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1060 lines
38 KiB
1060 lines
38 KiB
/* trees.c -- output deflated data using Huffman coding |
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* Copyright (C) 1995 Jean-loup Gailly |
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* For conditions of distribution and use, see copyright notice in zlib.h |
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*/ |
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|
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/* |
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* ALGORITHM |
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* |
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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. |
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* |
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* 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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* |
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* REFERENCES |
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* |
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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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* |
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* Storer, James A. |
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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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* |
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* Sedgewick, R. |
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* Algorithms, p290. |
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* Addison-Wesley, 1983. ISBN 0-201-06672-6. |
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*/ |
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/* $Id: trees.c,v 1.4 1995/05/01 16:53:44 jloup Exp $ */ |
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#include "deflate.h" |
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#ifdef DEBUG |
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# include <ctype.h> |
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#endif |
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/* =========================================================================== |
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* Constants |
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*/ |
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#define MAX_BL_BITS 7 |
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/* Bit length codes must not exceed MAX_BL_BITS bits */ |
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#define END_BLOCK 256 |
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/* end of block literal code */ |
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#define REP_3_6 16 |
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/* repeat previous bit length 3-6 times (2 bits of repeat count) */ |
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#define REPZ_3_10 17 |
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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 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 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 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 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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*/ |
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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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*/ |
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/* =========================================================================== |
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* Local data. These are initialized only once. |
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* To do: initialize at compile time to be completely reentrant. ??? |
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*/ |
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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 ct_init |
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* below). |
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*/ |
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local ct_data static_dtree[D_CODES]; |
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/* The static distance tree. (Actually a trivial tree since all codes use |
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* 5 bits.) |
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*/ |
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local uch dist_code[512]; |
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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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*/ |
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local 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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struct static_tree_desc_s { |
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ct_data *static_tree; /* static tree or NULL */ |
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int *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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}; |
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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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{(ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS}; |
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/* =========================================================================== |
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* Local (static) routines in this file. |
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*/ |
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local void ct_static_init __P((void)); |
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local void init_block __P((deflate_state *s)); |
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local void pqdownheap __P((deflate_state *s, ct_data *tree, int k)); |
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local void gen_bitlen __P((deflate_state *s, tree_desc *desc)); |
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local void gen_codes __P((ct_data *tree, int max_code, ush bl_count[])); |
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local void build_tree __P((deflate_state *s, tree_desc *desc)); |
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local void scan_tree __P((deflate_state *s, ct_data *tree, int max_code)); |
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local void send_tree __P((deflate_state *s, ct_data *tree, int max_code)); |
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local int build_bl_tree __P((deflate_state *s)); |
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local void send_all_trees __P((deflate_state *s, int lcodes, int dcodes, |
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int blcodes)); |
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local void compress_block __P((deflate_state *s, ct_data *ltree, |
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ct_data *dtree)); |
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local void set_data_type __P((deflate_state *s)); |
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local void send_bits __P((deflate_state *s, int value, int length)); |
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local unsigned bi_reverse __P((unsigned value, int length)); |
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local void bi_windup __P((deflate_state *s)); |
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local void copy_block __P((deflate_state *s, char *buf, unsigned len, |
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int header)); |
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#ifndef DEBUG |
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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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#else /* DEBUG */ |
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# define send_code(s, c, tree) \ |
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{ if (verbose>1) fprintf(stderr,"\ncd %3d ",(c)); \ |
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send_bits(s, tree[c].Code, tree[c].Len); } |
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#endif |
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#define d_code(dist) \ |
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((dist) < 256 ? dist_code[dist] : dist_code[256+((dist)>>7)]) |
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/* Mapping from a distance to a distance code. dist is the distance - 1 and |
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* must not have side effects. dist_code[256] and dist_code[257] are never |
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* used. |
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*/ |
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#define MAX(a,b) (a >= b ? a : b) |
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/* the arguments must not have side effects */ |
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/* =========================================================================== |
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* Initialize the various 'constant' tables. |
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* To do: do this at compile time. |
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*/ |
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local void ct_static_init() |
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{ |
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int n; /* iterates over tree elements */ |
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int bits; /* bit counter */ |
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int length; /* length value */ |
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int code; /* code value */ |
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int dist; /* distance index */ |
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ush bl_count[MAX_BITS+1]; |
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/* number of codes at each bit length for an optimal tree */ |
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/* Initialize the mapping length (0..255) -> length code (0..28) */ |
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length = 0; |
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for (code = 0; code < LENGTH_CODES-1; code++) { |
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base_length[code] = length; |
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for (n = 0; n < (1<<extra_lbits[code]); n++) { |
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length_code[length++] = (uch)code; |
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} |
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} |
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Assert (length == 256, "ct_static_init: length != 256"); |
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/* Note that the length 255 (match length 258) can be represented |
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* in two different ways: code 284 + 5 bits or code 285, so we |
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* overwrite length_code[255] to use the best encoding: |
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*/ |
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length_code[length-1] = (uch)code; |
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/* Initialize the mapping dist (0..32K) -> dist code (0..29) */ |
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dist = 0; |
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for (code = 0 ; code < 16; code++) { |
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base_dist[code] = dist; |
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for (n = 0; n < (1<<extra_dbits[code]); n++) { |
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dist_code[dist++] = (uch)code; |
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} |
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} |
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Assert (dist == 256, "ct_static_init: dist != 256"); |
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dist >>= 7; /* from now on, all distances are divided by 128 */ |
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for ( ; code < D_CODES; code++) { |
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base_dist[code] = dist << 7; |
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for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) { |
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dist_code[256 + dist++] = (uch)code; |
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} |
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} |
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Assert (dist == 256, "ct_static_init: 256+dist != 512"); |
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/* Construct the codes of the static literal tree */ |
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for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0; |
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n = 0; |
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while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++; |
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while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++; |
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while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++; |
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while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++; |
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/* Codes 286 and 287 do not exist, but we must include them in the |
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* tree construction to get a canonical Huffman tree (longest code |
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* all ones) |
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*/ |
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gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count); |
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/* The static distance tree is trivial: */ |
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for (n = 0; n < D_CODES; n++) { |
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static_dtree[n].Len = 5; |
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static_dtree[n].Code = bi_reverse(n, 5); |
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} |
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} |
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/* =========================================================================== |
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* Initialize the tree data structures for a new zlib stream. |
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*/ |
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void ct_init(s) |
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deflate_state *s; |
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{ |
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if (static_dtree[0].Len == 0) { |
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ct_static_init(); /* To do: at compile time */ |
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} |
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s->compressed_len = 0L; |
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s->l_desc.dyn_tree = s->dyn_ltree; |
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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; |
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s->bl_desc.stat_desc = &static_bl_desc; |
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s->bi_buf = 0; |
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s->bi_valid = 0; |
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#ifdef DEBUG |
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s->bits_sent = 0L; |
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#endif |
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/* Initialize the first block of the first file: */ |
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init_block(s); |
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} |
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/* =========================================================================== |
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* Initialize a new block. |
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*/ |
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local void init_block(s) |
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deflate_state *s; |
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{ |
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int n; /* iterates over tree elements */ |
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/* Initialize the trees. */ |
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for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0; |
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for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0; |
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for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0; |
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s->dyn_ltree[END_BLOCK].Freq = 1; |
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s->opt_len = s->static_len = 0L; |
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s->last_lit = s->matches = 0; |
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} |
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#define SMALLEST 1 |
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/* Index within the heap array of least frequent node in the Huffman tree */ |
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/* =========================================================================== |
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* Remove the smallest element from the heap and recreate the heap with |
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* one less element. Updates heap and heap_len. |
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*/ |
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#define pqremove(s, tree, top) \ |
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{\ |
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top = s->heap[SMALLEST]; \ |
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s->heap[SMALLEST] = s->heap[s->heap_len--]; \ |
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pqdownheap(s, tree, SMALLEST); \ |
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} |
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/* =========================================================================== |
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* Compares to subtrees, using the tree depth as tie breaker when |
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* the subtrees have equal frequency. This minimizes the worst case length. |
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*/ |
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#define smaller(tree, n, m, depth) \ |
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(tree[n].Freq < tree[m].Freq || \ |
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(tree[n].Freq == tree[m].Freq && depth[n] <= depth[m])) |
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|
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/* =========================================================================== |
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* Restore the heap property by moving down the tree starting at node k, |
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* exchanging a node with the smallest of its two sons if necessary, stopping |
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* when the heap property is re-established (each father smaller than its |
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* two sons). |
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*/ |
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local void pqdownheap(s, tree, k) |
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deflate_state *s; |
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ct_data *tree; /* the tree to restore */ |
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int k; /* node to move down */ |
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{ |
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int v = s->heap[k]; |
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int j = k << 1; /* left son of k */ |
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while (j <= s->heap_len) { |
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/* Set j to the smallest of the two sons: */ |
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if (j < s->heap_len && |
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smaller(tree, s->heap[j+1], s->heap[j], s->depth)) { |
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j++; |
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} |
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/* Exit if v is smaller than both sons */ |
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if (smaller(tree, v, s->heap[j], s->depth)) break; |
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/* Exchange v with the smallest son */ |
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s->heap[k] = s->heap[j]; k = j; |
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/* And continue down the tree, setting j to the left son of k */ |
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j <<= 1; |
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} |
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s->heap[k] = v; |
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} |
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/* =========================================================================== |
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* Compute the optimal bit lengths for a tree and update the total bit length |
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* for the current block. |
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* IN assertion: the fields freq and dad are set, heap[heap_max] and |
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* above are the tree nodes sorted by increasing frequency. |
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* OUT assertions: the field len is set to the optimal bit length, the |
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* array bl_count contains the frequencies for each bit length. |
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* The length opt_len is updated; static_len is also updated if stree is |
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* not null. |
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*/ |
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local void gen_bitlen(s, desc) |
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deflate_state *s; |
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tree_desc *desc; /* the tree descriptor */ |
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{ |
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ct_data *tree = desc->dyn_tree; |
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int max_code = desc->max_code; |
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ct_data *stree = desc->stat_desc->static_tree; |
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int *extra = desc->stat_desc->extra_bits; |
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int base = desc->stat_desc->extra_base; |
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int max_length = desc->stat_desc->max_length; |
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int h; /* heap index */ |
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int n, m; /* iterate over the tree elements */ |
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int bits; /* bit length */ |
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int xbits; /* extra bits */ |
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ush f; /* frequency */ |
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int overflow = 0; /* number of elements with bit length too large */ |
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for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0; |
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|
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/* In a first pass, compute the optimal bit lengths (which may |
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* overflow in the case of the bit length tree). |
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*/ |
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tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */ |
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for (h = s->heap_max+1; h < HEAP_SIZE; h++) { |
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n = s->heap[h]; |
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bits = tree[tree[n].Dad].Len + 1; |
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if (bits > max_length) bits = max_length, overflow++; |
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tree[n].Len = (ush)bits; |
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/* We overwrite tree[n].Dad which is no longer needed */ |
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if (n > max_code) continue; /* not a leaf node */ |
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s->bl_count[bits]++; |
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xbits = 0; |
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if (n >= base) xbits = extra[n-base]; |
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f = tree[n].Freq; |
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s->opt_len += (ulg)f * (bits + xbits); |
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if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits); |
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} |
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if (overflow == 0) return; |
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Trace((stderr,"\nbit length overflow\n")); |
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/* This happens for example on obj2 and pic of the Calgary corpus */ |
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/* Find the first bit length which could increase: */ |
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do { |
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bits = max_length-1; |
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while (s->bl_count[bits] == 0) bits--; |
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s->bl_count[bits]--; /* move one leaf down the tree */ |
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s->bl_count[bits+1] += 2; /* move one overflow item as its brother */ |
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s->bl_count[max_length]--; |
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/* The brother of the overflow item also moves one step up, |
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* but this does not affect bl_count[max_length] |
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*/ |
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overflow -= 2; |
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} while (overflow > 0); |
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|
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/* Now recompute all bit lengths, scanning in increasing frequency. |
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* h is still equal to HEAP_SIZE. (It is simpler to reconstruct all |
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* lengths instead of fixing only the wrong ones. This idea is taken |
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* from 'ar' written by Haruhiko Okumura.) |
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*/ |
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for (bits = max_length; bits != 0; bits--) { |
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n = s->bl_count[bits]; |
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while (n != 0) { |
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m = s->heap[--h]; |
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if (m > max_code) continue; |
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if (tree[m].Len != (unsigned) bits) { |
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Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits)); |
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s->opt_len += ((long)bits - (long)tree[m].Len) |
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*(long)tree[m].Freq; |
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tree[m].Len = (ush)bits; |
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} |
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n--; |
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} |
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} |
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} |
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|
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/* =========================================================================== |
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* Generate the codes for a given tree and bit counts (which need not be |
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* optimal). |
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* IN assertion: the array bl_count contains the bit length statistics for |
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* the given tree and the field len is set for all tree elements. |
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* OUT assertion: the field code is set for all tree elements of non |
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* zero code length. |
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*/ |
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local void gen_codes (tree, max_code, bl_count) |
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ct_data *tree; /* the tree to decorate */ |
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int max_code; /* largest code with non zero frequency */ |
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ush bl_count[]; /* number of codes at each bit length */ |
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{ |
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ush next_code[MAX_BITS+1]; /* next code value for each bit length */ |
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ush code = 0; /* running code value */ |
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int bits; /* bit index */ |
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int n; /* code index */ |
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|
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/* The distribution counts are first used to generate the code values |
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* without bit reversal. |
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*/ |
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for (bits = 1; bits <= MAX_BITS; bits++) { |
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next_code[bits] = code = (code + bl_count[bits-1]) << 1; |
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} |
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/* Check that the bit counts in bl_count are consistent. The last code |
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* must be all ones. |
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*/ |
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Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1, |
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"inconsistent bit counts"); |
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Tracev((stderr,"\ngen_codes: max_code %d ", max_code)); |
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|
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for (n = 0; n <= max_code; n++) { |
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int len = tree[n].Len; |
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if (len == 0) continue; |
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/* Now reverse the bits */ |
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tree[n].Code = bi_reverse(next_code[len]++, len); |
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|
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Tracec(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ", |
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n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1)); |
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} |
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} |
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|
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/* =========================================================================== |
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* Construct one Huffman tree and assigns the code bit strings and lengths. |
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* Update the total bit length for the current block. |
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* IN assertion: the field freq is set for all tree elements. |
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* OUT assertions: the fields len and code are set to the optimal bit length |
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* and corresponding code. The length opt_len is updated; static_len is |
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* also updated if stree is not null. The field max_code is set. |
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*/ |
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local void build_tree(s, desc) |
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deflate_state *s; |
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tree_desc *desc; /* the tree descriptor */ |
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{ |
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ct_data *tree = desc->dyn_tree; |
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ct_data *stree = desc->stat_desc->static_tree; |
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int elems = desc->stat_desc->elems; |
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int n, m; /* iterate over heap elements */ |
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int max_code = -1; /* largest code with non zero frequency */ |
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int node = elems; /* next internal node of the tree */ |
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int new; /* new node being created */ |
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|
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/* Construct the initial heap, with least frequent element in |
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* heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1]. |
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* heap[0] is not used. |
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*/ |
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s->heap_len = 0, s->heap_max = HEAP_SIZE; |
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|
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for (n = 0; n < elems; n++) { |
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if (tree[n].Freq != 0) { |
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s->heap[++(s->heap_len)] = max_code = n; |
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s->depth[n] = 0; |
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} 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) { |
|
new = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0); |
|
tree[new].Freq = 1; |
|
s->depth[new] = 0; |
|
s->opt_len--; if (stree) s->static_len -= stree[new].Len; |
|
/* new 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. |
|
*/ |
|
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) (MAX(s->depth[n], s->depth[m]) + 1); |
|
tree[n].Dad = tree[m].Dad = (ush)node; |
|
#ifdef DUMP_BL_TREE |
|
if (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 ct_stored_block(s, buf, stored_len, eof) |
|
deflate_state *s; |
|
char *buf; /* input block */ |
|
ulg stored_len; /* length of input block */ |
|
int eof; /* true if this is the last block for a file */ |
|
{ |
|
send_bits(s, (STORED_BLOCK<<1)+eof, 3); /* send block type */ |
|
s->compressed_len = (s->compressed_len + 3 + 7) & ~7L; |
|
s->compressed_len += (stored_len + 4) << 3; |
|
|
|
copy_block(s, buf, (unsigned)stored_len, 1); /* with header */ |
|
} |
|
|
|
/* =========================================================================== |
|
* Determine the best encoding for the current block: dynamic trees, static |
|
* trees or store, and output the encoded block to the zip file. This function |
|
* returns the total compressed length for the file so far. |
|
*/ |
|
ulg ct_flush_block(s, buf, stored_len, eof) |
|
deflate_state *s; |
|
char *buf; /* input block, or NULL if too old */ |
|
ulg stored_len; /* length of input block */ |
|
int eof; /* true if this is the last block for a file */ |
|
{ |
|
ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */ |
|
int max_blindex; /* index of last bit length code of non zero freq */ |
|
|
|
/* Check if the file is ascii or binary */ |
|
if (s->data_type == UNKNOWN) set_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 first the block length 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; |
|
|
|
/* If compression failed and this is the first and last block, |
|
* and if the .zip file can be seeked (to rewrite the local header), |
|
* the whole file is transformed into a stored file: |
|
*/ |
|
#ifdef STORED_FILE_OK |
|
# ifdef FORCE_STORED_FILE |
|
if (eof && compressed_len == 0L) { /* force stored file */ |
|
# else |
|
if (stored_len <= opt_lenb && eof && s->compressed_len==0L && seekable()) { |
|
# endif |
|
/* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */ |
|
if (buf == (char*)0) error ("block vanished"); |
|
|
|
copy_block(buf, (unsigned)stored_len, 0); /* without header */ |
|
s->compressed_len = stored_len << 3; |
|
s->method = STORED; |
|
} else |
|
#endif /* STORED_FILE_OK */ |
|
|
|
#ifdef FORCE_STORED |
|
if (buf != (char*)0) { /* force stored block */ |
|
#else |
|
if (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. |
|
*/ |
|
ct_stored_block(s, buf, stored_len, eof); |
|
|
|
#ifdef FORCE_STATIC |
|
} else if (static_lenb >= 0) { /* force static trees */ |
|
#else |
|
} else if (static_lenb == opt_lenb) { |
|
#endif |
|
send_bits(s, (STATIC_TREES<<1)+eof, 3); |
|
compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree); |
|
s->compressed_len += 3 + s->static_len; |
|
} else { |
|
send_bits(s, (DYN_TREES<<1)+eof, 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); |
|
s->compressed_len += 3 + s->opt_len; |
|
} |
|
Assert (s->compressed_len == s->bits_sent, "bad compressed size"); |
|
init_block(s); |
|
|
|
if (eof) { |
|
bi_windup(s); |
|
s->compressed_len += 7; /* align on byte boundary */ |
|
} |
|
Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3, |
|
s->compressed_len-7*eof)); |
|
|
|
return s->compressed_len >> 3; |
|
} |
|
|
|
/* =========================================================================== |
|
* Save the match info and tally the frequency counts. Return true if |
|
* the current block must be flushed. |
|
*/ |
|
int ct_tally (s, dist, lc) |
|
deflate_state *s; |
|
int dist; /* distance of matched string */ |
|
int 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, "ct_tally: bad match"); |
|
|
|
s->dyn_ltree[length_code[lc]+LITERALS+1].Freq++; |
|
s->dyn_dtree[d_code(dist)].Freq++; |
|
} |
|
|
|
/* Try to guess if it is profitable to stop the current block here */ |
|
if (s->level > 2 && (s->last_lit & 0xfff) == 0) { |
|
/* Compute an upper bound for the compressed length */ |
|
ulg out_length = (ulg)s->last_lit*8L; |
|
ulg in_length = (ulg)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; |
|
} |
|
return (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(s->pending < s->lit_bufsize + 2*lx, "pendingBuf overflow"); |
|
|
|
} while (lx < s->last_lit); |
|
|
|
send_code(s, END_BLOCK, ltree); |
|
} |
|
|
|
/* =========================================================================== |
|
* Set the data type to ASCII or BINARY, using a crude approximation: |
|
* binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise. |
|
* IN assertion: the fields freq of dyn_ltree are set and the total of all |
|
* frequencies does not exceed 64K (to fit in an int on 16 bit machines). |
|
*/ |
|
local void set_data_type(s) |
|
deflate_state *s; |
|
{ |
|
int n = 0; |
|
unsigned ascii_freq = 0; |
|
unsigned bin_freq = 0; |
|
while (n < 7) bin_freq += s->dyn_ltree[n++].Freq; |
|
while (n < 128) ascii_freq += s->dyn_ltree[n++].Freq; |
|
while (n < LITERALS) bin_freq += s->dyn_ltree[n++].Freq; |
|
s->data_type = (Byte)(bin_freq > (ascii_freq >> 2) ? BINARY : ASCII); |
|
} |
|
|
|
/* =========================================================================== |
|
* 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. |
|
*/ |
|
local void send_bits(s, value, length) |
|
deflate_state *s; |
|
int value; /* value to send */ |
|
int length; /* number of bits */ |
|
{ |
|
#ifdef DEBUG |
|
Tracev((stderr," l %2d v %4x ", length, value)); |
|
Assert(length > 0 && length <= 15, "invalid length"); |
|
s->bits_sent += (ulg)length; |
|
#endif |
|
/* 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 |= (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 |= value << s->bi_valid; |
|
s->bi_valid += length; |
|
} |
|
} |
|
|
|
/* =========================================================================== |
|
* 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; |
|
} |
|
|
|
/* =========================================================================== |
|
* Write out any remaining bits in an incomplete byte. |
|
*/ |
|
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 DEBUG |
|
s->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; |
|
char *buf; /* the input data */ |
|
unsigned len; /* its length */ |
|
int header; /* true if block header must be written */ |
|
{ |
|
bi_windup(s); /* align on byte boundary */ |
|
|
|
if (header) { |
|
put_short(s, (ush)len); |
|
put_short(s, (ush)~len); |
|
#ifdef DEBUG |
|
s->bits_sent += 2*16; |
|
#endif |
|
} |
|
#ifdef DEBUG |
|
s->bits_sent += (ulg)len<<3; |
|
#endif |
|
while (len--) { |
|
put_byte(s, *buf++); |
|
} |
|
}
|
|
|