| /* trees.c -- output deflated data using Huffman coding |
| * Copyright (C) 1995-2017 Jean-loup Gailly |
| * detect_data_type() function provided freely by Cosmin Truta, 2006 |
| * For conditions of distribution and use, see copyright notice in zlib.h |
| */ |
| |
| /* |
| * ALGORITHM |
| * |
| * The "deflation" process uses several Huffman trees. The more |
| * common source values are represented by shorter bit sequences. |
| * |
| * Each code tree is stored in a compressed form which is itself |
| * a Huffman encoding of the lengths of all the code strings (in |
| * ascending order by source values). The actual code strings are |
| * reconstructed from the lengths in the inflate process, as described |
| * in the deflate specification. |
| * |
| * REFERENCES |
| * |
| * Deutsch, L.P.,"'Deflate' Compressed Data Format Specification". |
| * Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc |
| * |
| * Storer, James A. |
| * Data Compression: Methods and Theory, pp. 49-50. |
| * Computer Science Press, 1988. ISBN 0-7167-8156-5. |
| * |
| * Sedgewick, R. |
| * Algorithms, p290. |
| * Addison-Wesley, 1983. ISBN 0-201-06672-6. |
| */ |
| |
| #include "zbuild.h" |
| #include "deflate.h" |
| #include "trees.h" |
| #include "trees_emit.h" |
| #include "trees_tbl.h" |
| |
| /* The lengths of the bit length codes are sent in order of decreasing |
| * probability, to avoid transmitting the lengths for unused bit length codes. |
| */ |
| |
| /* =========================================================================== |
| * Local data. These are initialized only once. |
| */ |
| |
| struct static_tree_desc_s { |
| const ct_data *static_tree; /* static tree or NULL */ |
| const int *extra_bits; /* extra bits for each code or NULL */ |
| int extra_base; /* base index for extra_bits */ |
| int elems; /* max number of elements in the tree */ |
| unsigned int max_length; /* max bit length for the codes */ |
| }; |
| |
| static const static_tree_desc static_l_desc = |
| {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS}; |
| |
| static const static_tree_desc static_d_desc = |
| {static_dtree, extra_dbits, 0, D_CODES, MAX_BITS}; |
| |
| static const static_tree_desc static_bl_desc = |
| {(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS}; |
| |
| /* =========================================================================== |
| * Local (static) routines in this file. |
| */ |
| |
| static void init_block (deflate_state *s); |
| static void pqdownheap (deflate_state *s, ct_data *tree, int k); |
| static void gen_bitlen (deflate_state *s, tree_desc *desc); |
| static void build_tree (deflate_state *s, tree_desc *desc); |
| static void scan_tree (deflate_state *s, ct_data *tree, int max_code); |
| static void send_tree (deflate_state *s, ct_data *tree, int max_code); |
| static int build_bl_tree (deflate_state *s); |
| static void send_all_trees (deflate_state *s, int lcodes, int dcodes, int blcodes); |
| static void compress_block (deflate_state *s, const ct_data *ltree, const ct_data *dtree); |
| static int detect_data_type (deflate_state *s); |
| static void bi_flush (deflate_state *s); |
| |
| /* =========================================================================== |
| * Initialize the tree data structures for a new zlib stream. |
| */ |
| void Z_INTERNAL zng_tr_init(deflate_state *s) { |
| s->l_desc.dyn_tree = s->dyn_ltree; |
| s->l_desc.stat_desc = &static_l_desc; |
| |
| s->d_desc.dyn_tree = s->dyn_dtree; |
| s->d_desc.stat_desc = &static_d_desc; |
| |
| s->bl_desc.dyn_tree = s->bl_tree; |
| s->bl_desc.stat_desc = &static_bl_desc; |
| |
| s->bi_buf = 0; |
| s->bi_valid = 0; |
| #ifdef ZLIB_DEBUG |
| s->compressed_len = 0L; |
| s->bits_sent = 0L; |
| #endif |
| |
| /* Initialize the first block of the first file: */ |
| init_block(s); |
| } |
| |
| /* =========================================================================== |
| * Initialize a new block. |
| */ |
| static void init_block(deflate_state *s) { |
| int n; /* iterates over tree elements */ |
| |
| /* Initialize the trees. */ |
| for (n = 0; n < L_CODES; n++) |
| s->dyn_ltree[n].Freq = 0; |
| for (n = 0; n < D_CODES; n++) |
| s->dyn_dtree[n].Freq = 0; |
| for (n = 0; n < BL_CODES; n++) |
| s->bl_tree[n].Freq = 0; |
| |
| s->dyn_ltree[END_BLOCK].Freq = 1; |
| s->opt_len = s->static_len = 0L; |
| s->sym_next = s->matches = 0; |
| } |
| |
| #define SMALLEST 1 |
| /* Index within the heap array of least frequent node in the Huffman tree */ |
| |
| |
| /* =========================================================================== |
| * Remove the smallest element from the heap and recreate the heap with |
| * one less element. Updates heap and heap_len. |
| */ |
| #define pqremove(s, tree, top) \ |
| {\ |
| top = s->heap[SMALLEST]; \ |
| s->heap[SMALLEST] = s->heap[s->heap_len--]; \ |
| pqdownheap(s, tree, SMALLEST); \ |
| } |
| |
| /* =========================================================================== |
| * Compares to subtrees, using the tree depth as tie breaker when |
| * the subtrees have equal frequency. This minimizes the worst case length. |
| */ |
| #define smaller(tree, n, m, depth) \ |
| (tree[n].Freq < tree[m].Freq || \ |
| (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m])) |
| |
| /* =========================================================================== |
| * Restore the heap property by moving down the tree starting at node k, |
| * exchanging a node with the smallest of its two sons if necessary, stopping |
| * when the heap property is re-established (each father smaller than its |
| * two sons). |
| */ |
| static void pqdownheap(deflate_state *s, ct_data *tree, int k) { |
| /* tree: the tree to restore */ |
| /* k: node to move down */ |
| int v = s->heap[k]; |
| int j = k << 1; /* left son of k */ |
| while (j <= s->heap_len) { |
| /* Set j to the smallest of the two sons: */ |
| if (j < s->heap_len && smaller(tree, s->heap[j+1], s->heap[j], s->depth)) { |
| j++; |
| } |
| /* Exit if v is smaller than both sons */ |
| if (smaller(tree, v, s->heap[j], s->depth)) |
| break; |
| |
| /* Exchange v with the smallest son */ |
| s->heap[k] = s->heap[j]; |
| k = j; |
| |
| /* And continue down the tree, setting j to the left son of k */ |
| j <<= 1; |
| } |
| s->heap[k] = v; |
| } |
| |
| /* =========================================================================== |
| * Compute the optimal bit lengths for a tree and update the total bit length |
| * for the current block. |
| * IN assertion: the fields freq and dad are set, heap[heap_max] and |
| * above are the tree nodes sorted by increasing frequency. |
| * OUT assertions: the field len is set to the optimal bit length, the |
| * array bl_count contains the frequencies for each bit length. |
| * The length opt_len is updated; static_len is also updated if stree is |
| * not null. |
| */ |
| static void gen_bitlen(deflate_state *s, tree_desc *desc) { |
| /* desc: the tree descriptor */ |
| ct_data *tree = desc->dyn_tree; |
| int max_code = desc->max_code; |
| const ct_data *stree = desc->stat_desc->static_tree; |
| const int *extra = desc->stat_desc->extra_bits; |
| int base = desc->stat_desc->extra_base; |
| unsigned int max_length = desc->stat_desc->max_length; |
| int h; /* heap index */ |
| int n, m; /* iterate over the tree elements */ |
| unsigned int bits; /* bit length */ |
| int xbits; /* extra bits */ |
| uint16_t f; /* frequency */ |
| int overflow = 0; /* number of elements with bit length too large */ |
| |
| for (bits = 0; bits <= MAX_BITS; bits++) |
| s->bl_count[bits] = 0; |
| |
| /* In a first pass, compute the optimal bit lengths (which may |
| * overflow in the case of the bit length tree). |
| */ |
| tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */ |
| |
| for (h = s->heap_max + 1; h < HEAP_SIZE; h++) { |
| n = s->heap[h]; |
| bits = tree[tree[n].Dad].Len + 1u; |
| if (bits > max_length){ |
| bits = max_length; |
| overflow++; |
| } |
| tree[n].Len = (uint16_t)bits; |
| /* We overwrite tree[n].Dad which is no longer needed */ |
| |
| if (n > max_code) /* not a leaf node */ |
| continue; |
| |
| s->bl_count[bits]++; |
| xbits = 0; |
| if (n >= base) |
| xbits = extra[n-base]; |
| f = tree[n].Freq; |
| s->opt_len += (unsigned long)f * (unsigned int)(bits + xbits); |
| if (stree) |
| s->static_len += (unsigned long)f * (unsigned int)(stree[n].Len + xbits); |
| } |
| if (overflow == 0) |
| return; |
| |
| Tracev((stderr, "\nbit length overflow\n")); |
| /* This happens for example on obj2 and pic of the Calgary corpus */ |
| |
| /* Find the first bit length which could increase: */ |
| do { |
| bits = max_length - 1; |
| while (s->bl_count[bits] == 0) |
| bits--; |
| s->bl_count[bits]--; /* move one leaf down the tree */ |
| s->bl_count[bits+1] += 2u; /* move one overflow item as its brother */ |
| s->bl_count[max_length]--; |
| /* The brother of the overflow item also moves one step up, |
| * but this does not affect bl_count[max_length] |
| */ |
| overflow -= 2; |
| } while (overflow > 0); |
| |
| /* 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 != bits) { |
| Tracev((stderr, "code %d bits %d->%u\n", m, tree[m].Len, bits)); |
| s->opt_len += (unsigned long)(bits * tree[m].Freq); |
| s->opt_len -= (unsigned long)(tree[m].Len * tree[m].Freq); |
| tree[m].Len = (uint16_t)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. |
| */ |
| Z_INTERNAL void gen_codes(ct_data *tree, int max_code, uint16_t *bl_count) { |
| /* tree: the tree to decorate */ |
| /* max_code: largest code with non zero frequency */ |
| /* bl_count: number of codes at each bit length */ |
| uint16_t next_code[MAX_BITS+1]; /* next code value for each bit length */ |
| unsigned int 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++) { |
| code = (code + bl_count[bits-1]) << 1; |
| next_code[bits] = (uint16_t)code; |
| } |
| /* 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 = (uint16_t)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) { |
| /* 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] = (unsigned char)((s->depth[n] >= s->depth[m] ? |
| s->depth[n] : s->depth[m]) + 1); |
| tree[n].Dad = tree[m].Dad = (uint16_t)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, int max_code) { |
| /* tree: the tree to be scanned */ |
| /* 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 */ |
| uint16_t count = 0; /* repeat count of the current code */ |
| uint16_t max_count = 7; /* max repeat count */ |
| uint16_t min_count = 4; /* min repeat count */ |
| |
| if (nextlen == 0) |
| max_count = 138, min_count = 3; |
| |
| tree[max_code+1].Len = (uint16_t)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, int max_code) { |
| /* tree: the tree to be scanned */ |
| /* 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; |
| |
| // Temp local variables |
| uint32_t bi_valid = s->bi_valid; |
| uint64_t bi_buf = s->bi_buf; |
| |
| 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, bi_buf, bi_valid); |
| } while (--count != 0); |
| |
| } else if (curlen != 0) { |
| if (curlen != prevlen) { |
| send_code(s, curlen, s->bl_tree, bi_buf, bi_valid); |
| count--; |
| } |
| Assert(count >= 3 && count <= 6, " 3_6?"); |
| send_code(s, REP_3_6, s->bl_tree, bi_buf, bi_valid); |
| send_bits(s, count-3, 2, bi_buf, bi_valid); |
| |
| } else if (count <= 10) { |
| send_code(s, REPZ_3_10, s->bl_tree, bi_buf, bi_valid); |
| send_bits(s, count-3, 3, bi_buf, bi_valid); |
| |
| } else { |
| send_code(s, REPZ_11_138, s->bl_tree, bi_buf, bi_valid); |
| send_bits(s, count-11, 7, bi_buf, bi_valid); |
| } |
| 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; |
| } |
| } |
| |
| // Store back temp variables |
| s->bi_buf = bi_buf; |
| s->bi_valid = bi_valid; |
| } |
| |
| /* =========================================================================== |
| * 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*((unsigned long)max_blindex+1) + 5+5+4; |
| Tracev((stderr, "\ndyn trees: dyn %lu, stat %lu", 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, int dcodes, int blcodes) { |
| 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"); |
| |
| // Temp local variables |
| uint32_t bi_valid = s->bi_valid; |
| uint64_t bi_buf = s->bi_buf; |
| |
| Tracev((stderr, "\nbl counts: ")); |
| send_bits(s, lcodes-257, 5, bi_buf, bi_valid); /* not +255 as stated in appnote.txt */ |
| send_bits(s, dcodes-1, 5, bi_buf, bi_valid); |
| send_bits(s, blcodes-4, 4, bi_buf, bi_valid); /* not -3 as stated in appnote.txt */ |
| for (rank = 0; rank < blcodes; rank++) { |
| Tracev((stderr, "\nbl code %2u ", bl_order[rank])); |
| send_bits(s, s->bl_tree[bl_order[rank]].Len, 3, bi_buf, bi_valid); |
| } |
| Tracev((stderr, "\nbl tree: sent %lu", s->bits_sent)); |
| |
| // Store back temp variables |
| s->bi_buf = bi_buf; |
| s->bi_valid = bi_valid; |
| |
| send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */ |
| Tracev((stderr, "\nlit tree: sent %lu", s->bits_sent)); |
| |
| send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */ |
| Tracev((stderr, "\ndist tree: sent %lu", s->bits_sent)); |
| } |
| |
| /* =========================================================================== |
| * Send a stored block |
| */ |
| void Z_INTERNAL zng_tr_stored_block(deflate_state *s, char *buf, uint32_t stored_len, int last) { |
| /* buf: input block */ |
| /* stored_len: length of input block */ |
| /* last: one if this is the last block for a file */ |
| zng_tr_emit_tree(s, STORED_BLOCK, last); /* send block type */ |
| zng_tr_emit_align(s); /* align on byte boundary */ |
| cmpr_bits_align(s); |
| put_short(s, (uint16_t)stored_len); |
| put_short(s, (uint16_t)~stored_len); |
| cmpr_bits_add(s, 32); |
| sent_bits_add(s, 32); |
| if (stored_len) { |
| memcpy(s->pending_buf + s->pending, (unsigned char *)buf, stored_len); |
| s->pending += stored_len; |
| cmpr_bits_add(s, stored_len << 3); |
| sent_bits_add(s, stored_len << 3); |
| } |
| } |
| |
| /* =========================================================================== |
| * Flush the bits in the bit buffer to pending output (leaves at most 7 bits) |
| */ |
| void Z_INTERNAL zng_tr_flush_bits(deflate_state *s) { |
| bi_flush(s); |
| } |
| |
| /* =========================================================================== |
| * Send one empty static block to give enough lookahead for inflate. |
| * This takes 10 bits, of which 7 may remain in the bit buffer. |
| */ |
| void Z_INTERNAL zng_tr_align(deflate_state *s) { |
| zng_tr_emit_tree(s, STATIC_TREES, 0); |
| zng_tr_emit_end_block(s, static_ltree, 0); |
| bi_flush(s); |
| } |
| |
| /* =========================================================================== |
| * Determine the best encoding for the current block: dynamic trees, static |
| * trees or store, and write out the encoded block. |
| */ |
| void Z_INTERNAL zng_tr_flush_block(deflate_state *s, char *buf, uint32_t stored_len, int last) { |
| /* buf: input block, or NULL if too old */ |
| /* stored_len: length of input block */ |
| /* last: one if this is the last block for a file */ |
| unsigned long 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 (UNLIKELY(s->sym_next == 0)) { |
| /* Emit an empty static tree block with no codes */ |
| opt_lenb = static_lenb = 0; |
| s->static_len = 7; |
| } else if (s->level > 0) { |
| /* Check if the file is binary or text */ |
| if (s->strm->data_type == Z_UNKNOWN) |
| s->strm->data_type = detect_data_type(s); |
| |
| /* Construct the literal and distance trees */ |
| build_tree(s, (tree_desc *)(&(s->l_desc))); |
| Tracev((stderr, "\nlit data: dyn %lu, stat %lu", s->opt_len, s->static_len)); |
| |
| build_tree(s, (tree_desc *)(&(s->d_desc))); |
| Tracev((stderr, "\ndist data: dyn %lu, stat %lu", 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 the block lengths 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 %u lit %u ", |
| opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len, |
| s->sym_next / 3)); |
| |
| if (static_lenb <= opt_lenb) |
| opt_lenb = static_lenb; |
| |
| } else { |
| Assert(buf != NULL, "lost buf"); |
| opt_lenb = static_lenb = stored_len + 5; /* force a stored block */ |
| } |
| |
| if (stored_len+4 <= opt_lenb && buf != NULL) { |
| /* 4: two words for the lengths |
| * 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. |
| */ |
| zng_tr_stored_block(s, buf, stored_len, last); |
| |
| } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) { |
| zng_tr_emit_tree(s, STATIC_TREES, last); |
| compress_block(s, (const ct_data *)static_ltree, (const ct_data *)static_dtree); |
| cmpr_bits_add(s, s->static_len); |
| } else { |
| zng_tr_emit_tree(s, DYN_TREES, last); |
| send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1, max_blindex+1); |
| compress_block(s, (const ct_data *)s->dyn_ltree, (const ct_data *)s->dyn_dtree); |
| cmpr_bits_add(s, s->opt_len); |
| } |
| Assert(s->compressed_len == s->bits_sent, "bad compressed size"); |
| /* The above check is made mod 2^32, for files larger than 512 MB |
| * and unsigned long implemented on 32 bits. |
| */ |
| init_block(s); |
| |
| if (last) { |
| zng_tr_emit_align(s); |
| } |
| Tracev((stderr, "\ncomprlen %lu(%lu) ", s->compressed_len>>3, s->compressed_len-7*last)); |
| } |
| |
| /* =========================================================================== |
| * Send the block data compressed using the given Huffman trees |
| */ |
| static void compress_block(deflate_state *s, const ct_data *ltree, const ct_data *dtree) { |
| /* ltree: literal tree */ |
| /* dtree: distance tree */ |
| unsigned dist; /* distance of matched string */ |
| int lc; /* match length or unmatched char (if dist == 0) */ |
| unsigned sx = 0; /* running index in sym_buf */ |
| |
| if (s->sym_next != 0) { |
| do { |
| dist = s->sym_buf[sx++] & 0xff; |
| dist += (unsigned)(s->sym_buf[sx++] & 0xff) << 8; |
| lc = s->sym_buf[sx++]; |
| if (dist == 0) { |
| zng_emit_lit(s, ltree, lc); |
| } else { |
| zng_emit_dist(s, ltree, dtree, lc, dist); |
| } /* literal or match pair ? */ |
| |
| /* Check that the overlay between pending_buf and sym_buf is ok: */ |
| Assert(s->pending < s->lit_bufsize + sx, "pending_buf overflow"); |
| } while (sx < s->sym_next); |
| } |
| |
| zng_emit_end_block(s, ltree, 0); |
| } |
| |
| /* =========================================================================== |
| * Check if the data type is TEXT or BINARY, using the following algorithm: |
| * - TEXT if the two conditions below are satisfied: |
| * a) There are no non-portable control characters belonging to the |
| * "black list" (0..6, 14..25, 28..31). |
| * b) There is at least one printable character belonging to the |
| * "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255). |
| * - BINARY otherwise. |
| * - The following partially-portable control characters form a |
| * "gray list" that is ignored in this detection algorithm: |
| * (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}). |
| * IN assertion: the fields Freq of dyn_ltree are set. |
| */ |
| static int detect_data_type(deflate_state *s) { |
| /* black_mask is the bit mask of black-listed bytes |
| * set bits 0..6, 14..25, and 28..31 |
| * 0xf3ffc07f = binary 11110011111111111100000001111111 |
| */ |
| unsigned long black_mask = 0xf3ffc07fUL; |
| int n; |
| |
| /* Check for non-textual ("black-listed") bytes. */ |
| for (n = 0; n <= 31; n++, black_mask >>= 1) |
| if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0)) |
| return Z_BINARY; |
| |
| /* Check for textual ("white-listed") bytes. */ |
| if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0 || s->dyn_ltree[13].Freq != 0) |
| return Z_TEXT; |
| for (n = 32; n < LITERALS; n++) |
| if (s->dyn_ltree[n].Freq != 0) |
| return Z_TEXT; |
| |
| /* There are no "black-listed" or "white-listed" bytes: |
| * this stream either is empty or has tolerated ("gray-listed") bytes only. |
| */ |
| return Z_BINARY; |
| } |
| |
| /* =========================================================================== |
| * Flush the bit buffer, keeping at most 7 bits in it. |
| */ |
| static void bi_flush(deflate_state *s) { |
| if (s->bi_valid == 64) { |
| put_uint64(s, s->bi_buf); |
| s->bi_buf = 0; |
| s->bi_valid = 0; |
| } else { |
| if (s->bi_valid >= 32) { |
| put_uint32(s, (uint32_t)s->bi_buf); |
| s->bi_buf >>= 32; |
| s->bi_valid -= 32; |
| } |
| if (s->bi_valid >= 16) { |
| put_short(s, (uint16_t)s->bi_buf); |
| s->bi_buf >>= 16; |
| s->bi_valid -= 16; |
| } |
| if (s->bi_valid >= 8) { |
| put_byte(s, s->bi_buf); |
| s->bi_buf >>= 8; |
| s->bi_valid -= 8; |
| } |
| } |
| } |
| |
| /* =========================================================================== |
| * Reverse the first len bits of a code, using straightforward code (a faster |
| * method would use a table) |
| * IN assertion: 1 <= len <= 15 |
| */ |
| Z_INTERNAL unsigned bi_reverse(unsigned code, int len) { |
| /* code: the value to invert */ |
| /* len: its bit length */ |
| Z_REGISTER unsigned res = 0; |
| do { |
| res |= code & 1; |
| code >>= 1, res <<= 1; |
| } while (--len > 0); |
| return res >> 1; |
| } |
