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opencv/3rdparty/zlib-ng/trees.c

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/* trees.c -- output deflated data using Huffman coding
* Copyright (C) 1995-2021 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 = PREFIX(bi_reverse)(next_code[len]++, len);
Tracecv(tree != static_ltree, (stderr, "\nn %3d %c l %2d c %4x (%x) ",
n, (isgraph(n & 0xff) ? 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 || s->strategy == Z_FIXED)
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 (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 bit manipulation
*/
Z_INTERNAL uint16_t PREFIX(bi_reverse)(unsigned code, int len) {
/* code: the value to invert */
/* len: its bit length */
Assert(len >= 1 && len <= 15, "code length must be 1-15");
#define bitrev8(b) \
(uint8_t)((((uint8_t)(b) * 0x80200802ULL) & 0x0884422110ULL) * 0x0101010101ULL >> 32)
return (bitrev8(code >> 8) | (uint16_t)bitrev8(code) << 8) >> (16 - len);
}