1114 lines
40 KiB
C
1114 lines
40 KiB
C
/* +++ trees.c */
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/* trees.c -- output deflated data using Huffman coding
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* Copyright (C) 1995-1996 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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* 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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/* From: trees.c,v 1.11 1996/07/24 13:41:06 me Exp $ */
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/* #include "deflate.h" */
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#include <linux/zutil.h>
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#include "defutil.h"
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#ifdef DEBUG_ZLIB
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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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static const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
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= {0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0};
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static const int extra_dbits[D_CODES] /* extra bits for each distance code */
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= {0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13};
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static const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
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= {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
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static const uch bl_order[BL_CODES]
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= {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
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/* The lengths of the bit length codes are sent in order of decreasing
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* probability, to avoid transmitting the lengths for unused bit length codes.
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*/
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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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*/
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static 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 zlib_tr_init
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* below).
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*/
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static 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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static 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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static 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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static int base_length[LENGTH_CODES];
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/* First normalized length for each code (0 = MIN_MATCH) */
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static 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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const ct_data *static_tree; /* static tree or NULL */
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const 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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static static_tree_desc static_l_desc =
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{static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
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static static_tree_desc static_d_desc =
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{static_dtree, extra_dbits, 0, D_CODES, MAX_BITS};
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static static_tree_desc static_bl_desc =
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{(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS};
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/* ===========================================================================
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* Local (static) routines in this file.
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*/
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static void tr_static_init (void);
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static void init_block (deflate_state *s);
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static void pqdownheap (deflate_state *s, ct_data *tree, int k);
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static void gen_bitlen (deflate_state *s, tree_desc *desc);
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static void gen_codes (ct_data *tree, int max_code, ush *bl_count);
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static void build_tree (deflate_state *s, tree_desc *desc);
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static void scan_tree (deflate_state *s, ct_data *tree, int max_code);
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static void send_tree (deflate_state *s, ct_data *tree, int max_code);
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static int build_bl_tree (deflate_state *s);
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static void send_all_trees (deflate_state *s, int lcodes, int dcodes,
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int blcodes);
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static void compress_block (deflate_state *s, ct_data *ltree,
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ct_data *dtree);
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static void set_data_type (deflate_state *s);
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static unsigned bi_reverse (unsigned value, int length);
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static void bi_windup (deflate_state *s);
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static void bi_flush (deflate_state *s);
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static void copy_block (deflate_state *s, char *buf, unsigned len,
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int header);
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#ifndef DEBUG_ZLIB
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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_ZLIB */
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# define send_code(s, c, tree) \
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{ if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
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send_bits(s, tree[c].Code, tree[c].Len); }
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#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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/* ===========================================================================
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* Send a value on a given number of bits.
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* IN assertion: length <= 16 and value fits in length bits.
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*/
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#ifdef DEBUG_ZLIB
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static void send_bits (deflate_state *s, int value, int length);
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static void send_bits(
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deflate_state *s,
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int value, /* value to send */
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int length /* number of bits */
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)
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{
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Tracevv((stderr," l %2d v %4x ", length, value));
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Assert(length > 0 && length <= 15, "invalid length");
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s->bits_sent += (ulg)length;
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/* If not enough room in bi_buf, use (valid) bits from bi_buf and
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* (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
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* unused bits in value.
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*/
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if (s->bi_valid > (int)Buf_size - length) {
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s->bi_buf |= (value << s->bi_valid);
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put_short(s, s->bi_buf);
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s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
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s->bi_valid += length - Buf_size;
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} else {
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s->bi_buf |= value << s->bi_valid;
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s->bi_valid += length;
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}
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}
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#else /* !DEBUG_ZLIB */
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#define send_bits(s, value, length) \
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{ int len = length;\
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if (s->bi_valid > (int)Buf_size - len) {\
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int val = value;\
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s->bi_buf |= (val << s->bi_valid);\
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put_short(s, s->bi_buf);\
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s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
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s->bi_valid += len - Buf_size;\
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} else {\
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s->bi_buf |= (value) << s->bi_valid;\
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s->bi_valid += len;\
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}\
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}
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#endif /* DEBUG_ZLIB */
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/* ===========================================================================
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* Initialize the various 'constant' tables. In a multi-threaded environment,
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* this function may be called by two threads concurrently, but this is
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* harmless since both invocations do exactly the same thing.
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*/
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static void tr_static_init(void)
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{
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static int static_init_done;
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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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if (static_init_done) return;
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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, "tr_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, "tr_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, "tr_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((unsigned)n, 5);
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}
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static_init_done = 1;
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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 zlib_tr_init(
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deflate_state *s
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)
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{
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tr_static_init();
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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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s->last_eob_len = 8; /* enough lookahead for inflate */
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#ifdef DEBUG_ZLIB
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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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static void init_block(
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deflate_state *s
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)
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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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* 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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static void pqdownheap(
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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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{
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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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static void gen_bitlen(
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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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{
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ct_data *tree = desc->dyn_tree;
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int max_code = desc->max_code;
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const ct_data *stree = desc->stat_desc->static_tree;
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const 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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/* 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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/* Now recompute all bit lengths, scanning in increasing frequency.
|
|
* h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
|
|
* lengths instead of fixing only the wrong ones. This idea is taken
|
|
* from 'ar' written by Haruhiko Okumura.)
|
|
*/
|
|
for (bits = max_length; bits != 0; bits--) {
|
|
n = s->bl_count[bits];
|
|
while (n != 0) {
|
|
m = s->heap[--h];
|
|
if (m > max_code) continue;
|
|
if (tree[m].Len != (unsigned) bits) {
|
|
Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
|
|
s->opt_len += ((long)bits - (long)tree[m].Len)
|
|
*(long)tree[m].Freq;
|
|
tree[m].Len = (ush)bits;
|
|
}
|
|
n--;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* ===========================================================================
|
|
* Generate the codes for a given tree and bit counts (which need not be
|
|
* optimal).
|
|
* IN assertion: the array bl_count contains the bit length statistics for
|
|
* the given tree and the field len is set for all tree elements.
|
|
* OUT assertion: the field code is set for all tree elements of non
|
|
* zero code length.
|
|
*/
|
|
static void gen_codes(
|
|
ct_data *tree, /* the tree to decorate */
|
|
int max_code, /* largest code with non zero frequency */
|
|
ush *bl_count /* number of codes at each bit length */
|
|
)
|
|
{
|
|
ush next_code[MAX_BITS+1]; /* next code value for each bit length */
|
|
ush code = 0; /* running code value */
|
|
int bits; /* bit index */
|
|
int n; /* code index */
|
|
|
|
/* The distribution counts are first used to generate the code values
|
|
* without bit reversal.
|
|
*/
|
|
for (bits = 1; bits <= MAX_BITS; bits++) {
|
|
next_code[bits] = code = (code + bl_count[bits-1]) << 1;
|
|
}
|
|
/* Check that the bit counts in bl_count are consistent. The last code
|
|
* must be all ones.
|
|
*/
|
|
Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
|
|
"inconsistent bit counts");
|
|
Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
|
|
|
|
for (n = 0; n <= max_code; n++) {
|
|
int len = tree[n].Len;
|
|
if (len == 0) continue;
|
|
/* Now reverse the bits */
|
|
tree[n].Code = bi_reverse(next_code[len]++, len);
|
|
|
|
Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
|
|
n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
|
|
}
|
|
}
|
|
|
|
/* ===========================================================================
|
|
* Construct one Huffman tree and assigns the code bit strings and lengths.
|
|
* Update the total bit length for the current block.
|
|
* IN assertion: the field freq is set for all tree elements.
|
|
* OUT assertions: the fields len and code are set to the optimal bit length
|
|
* and corresponding code. The length opt_len is updated; static_len is
|
|
* also updated if stree is not null. The field max_code is set.
|
|
*/
|
|
static void build_tree(
|
|
deflate_state *s,
|
|
tree_desc *desc /* the tree descriptor */
|
|
)
|
|
{
|
|
ct_data *tree = desc->dyn_tree;
|
|
const ct_data *stree = desc->stat_desc->static_tree;
|
|
int elems = desc->stat_desc->elems;
|
|
int n, m; /* iterate over heap elements */
|
|
int max_code = -1; /* largest code with non zero frequency */
|
|
int node; /* new node being created */
|
|
|
|
/* Construct the initial heap, with least frequent element in
|
|
* heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
|
|
* heap[0] is not used.
|
|
*/
|
|
s->heap_len = 0, s->heap_max = HEAP_SIZE;
|
|
|
|
for (n = 0; n < elems; n++) {
|
|
if (tree[n].Freq != 0) {
|
|
s->heap[++(s->heap_len)] = max_code = n;
|
|
s->depth[n] = 0;
|
|
} else {
|
|
tree[n].Len = 0;
|
|
}
|
|
}
|
|
|
|
/* The pkzip format requires that at least one distance code exists,
|
|
* and that at least one bit should be sent even if there is only one
|
|
* possible code. So to avoid special checks later on we force at least
|
|
* two codes of non zero frequency.
|
|
*/
|
|
while (s->heap_len < 2) {
|
|
node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
|
|
tree[node].Freq = 1;
|
|
s->depth[node] = 0;
|
|
s->opt_len--; if (stree) s->static_len -= stree[node].Len;
|
|
/* node is 0 or 1 so it does not have extra bits */
|
|
}
|
|
desc->max_code = max_code;
|
|
|
|
/* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
|
|
* establish sub-heaps of increasing lengths:
|
|
*/
|
|
for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
|
|
|
|
/* Construct the Huffman tree by repeatedly combining the least two
|
|
* frequent nodes.
|
|
*/
|
|
node = elems; /* next internal node of the tree */
|
|
do {
|
|
pqremove(s, tree, n); /* n = node of least frequency */
|
|
m = s->heap[SMALLEST]; /* m = node of next least frequency */
|
|
|
|
s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
|
|
s->heap[--(s->heap_max)] = m;
|
|
|
|
/* Create a new node father of n and m */
|
|
tree[node].Freq = tree[n].Freq + tree[m].Freq;
|
|
s->depth[node] = (uch) (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.
|
|
*/
|
|
static void scan_tree(
|
|
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.
|
|
*/
|
|
static void send_tree(
|
|
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.
|
|
*/
|
|
static int build_bl_tree(
|
|
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.
|
|
*/
|
|
static void send_all_trees(
|
|
deflate_state *s,
|
|
int lcodes, /* number of codes for each tree */
|
|
int dcodes, /* number of codes for each tree */
|
|
int blcodes /* number of codes for each tree */
|
|
)
|
|
{
|
|
int rank; /* index in bl_order */
|
|
|
|
Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
|
|
Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
|
|
"too many codes");
|
|
Tracev((stderr, "\nbl counts: "));
|
|
send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
|
|
send_bits(s, dcodes-1, 5);
|
|
send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */
|
|
for (rank = 0; rank < blcodes; rank++) {
|
|
Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
|
|
send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
|
|
}
|
|
Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
|
|
|
|
send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
|
|
Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
|
|
|
|
send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
|
|
Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
|
|
}
|
|
|
|
/* ===========================================================================
|
|
* Send a stored block
|
|
*/
|
|
void zlib_tr_stored_block(
|
|
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) & (ulg)~7L;
|
|
s->compressed_len += (stored_len + 4) << 3;
|
|
|
|
copy_block(s, buf, (unsigned)stored_len, 1); /* with header */
|
|
}
|
|
|
|
/* Send just the `stored block' type code without any length bytes or data.
|
|
*/
|
|
void zlib_tr_stored_type_only(
|
|
deflate_state *s
|
|
)
|
|
{
|
|
send_bits(s, (STORED_BLOCK << 1), 3);
|
|
bi_windup(s);
|
|
s->compressed_len = (s->compressed_len + 3) & ~7L;
|
|
}
|
|
|
|
|
|
/* ===========================================================================
|
|
* Send one empty static block to give enough lookahead for inflate.
|
|
* This takes 10 bits, of which 7 may remain in the bit buffer.
|
|
* The current inflate code requires 9 bits of lookahead. If the
|
|
* last two codes for the previous block (real code plus EOB) were coded
|
|
* on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode
|
|
* the last real code. In this case we send two empty static blocks instead
|
|
* of one. (There are no problems if the previous block is stored or fixed.)
|
|
* To simplify the code, we assume the worst case of last real code encoded
|
|
* on one bit only.
|
|
*/
|
|
void zlib_tr_align(
|
|
deflate_state *s
|
|
)
|
|
{
|
|
send_bits(s, STATIC_TREES<<1, 3);
|
|
send_code(s, END_BLOCK, static_ltree);
|
|
s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
|
|
bi_flush(s);
|
|
/* Of the 10 bits for the empty block, we have already sent
|
|
* (10 - bi_valid) bits. The lookahead for the last real code (before
|
|
* the EOB of the previous block) was thus at least one plus the length
|
|
* of the EOB plus what we have just sent of the empty static block.
|
|
*/
|
|
if (1 + s->last_eob_len + 10 - s->bi_valid < 9) {
|
|
send_bits(s, STATIC_TREES<<1, 3);
|
|
send_code(s, END_BLOCK, static_ltree);
|
|
s->compressed_len += 10L;
|
|
bi_flush(s);
|
|
}
|
|
s->last_eob_len = 7;
|
|
}
|
|
|
|
/* ===========================================================================
|
|
* Determine the best encoding for the current block: dynamic trees, static
|
|
* trees or store, and output the encoded block to the zip file. This function
|
|
* returns the total compressed length for the file so far.
|
|
*/
|
|
ulg zlib_tr_flush_block(
|
|
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 = 0; /* index of last bit length code of non zero freq */
|
|
|
|
/* Build the Huffman trees unless a stored block is forced */
|
|
if (s->level > 0) {
|
|
|
|
/* Check if the file is ascii or binary */
|
|
if (s->data_type == Z_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;
|
|
|
|
} else {
|
|
Assert(buf != (char*)0, "lost buf");
|
|
opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
|
|
}
|
|
|
|
/* 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 && s->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(s, 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.
|
|
*/
|
|
zlib_tr_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 zlib_tr_tally(
|
|
deflate_state *s,
|
|
unsigned dist, /* distance of matched string */
|
|
unsigned lc /* match length-MIN_MATCH or unmatched char (if dist==0) */
|
|
)
|
|
{
|
|
s->d_buf[s->last_lit] = (ush)dist;
|
|
s->l_buf[s->last_lit++] = (uch)lc;
|
|
if (dist == 0) {
|
|
/* lc is the unmatched char */
|
|
s->dyn_ltree[lc].Freq++;
|
|
} else {
|
|
s->matches++;
|
|
/* Here, lc is the match length - MIN_MATCH */
|
|
dist--; /* dist = match distance - 1 */
|
|
Assert((ush)dist < (ush)MAX_DIST(s) &&
|
|
(ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
|
|
(ush)d_code(dist) < (ush)D_CODES, "zlib_tr_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->last_lit & 0xfff) == 0 && s->level > 2) {
|
|
/* Compute an upper bound for the compressed length */
|
|
ulg out_length = (ulg)s->last_lit*8L;
|
|
ulg in_length = (ulg)((long)s->strstart - s->block_start);
|
|
int dcode;
|
|
for (dcode = 0; dcode < D_CODES; dcode++) {
|
|
out_length += (ulg)s->dyn_dtree[dcode].Freq *
|
|
(5L+extra_dbits[dcode]);
|
|
}
|
|
out_length >>= 3;
|
|
Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
|
|
s->last_lit, in_length, out_length,
|
|
100L - out_length*100L/in_length));
|
|
if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
|
|
}
|
|
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
|
|
*/
|
|
static void compress_block(
|
|
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);
|
|
s->last_eob_len = ltree[END_BLOCK].Len;
|
|
}
|
|
|
|
/* ===========================================================================
|
|
* 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).
|
|
*/
|
|
static void set_data_type(
|
|
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) ? Z_BINARY : Z_ASCII);
|
|
}
|
|
|
|
/* ===========================================================================
|
|
* Copy a stored block, storing first the length and its
|
|
* one's complement if requested.
|
|
*/
|
|
static void copy_block(
|
|
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 */
|
|
s->last_eob_len = 8; /* enough lookahead for inflate */
|
|
|
|
if (header) {
|
|
put_short(s, (ush)len);
|
|
put_short(s, (ush)~len);
|
|
#ifdef DEBUG_ZLIB
|
|
s->bits_sent += 2*16;
|
|
#endif
|
|
}
|
|
#ifdef DEBUG_ZLIB
|
|
s->bits_sent += (ulg)len<<3;
|
|
#endif
|
|
/* bundle up the put_byte(s, *buf++) calls */
|
|
memcpy(&s->pending_buf[s->pending], buf, len);
|
|
s->pending += len;
|
|
}
|
|
|