808 lines
29 KiB
C++
808 lines
29 KiB
C++
// ztrees.cpp - modified by Wei Dai from:
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// Distributed with Jean-loup Gailly's permission.
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/*
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The following sorce code is derived from Info-Zip 'zip' 2.01
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distribution copyrighted by Mark Adler, Richard B. Wales,
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Jean-loup Gailly, Kai Uwe Rommel, Igor Mandrichenko and John Bush.
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*/
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/*
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* trees.c by Jean-loup Gailly
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*
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* This is a new version of im_ctree.c originally written by Richard B. Wales
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* for the defunct implosion method.
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*
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* PURPOSE
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*
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* Encode various sets of source values using variable-length
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* binary code trees.
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*
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* DISCUSSION
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*
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* The PKZIP "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 the ZIP file in a compressed form
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* which is itself a Huffman encoding of the lengths of
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* all the code strings (in ascending order by source values).
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* The actual code strings are reconstructed from the lengths in
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* the UNZIP process, as described in the "application note"
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* (APPNOTE.TXT) distributed as part of PKWARE's PKZIP program.
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*
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* REFERENCES
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*
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* Lynch, Thomas J.
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* Data Compression: Techniques and Applications, pp. 53-55.
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* Lifetime Learning Publications, 1985. ISBN 0-534-03418-7.
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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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* INTERFACE
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*
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* int ct_init (void)
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* Allocate the match buffer and initialize the various tables.
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*
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* int ct_tally(int dist, int lc);
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* Save the match info and tally the frequency counts.
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* Return true if the current block must be flushed.
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*
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* long flush_block (char *buf, ulg stored_len, int eof)
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* Determine the best encoding for the current block: dynamic trees,
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* static trees or store, and output the encoded block to the zip
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* file. Returns the total compressed length for the file so far.
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*/
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#include "pch.h"
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#include "ztrees.h"
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bool CodeTree::streesBuilt = false;
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CodeTree::ct_data CodeTree::static_ltree[CodeTree::L_CODES+2];
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CodeTree::ct_data CodeTree::static_dtree[CodeTree::D_CODES];
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const int CodeTree::extra_lbits[] /* 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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const int CodeTree::extra_dbits[] /* 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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const int CodeTree::extra_blbits[]/* 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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const uint8_t CodeTree::bl_order[]
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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 send_code(c, tree) send_bits(tree[(unsigned int)c].Code, tree[(unsigned int)c].Len)
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/* Send a code of the given tree. c and tree must not have side effects */
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#define d_code(dist) \
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((dist) < 256 ? dist_code[(unsigned int)dist] : dist_code[(unsigned int)(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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static unsigned reverse(unsigned int code, int len)
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/* Reverse the first len bits of a code. */
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{
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unsigned res = 0;
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do res = (res << 1) | (code & 1), code>>=1; while (--len);
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return res;
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}
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/* Allocate the match buffer and initialize the various tables. */
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CodeTree::CodeTree(int deflate_level, BufferedTransformation &outQ)
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: BitOutput(outQ),
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deflate_level(deflate_level),
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dyn_ltree(HEAP_SIZE), dyn_dtree(2*D_CODES+1),
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bl_tree(2*BL_CODES+1),
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bl_count(MAX_BITS+1),
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l_desc(dyn_ltree, static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS, 0),
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d_desc(dyn_dtree, static_dtree, extra_dbits, 0, D_CODES, MAX_BITS, 0),
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bl_desc(bl_tree, (ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS, 0),
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heap(2*L_CODES+1),
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depth(2*L_CODES+1),
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length_code(MAX_MATCH-MIN_MATCH+1),
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dist_code(512),
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base_length(LENGTH_CODES),
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base_dist(D_CODES),
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l_buf(LIT_BUFSIZE),
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d_buf(DIST_BUFSIZE),
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flag_buf(LIT_BUFSIZE/8)
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{
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unsigned int n; /* iterates over tree elements */
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unsigned int bits; /* bit counter */
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unsigned int length; /* length value */
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unsigned int code; /* code value */
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unsigned int dist; /* distance index */
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compressed_len = input_len = 0L;
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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 < (1U<<extra_lbits[code]); n++) {
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length_code[length++] = (uint8_t)code;
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}
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}
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assert (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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length_code[length-1] = (uint8_t)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 < (1U<<extra_dbits[code]); n++) {
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dist_code[dist++] = (uint8_t)code;
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}
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}
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assert (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 < (1U<<(extra_dbits[code]-7)); n++) {
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dist_code[256 + dist++] = (uint8_t)code;
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}
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}
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assert (dist == 256);
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if (!streesBuilt)
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{
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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[(unsigned int)8]++;
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while (n <= 255) static_ltree[n++].Len = 9, bl_count[(unsigned int)9]++;
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while (n <= 279) static_ltree[n++].Len = 7, bl_count[(unsigned int)7]++;
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while (n <= 287) static_ltree[n++].Len = 8, bl_count[(unsigned int)8]++;
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/* Codes 286 and 287 do not exist, but we must include them in the tree
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construction to get a canonical Huffman tree (longest code all ones) */
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gen_codes(static_ltree, L_CODES+1);
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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 = reverse(n, 5);
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}
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streesBuilt = true;
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}
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/* Initialize the first block of the first file: */
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init_block();
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}
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/* Initialize a new block. */
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void CodeTree::init_block()
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{
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unsigned int n; /* iterates over tree elements */
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/* Initialize the trees. */
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for (n=0; n < L_CODES; n++) dyn_ltree[n].Freq = 0;
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for (n=0; n < D_CODES; n++) dyn_dtree[n].Freq = 0;
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for (n=0; n < BL_CODES; n++) bl_tree[n].Freq = 0;
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dyn_ltree[(unsigned int)END_BLOCK].Freq = 1;
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opt_len = static_len = 0L;
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last_lit = last_dist = last_flags = 0;
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flags = 0; flag_bit = 1;
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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(tree, top) \
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{\
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top = heap[(unsigned int)SMALLEST]; \
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heap[(unsigned int)SMALLEST] = heap[(unsigned int)heap_len--]; \
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pqdownheap(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) \
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(tree[(unsigned int)n].Freq < tree[(unsigned int)m].Freq || \
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(tree[(unsigned int)n].Freq == tree[(unsigned int)m].Freq && depth[(unsigned int)n] <= depth[(unsigned int)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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void CodeTree::pqdownheap(ct_data *tree, int k)
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{
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unsigned int kk = (unsigned int) k;
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int v = heap[kk];
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unsigned int j = kk << 1; /* left son of k */
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int htemp; /* required because of bug in SASC compiler */
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while (j <= (unsigned int)heap_len) {
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/* Set j to the smallest of the two sons: */
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if (j < (unsigned int)heap_len && smaller(tree, heap[(unsigned int)(j+1)], heap[(unsigned int)j])) j++;
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/* Exit if v is smaller than both sons */
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htemp = heap[j];
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if (smaller(tree, v, htemp)) break;
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/* Exchange v with the smallest son */
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heap[(unsigned int)k] = htemp;
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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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heap[(unsigned int)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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void CodeTree::gen_bitlen(tree_desc *desc)
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{
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ct_data *tree = desc->dyn_tree;
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const int *extra = desc->extra_bits;
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int base = desc->extra_base;
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int max_code = desc->max_code;
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int max_length = desc->max_length;
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const ct_data *stree = desc->static_tree;
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unsigned int h; /* heap index */
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int n, m; /* iterate over the tree elements */
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unsigned int bits; /* bit length */
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int xbits; /* extra bits */
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word16 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++) 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[heap[(unsigned int)heap_max]].Len = 0; /* root of the heap */
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for (h = heap_max+1; h < HEAP_SIZE; h++) {
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n = heap[h];
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bits = tree[tree[n].Dad].Len + 1;
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if (bits > (unsigned int)max_length) bits = max_length, overflow++;
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tree[n].Len = 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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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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opt_len += (word32)f * (bits + xbits);
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if (stree) static_len += (word32)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 (bl_count[bits] == 0) bits--;
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bl_count[bits]--; /* move one leaf down the tree */
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bl_count[bits+1] += 2; /* move one overflow item as its brother */
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bl_count[(unsigned int)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.
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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 = bl_count[bits];
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while (n != 0) {
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m = 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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opt_len += ((long)bits-(long)tree[m].Len)*(long)tree[m].Freq;
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tree[m].Len = 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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* 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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void CodeTree::gen_codes (ct_data *tree, int max_code)
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{
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word16 next_code[MAX_BITS+1]; /* next code value for each bit length */
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word16 code = 0; /* running code value */
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unsigned int bits; /* bit index */
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int n; /* code index */
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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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// Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
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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 = reverse(next_code[len]++, len);
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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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* 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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void CodeTree::build_tree(tree_desc *desc)
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{
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ct_data *tree = desc->dyn_tree;
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const ct_data *stree = desc->static_tree;
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int elems = 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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/* 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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heap_len = 0, heap_max = HEAP_SIZE;
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for (n = 0; n < elems; n++) {
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if (tree[n].Freq != 0) {
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heap[(unsigned int)++heap_len] = max_code = n;
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depth[(unsigned int)n] = 0;
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} else {
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tree[n].Len = 0;
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}
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}
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/* The pkzip format requires that at least one distance code exists,
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* and that at least one bit should be sent even if there is only one
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* possible code. So to avoid special checks later on we force at least
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* two codes of non zero frequency.
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*/
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while (heap_len < 2) {
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int _new = heap[(unsigned int)++heap_len] = (max_code < 2 ? ++max_code : 0);
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tree[_new].Freq = 1;
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depth[(unsigned int)_new] = 0;
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opt_len--; if (stree) static_len -= stree[_new].Len;
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/* new is 0 or 1 so it does not have extra bits */
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}
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desc->max_code = max_code;
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/* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
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* establish sub-heaps of increasing lengths:
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*/
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for (n = heap_len/2; n >= 1; n--) pqdownheap(tree, n);
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/* Construct the Huffman tree by repeatedly combining the least two
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* frequent nodes.
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*/
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do {
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pqremove(tree, n); /* n = node of least frequency */
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m = heap[(unsigned int)SMALLEST]; /* m = node of next least frequency */
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heap[(unsigned int)--heap_max] = n; /* keep the nodes sorted by frequency */
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heap[(unsigned int)--heap_max] = m;
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/* Create a new node father of n and m */
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tree[node].Freq = tree[n].Freq + tree[m].Freq;
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depth[(unsigned int)node] = (uint8_t) (MAX(depth[(unsigned int)n], depth[(unsigned int)m]) + 1);
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tree[n].Dad = tree[m].Dad = node;
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#ifdef DUMP_BL_TREE
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if (tree == 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 */
|
|
heap[(unsigned int)SMALLEST] = node++;
|
|
pqdownheap(tree, SMALLEST);
|
|
|
|
} while (heap_len >= 2);
|
|
|
|
heap[(unsigned int)--heap_max] = heap[(unsigned int)SMALLEST];
|
|
|
|
/* At this point, the fields freq and dad are set. We can now
|
|
* generate the bit lengths.
|
|
*/
|
|
gen_bitlen(desc);
|
|
|
|
/* The field len is now set, we can generate the bit codes */
|
|
gen_codes (tree, max_code);
|
|
}
|
|
|
|
/* ===========================================================================
|
|
* Scan a literal or distance tree to determine the frequencies of the codes
|
|
* in the bit length tree. Updates opt_len to take into account the repeat
|
|
* counts. (The contribution of the bit length codes will be added later
|
|
* during the construction of bl_tree.)
|
|
*/
|
|
void CodeTree::scan_tree (ct_data *tree, int max_code)
|
|
{
|
|
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 = (word16)-1; /* 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) {
|
|
bl_tree[(unsigned int)curlen].Freq += count;
|
|
} else if (curlen != 0) {
|
|
if (curlen != prevlen) bl_tree[(unsigned int)curlen].Freq++;
|
|
bl_tree[(unsigned int)REP_3_6].Freq++;
|
|
} else if (count <= 10) {
|
|
bl_tree[(unsigned int)REPZ_3_10].Freq++;
|
|
} else {
|
|
bl_tree[(unsigned int)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. */
|
|
void CodeTree::send_tree (ct_data *tree, int max_code)
|
|
{
|
|
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(curlen, bl_tree);
|
|
} while (--count != 0);
|
|
} else if (curlen != 0) {
|
|
if (curlen != prevlen) {
|
|
send_code(curlen, bl_tree);
|
|
count--;
|
|
}
|
|
assert(count >= 3 && count <= 6);
|
|
send_code(REP_3_6, bl_tree);
|
|
send_bits(count-3, 2);
|
|
} else if (count <= 10) {
|
|
send_code(REPZ_3_10, bl_tree);
|
|
send_bits(count-3, 3);
|
|
} else {
|
|
send_code(REPZ_11_138, bl_tree);
|
|
send_bits(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. */
|
|
int CodeTree::build_bl_tree()
|
|
{
|
|
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(dyn_ltree, l_desc.max_code);
|
|
scan_tree(dyn_dtree, d_desc.max_code);
|
|
|
|
/* Build the bit length tree: */
|
|
build_tree(&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 (bl_tree[(unsigned int)bl_order[max_blindex]].Len != 0) break;
|
|
}
|
|
/* Update opt_len to include the bit length tree and counts */
|
|
opt_len += 3*(max_blindex+1) + 5+5+4;
|
|
// Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", opt_len, 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. */
|
|
void CodeTree::send_all_trees(int lcodes, int dcodes, int blcodes)
|
|
{
|
|
int rank; /* index in bl_order */
|
|
|
|
assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4);
|
|
assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES);
|
|
// Tracev((stderr, "\nbl counts: "));
|
|
send_bits(lcodes-257, 5);
|
|
/* not +255 as stated in appnote.txt 1.93a or -256 in 2.04c */
|
|
send_bits(dcodes-1, 5);
|
|
/* not -3 as stated in appnote.txt */
|
|
send_bits(blcodes-4, 4);
|
|
for (rank = 0; rank < blcodes; rank++) {
|
|
// Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
|
|
send_bits(bl_tree[(unsigned int)bl_order[rank]].Len, 3);
|
|
}
|
|
// Tracev((stderr, "\nbl tree: sent %ld", bits_sent));
|
|
|
|
/* send the literal tree */
|
|
send_tree(dyn_ltree, lcodes-1);
|
|
// Tracev((stderr, "\nlit tree: sent %ld", bits_sent));
|
|
|
|
/* send the distance tree */
|
|
send_tree(dyn_dtree, dcodes-1);
|
|
// Tracev((stderr, "\ndist tree: sent %ld", bits_sent));
|
|
}
|
|
|
|
/* ===========================================================================
|
|
* 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.
|
|
*/
|
|
word32 CodeTree::flush_block(uint8_t *buf, word32 stored_len, int eof)
|
|
{
|
|
word32 opt_lenb, static_lenb; /* opt_len and static_len in bytes */
|
|
int max_blindex; /* index of last bit length code of non zero freq */
|
|
|
|
flag_buf[last_flags] = flags; /* Save the flags for the last 8 items */
|
|
|
|
/* Construct the literal and distance trees */
|
|
build_tree(&l_desc);
|
|
// Tracev((stderr, "\nlit data: dyn %ld, stat %ld", opt_len, static_len));
|
|
|
|
build_tree(&d_desc);
|
|
// Tracev((stderr, "\ndist data: dyn %ld, stat %ld", opt_len, 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();
|
|
|
|
/* Determine the best encoding. Compute first the block length in bytes */
|
|
opt_lenb = (opt_len+3+7)>>3;
|
|
static_lenb = (static_len+3+7)>>3;
|
|
input_len += stored_len; /* for debugging only */
|
|
|
|
// Trace((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ",
|
|
// opt_lenb, opt_len, static_lenb, static_len, stored_len,
|
|
// last_lit, last_dist));
|
|
|
|
if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
|
|
|
|
#ifdef FORCE_METHOD
|
|
if (level == 2 && buf) /* force stored block */
|
|
#else
|
|
if (stored_len+4 <= opt_lenb && buf) /* 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.
|
|
*/
|
|
/* send block type */
|
|
send_bits((STORED_BLOCK<<1)+eof, 3);
|
|
compressed_len = (compressed_len + 3 + 7) & ~7L;
|
|
compressed_len += (stored_len + 4) << 3;
|
|
/* with header */
|
|
copy_block(buf, (unsigned)stored_len, 1);
|
|
}
|
|
#ifdef FORCE_METHOD
|
|
else if (level == 3) /* force static trees */
|
|
#else
|
|
else if (static_lenb == opt_lenb)
|
|
#endif
|
|
{
|
|
send_bits((STATIC_TREES<<1)+eof, 3);
|
|
compress_block(static_ltree,static_dtree);
|
|
compressed_len += 3 + static_len;
|
|
} else {
|
|
send_bits((DYN_TREES<<1)+eof, 3);
|
|
send_all_trees(l_desc.max_code+1, d_desc.max_code+1, max_blindex+1);
|
|
compress_block(dyn_ltree,dyn_dtree);
|
|
compressed_len += 3 + opt_len;
|
|
}
|
|
// assert (compressed_len == bits_sent);
|
|
init_block();
|
|
|
|
if (eof) {
|
|
// assert (input_len == isize);
|
|
bi_windup();
|
|
compressed_len += 7; /* align on byte boundary */
|
|
}
|
|
// Tracev((stderr,"\ncomprlen %lu(%lu) ", compressed_len>>3,
|
|
// compressed_len-7*eof));
|
|
|
|
return compressed_len >> 3;
|
|
}
|
|
|
|
/* Save the match info and tally the frequency counts.
|
|
Return true if the current block must be flushed. */
|
|
int CodeTree::ct_tally (int dist, int lc)
|
|
{
|
|
l_buf[last_lit++] = (uint8_t)lc;
|
|
if (dist == 0) {
|
|
/* lc is the unmatched char */
|
|
dyn_ltree[(unsigned int)lc].Freq++;
|
|
} else {
|
|
/* Here, lc is the match length - MIN_MATCH */
|
|
dist--; /* dist = match distance - 1 */
|
|
assert((word16)dist < (word16)MAX_DIST &&
|
|
(word16)lc <= (word16)(MAX_MATCH-MIN_MATCH) &&
|
|
(word16)d_code(dist) < (word16)D_CODES);
|
|
|
|
dyn_ltree[(unsigned int)length_code[(unsigned int)lc]+LITERALS+1].Freq++;
|
|
dyn_dtree[(unsigned int)d_code(dist)].Freq++;
|
|
|
|
d_buf[last_dist++] = dist;
|
|
flags |= flag_bit;
|
|
}
|
|
flag_bit <<= 1;
|
|
|
|
/* Output the flags if they fill a byte: */
|
|
if ((last_lit & 7) == 0) {
|
|
flag_buf[last_flags++] = flags;
|
|
flags = 0, flag_bit = 1;
|
|
}
|
|
/* Try to guess if it is profitable to stop the current block here */
|
|
if (deflate_level > 2 && (last_lit & 0xfff) == 0) {
|
|
/* Compute an upper bound for the compressed length */
|
|
word32 out_length = (word32)last_lit*8L;
|
|
word32 in_length = (word32)strstart-block_start;
|
|
unsigned int dcode;
|
|
for (dcode = 0; dcode < D_CODES; dcode++) {
|
|
out_length += (word32)dyn_dtree[dcode].Freq*(5L+extra_dbits[dcode]);
|
|
}
|
|
out_length >>= 3;
|
|
// Trace((stderr,"\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ",
|
|
// last_lit, last_dist, in_length, out_length,
|
|
// 100L - out_length*100L/in_length));
|
|
if (last_dist < last_lit/2 && out_length < in_length/2) return 1;
|
|
}
|
|
return (last_lit == LIT_BUFSIZE-1 || last_dist == (unsigned)DIST_BUFSIZE);
|
|
/* 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 */
|
|
void CodeTree::compress_block(ct_data *ltree, ct_data *dtree)
|
|
{
|
|
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 dx = 0; /* running index in d_buf */
|
|
unsigned fx = 0; /* running index in flag_buf */
|
|
uint8_t flag = 0; /* current flags */
|
|
unsigned code; /* the code to send */
|
|
int extra; /* number of extra bits to send */
|
|
|
|
if (last_lit != 0)
|
|
do {
|
|
if ((lx & 7) == 0) flag = flag_buf[fx++];
|
|
lc = l_buf[lx++];
|
|
if ((flag & 1) == 0) {
|
|
/* send a literal byte */
|
|
send_code(lc, ltree);
|
|
// Tracecv(isgraph(lc), (stderr," '%c' ", lc));
|
|
} else {
|
|
/* Here, lc is the match length - MIN_MATCH */
|
|
code = length_code[(unsigned int)lc];
|
|
/* send the length code */
|
|
send_code(code+LITERALS+1, ltree);
|
|
if ((extra = extra_lbits[code]) != 0) {
|
|
lc -= base_length[code];
|
|
/* send the extra length bits */
|
|
send_bits(lc, extra);
|
|
}
|
|
dist = d_buf[dx++];
|
|
/* Here, dist is the match distance - 1 */
|
|
code = d_code(dist);
|
|
assert(code < D_CODES);
|
|
|
|
/* send the distance code */
|
|
send_code(code, dtree);
|
|
if ((extra = extra_dbits[code]) != 0) {
|
|
dist -= base_dist[code];
|
|
/* send the extra distance bits */
|
|
send_bits(dist, extra);
|
|
}
|
|
} /* literal or match pair ? */
|
|
flag >>= 1;
|
|
} while (lx < last_lit);
|
|
|
|
send_code(END_BLOCK, ltree);
|
|
}
|