flags
;
989 flags
= 0, flag_bit
= 1;
991 /* Try to guess if it is profitable to stop the current block here */
992 if (level
> 2 && (last_lit
& 0xfff) == 0) {
993 /* Compute an upper bound for the compressed length */
994 ulg out_length
= (ulg
)last_lit
*8L;
995 ulg in_length
= (ulg
)strstart
-block_start
;
997 for (dcode
= 0; dcode
< D_CODES
; dcode
++) {
998 out_length
+= (ulg
)dyn_dtree
[dcode
].Freq
*(5L+extra_dbits
[dcode
]);
1001 Trace((stderr
,"\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ",
1002 last_lit
, last_dist
, in_length
, out_length
,
1003 100L - out_length
*100L/in_length
));
1004 if (last_dist
< last_lit
/2 && out_length
< in_length
/2) return 1;
1006 return (last_lit
== LIT_BUFSIZE
-1 || last_dist
== DIST_BUFSIZE
);
1007 /* We avoid equality with LIT_BUFSIZE because of wraparound at 64K
1008 * on 16 bit machines and because stored blocks are restricted to
1013 /* ===========================================================================
1014 * Send the block data compressed using the given Huffman trees
1016 local
void compress_block(ltree
, dtree
)
1017 ct_data near
*ltree
; /* literal tree */
1018 ct_data near
*dtree
; /* distance tree */
1020 unsigned dist
; /* distance of matched string */
1021 int lc
; /* match length or unmatched char (if dist == 0) */
1022 unsigned lx
= 0; /* running index in l_buf */
1023 unsigned dx
= 0; /* running index in d_buf */
1024 unsigned fx
= 0; /* running index in flag_buf */
1025 uch flag
= 0; /* current flags */
1026 unsigned code
; /* the code to send */
1027 int extra
; /* number of extra bits to send */
1029 if (last_lit
!= 0) do {
1030 if ((lx
& 7) == 0) flag
= flag_buf
[fx
++];
1032 if ((flag
& 1) == 0) {
1033 send_code(lc
, ltree
); /* send a literal byte */
1034 Tracecv(isgraph(lc
), (stderr
," '%c' ", lc
));
1036 /* Here, lc is the match length - MIN_MATCH */
1037 code
= length_code
[lc
];
1038 send_code(code
+LITERALS
+1, ltree
); /* send the length code */
1039 extra
= extra_lbits
[code
];
1041 lc
-= base_length
[code
];
1042 send_bits(lc
, extra
); /* send the extra length bits */
1045 /* Here, dist is the match distance - 1 */
1046 code
= d_code(dist
);
1047 Assert (code
< D_CODES
, "bad d_code");
1049 send_code(code
, dtree
); /* send the distance code */
1050 extra
= extra_dbits
[code
];
1052 dist
-= base_dist
[code
];
1053 send_bits(dist
, extra
); /* send the extra distance bits */
1055 } /* literal or match pair ? */
1057 } while (lx
< last_lit
);
1059 send_code(END_BLOCK
, ltree
);
1062 /* ===========================================================================
1063 * Set the file type to ASCII or BINARY, using a crude approximation:
1064 * binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise.
1065 * IN assertion: the fields freq of dyn_ltree are set and the total of all
1066 * frequencies does not exceed 64K (to fit in an int on 16 bit machines).
1068 local
void set_file_type()
1071 unsigned ascii_freq
= 0;
1072 unsigned bin_freq
= 0;
1073 while (n
< 7) bin_freq
+= dyn_ltree
[n
++].Freq
;
1074 while (n
< 128) ascii_freq
+= dyn_ltree
[n
++].Freq
;
1075 while (n
< LITERALS
) bin_freq
+= dyn_ltree
[n
++].Freq
;
1076 *file_type
= bin_freq
> (ascii_freq
>> 2) ? BINARY
: ASCII
;
1077 if (*file_type
== BINARY
&& translate_eol
) {
1078 warning ("-l used on binary file");