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/* trees.c -- output deflated data using Huffman coding
* Copyright (C) 1995-2012 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.
*/
/* @(#) $Id$ */
#include "deflate.h"
/* ===========================================================================
* Constants
*/
#define MAX_BL_BITS 7
/* Bit length codes must not exceed MAX_BL_BITS bits */
#define END_BLOCK 256
/* end of block literal code */
#define REP_3_6 16
/* repeat previous bit length 3-6 times (2 bits of repeat count) */
#define REPZ_3_10 17
/* repeat a zero length 3-10 times (3 bits of repeat count) */
#define REPZ_11_138 18
/* repeat a zero length 11-138 times (7 bits of repeat count) */
static const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
= {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};
static const int extra_dbits[D_CODES] /* extra bits for each distance code */
= {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};
static const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
= {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
static const uch bl_order[BL_CODES]
= {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
/* 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.
*/
#define DIST_CODE_LEN 512 /* see definition of array dist_code below */
#include "trees.h"
struct static_tree_desc_s {
const ct_data *static_tree; /* static tree or NULL */
const intf *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 */
int max_length; /* max bit length for the codes */
};
static static_tree_desc static_l_desc =
{static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
static static_tree_desc static_d_desc =
{static_dtree, extra_dbits, 0, D_CODES, MAX_BITS};
static 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 compress_block (deflate_state *s, const ct_data *ltree,
const ct_data *dtree);
static int detect_data_type (deflate_state *s);
static unsigned bi_reverse (unsigned value, int length);
static void bi_windup (deflate_state *s);
static void bi_flush (deflate_state *s);
# define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
/* Send a code of the given tree. c and tree must not have side effects */
/* ===========================================================================
* Output a short LSB first on the stream.
* IN assertion: there is enough room in pendingBuf.
*/
#define put_short(s, w) { \
put_byte(s, (uch)((w) & 0xff)); \
put_byte(s, (uch)((ush)(w) >> 8)); \
}
/* ===========================================================================
* Send a value on a given number of bits.
* IN assertion: length <= 16 and value fits in length bits.
*/
#define send_bits(s, value, length) \
{ int len = length;\
if (s->bi_valid > (int)Buf_size - len) {\
int val = value;\
s->bi_buf |= (ush)val << s->bi_valid;\
put_short(s, s->bi_buf);\
s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
s->bi_valid += len - Buf_size;\
} else {\
s->bi_buf |= (ush)(value) << s->bi_valid;\
s->bi_valid += len;\
}\
}
/* ===========================================================================
* 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->last_lit = s->matches = 0;
}
/* the arguments must not have side effects */
/* ===========================================================================
* Initialize the tree data structures for a new zlib stream.
*/
void ZLIB_INTERNAL _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;
/* Initialize the first block of the first file: */
init_block(s);
}
#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)
{
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)
{
ct_data *tree = desc->dyn_tree;
int max_code = desc->max_code;
const ct_data *stree = desc->stat_desc->static_tree;
const intf *extra = desc->stat_desc->extra_bits;
int base = desc->stat_desc->extra_base;
int max_length = desc->stat_desc->max_length;
int h; /* heap index */
int n, m; /* iterate over the tree elements */
int bits; /* bit length */
int xbits; /* extra bits */
ush 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 + 1;
if (bits > max_length)
{
bits = max_length;
overflow++;
}
tree[n].Len = (ush)bits;
/* We overwrite tree[n].Dad which is no longer needed */
if (n > max_code) continue; /* not a leaf node */
s->bl_count[bits]++;
xbits = 0;
if (n >= base) xbits = extra[n-base];
f = tree[n].Freq;
s->opt_len += (ulg)f * (bits + xbits);
if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
}
if (overflow == 0) return;
Trace((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] += 2; /* 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 ((unsigned) tree[m].Len != (unsigned) bits) {
Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
s->opt_len += ((long)bits - (long)tree[m].Len)
*(long)tree[m].Freq;
tree[m].Len = (ush)bits;
}
n--;
}
}
}
/* ===========================================================================
* Generate the codes for a given tree and bit counts (which need not be
* optimal).
* IN assertion: the array bl_count contains the bit length statistics for
* the given tree and the field len is set for all tree elements.
* OUT assertion: the field code is set for all tree elements of non
* zero code length.
*/
static void gen_codes (ct_data *tree, int max_code, ushf *bl_count)
{
ush next_code[MAX_BITS+1]; /* next code value for each bit length */
ush codes = 0; /* running code value */
int bits; /* bit index */
int n; /* code index */
/* The distribution counts are first used to generate the code values
* without bit reversal.
*/
for (bits = 1; bits <= MAX_BITS; bits++) {
next_code[bits] = codes = (codes + bl_count[bits-1]) << 1;
}
/* Check that the bit counts in bl_count are consistent. The last code
* must be all ones.
*/
Assert (codes + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
"inconsistent bit counts");
for (n = 0; n <= max_code; n++) {
int len = tree[n].Len;
if (len == 0) continue;
/* Now reverse the bits */
tree[n].Code = bi_reverse(next_code[len]++, len);
Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
}
}
/* ===========================================================================
* Construct one Huffman tree and assigns the code bit strings and lengths.
* Update the total bit length for the current block.
* IN assertion: the field freq is set for all tree elements.
* OUT assertions: the fields len and code are set to the optimal bit length
* and corresponding code. The length opt_len is updated; static_len is
* also updated if stree is not null. The field max_code is set.
*/
static void build_tree(deflate_state *s, tree_desc *desc)
{
ct_data *tree = desc->dyn_tree;
const ct_data *stree = desc->stat_desc->static_tree;
int elems = desc->stat_desc->elems;
int n, m; /* iterate over heap elements */
int max_code = -1; /* largest code with non zero frequency */
int node; /* new node being created */
/* Construct the initial heap, with least frequent element in
* heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
* heap[0] is not used.
*/
s->heap_len = 0;
s->heap_max = HEAP_SIZE;
for (n = 0; n < elems; n++) {
if (tree[n].Freq != 0) {
s->heap[++(s->heap_len)] = max_code = n;
s->depth[n] = 0;
} else {
tree[n].Len = 0;
}
}
/* The pkzip format requires that at least one distance code exists,
* and that at least one bit should be sent even if there is only one
* possible code. So to avoid special checks later on we force at least
* two codes of non zero frequency.
*/
while (s->heap_len < 2) {
node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
tree[node].Freq = 1;
s->depth[node] = 0;
s->opt_len--; if (stree) s->static_len -= stree[node].Len;
/* node is 0 or 1 so it does not have extra bits */
}
desc->max_code = max_code;
/* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
* establish sub-heaps of increasing lengths:
*/
for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
/* Construct the Huffman tree by repeatedly combining the least two
* frequent nodes.
*/
node = elems; /* next internal node of the tree */
do {
pqremove(s, tree, n); /* n = node of least frequency */
m = s->heap[SMALLEST]; /* m = node of next least frequency */
s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
s->heap[--(s->heap_max)] = m;
/* Create a new node father of n and m */
tree[node].Freq = tree[n].Freq + tree[m].Freq;
s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
s->depth[n] : s->depth[m]) + 1);
tree[n].Dad = tree[m].Dad = (ush)node;
#ifdef DUMP_BL_TREE
if (tree == s->bl_tree) {
fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
}
#endif
/* and insert the new node in the heap */
s->heap[SMALLEST] = node++;
pqdownheap(s, tree, SMALLEST);
} while (s->heap_len >= 2);
s->heap[--(s->heap_max)] = s->heap[SMALLEST];
/* At this point, the fields freq and dad are set. We can now
* generate the bit lengths.
*/
gen_bitlen(s, (tree_desc *)desc);
/* The field len is now set, we can generate the bit codes */
gen_codes ((ct_data *)tree, max_code, s->bl_count);
}
/* ===========================================================================
* Scan a literal or distance tree to determine the frequencies of the codes
* in the bit length tree.
*/
static void scan_tree (deflate_state *s, ct_data *tree, 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 = (ush)0xffff; /* guard */
for (n = 0; n <= max_code; n++) {
curlen = nextlen; nextlen = tree[n+1].Len;
if (++count < max_count && curlen == nextlen) {
continue;
} else if (count < min_count) {
s->bl_tree[curlen].Freq += count;
} else if (curlen != 0) {
if (curlen != prevlen) s->bl_tree[curlen].Freq++;
s->bl_tree[REP_3_6].Freq++;
} else if (count <= 10) {
s->bl_tree[REPZ_3_10].Freq++;
} else {
s->bl_tree[REPZ_11_138].Freq++;
}
count = 0; prevlen = curlen;
if (nextlen == 0) {
max_count = 138;
min_count = 3;
} else if (curlen == nextlen) {
max_count = 6;
min_count = 3;
} else {
max_count = 7;
min_count = 4;
}
}
}
/* ===========================================================================
* Send a literal or distance tree in compressed form, using the codes in
* bl_tree.
*/
static void send_tree (deflate_state *s, ct_data *tree, 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(s, curlen, s->bl_tree); } while (--count != 0);
} else if (curlen != 0) {
if (curlen != prevlen) {
send_code(s, curlen, s->bl_tree); count--;
}
Assert(count >= 3 && count <= 6, " 3_6?");
send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
} else if (count <= 10) {
send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
} else {
send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
}
count = 0; prevlen = curlen;
if (nextlen == 0) {
max_count = 138;
min_count = 3;
} else if (curlen == nextlen) {
max_count = 6;
min_count = 3;
} else {
max_count = 7;
min_count = 4;
}
}
}
/* ===========================================================================
* Construct the Huffman tree for the bit lengths and return the index in
* bl_order of the last bit length code to send.
*/
static int build_bl_tree(deflate_state *s)
{
int max_blindex; /* index of last bit length code of non zero freq */
/* Determine the bit length frequencies for literal and distance trees */
scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
/* Build the bit length tree: */
build_tree(s, (tree_desc *)(&(s->bl_desc)));
/* opt_len now includes the length of the tree representations, except
* the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
*/
/* Determine the number of bit length codes to send. The pkzip format
* requires that at least 4 bit length codes be sent. (appnote.txt says
* 3 but the actual value used is 4.)
*/
for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
}
/* Update opt_len to include the bit length tree and counts */
s->opt_len += 3*(max_blindex+1) + 5+5+4;
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");
send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
send_bits(s, dcodes-1, 5);
send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */
for (rank = 0; rank < blcodes; rank++) {
send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
}
send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
}
/* ===========================================================================
* Send a stored block
*/
void ZLIB_INTERNAL _tr_stored_block(deflate_state *s, charf *buf, ulg stored_len, int last)
{
send_bits(s, (STORED_BLOCK<<1)+last, 3); /* send block type */
bi_windup(s); /* align on byte boundary */
put_short(s, (ush)stored_len);
put_short(s, (ush)~stored_len);
memcpy(s->pending_buf + s->pending, buf, stored_len);
s->pending += stored_len;
}
/* ===========================================================================
* Flush the bits in the bit buffer to pending output (leaves at most 7 bits)
*/
void ZLIB_INTERNAL _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 ZLIB_INTERNAL _tr_align(deflate_state *s)
{
send_bits(s, STATIC_TREES<<1, 3);
send_code(s, END_BLOCK, static_ltree);
bi_flush(s);
}
/* ===========================================================================
* Determine the best encoding for the current block: dynamic trees, static
* trees or store, and output the encoded block to the zip file.
*/
void ZLIB_INTERNAL _tr_flush_block(deflate_state *s, charf *buf, ulg stored_len, int last)
{
ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
int max_blindex = 0; /* index of last bit length code of non zero freq */
/* Build the Huffman trees unless a stored block is forced */
if (s->level > 0) {
/* Check if the file is 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)));
build_tree(s, (tree_desc *)(&(s->d_desc)));
/* 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;
if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
} else {
Assert(buf != (char*)0, "lost buf");
opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
}
#ifdef FORCE_STORED
if (buf != (char*)0) { /* force stored block */
#else
if (stored_len+4 <= opt_lenb && buf != (char*)0) {
/* 4: two words for the lengths */
#endif
/* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
* Otherwise we can't have processed more than WSIZE input bytes since
* the last block flush, because compression would have been
* successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
* transform a block into a stored block.
*/
_tr_stored_block(s, buf, stored_len, last);
#ifdef FORCE_STATIC
} else if (static_lenb >= 0) { /* force static trees */
#else
} else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
#endif
send_bits(s, (STATIC_TREES<<1)+last, 3);
compress_block(s, (const ct_data *)static_ltree,
(const ct_data *)static_dtree);
} else {
send_bits(s, (DYN_TREES<<1)+last, 3);
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);
}
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 uLong implemented on 32 bits.
*/
init_block(s);
if (last) {
bi_windup(s);
}
}
/* ===========================================================================
* Save the match info and tally the frequency counts. Return true if
* the current block must be flushed.
*/
int ZLIB_INTERNAL _tr_tally (deflate_state *s, unsigned dist, unsigned lc)
{
s->d_buf[s->last_lit] = (ush)dist;
s->l_buf[s->last_lit++] = (uch)lc;
if (dist == 0) {
/* lc is the unmatched char */
s->dyn_ltree[lc].Freq++;
} else {
s->matches++;
/* Here, lc is the match length - MIN_MATCH */
dist--; /* dist = match distance - 1 */
Assert((ush)dist < (ush)MAX_DIST(s) &&
(ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
(ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match");
s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
s->dyn_dtree[d_code(dist)].Freq++;
}
#ifdef TRUNCATE_BLOCK
/* Try to guess if it is profitable to stop the current block here */
if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
/* Compute an upper bound for the compressed length */
ulg out_length = (ulg)s->last_lit*8L;
ulg in_length = (ulg)((long)s->strstart - s->block_start);
int dcode;
for (dcode = 0; dcode < D_CODES; dcode++) {
out_length += (ulg)s->dyn_dtree[dcode].Freq *
(5L+extra_dbits[dcode]);
}
out_length >>= 3;
if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
}
#endif
return (s->last_lit == s->lit_bufsize-1);
/* We avoid equality with lit_bufsize because of wraparound at 64K
* on 16 bit machines and because stored blocks are restricted to
* 64K-1 bytes.
*/
}
/* ===========================================================================
* Send the block data compressed using the given Huffman trees
*/
static void compress_block(deflate_state *s, const ct_data *ltree, const 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 codes; /* the code to send */
int extra; /* number of extra bits to send */
if (s->last_lit != 0) do {
dist = s->d_buf[lx];
lc = s->l_buf[lx++];
if (dist == 0) {
send_code(s, lc, ltree); /* send a literal byte */
Tracecv(isgraph(lc), (stderr," '%c' ", lc));
} else {
/* Here, lc is the match length - MIN_MATCH */
codes = _length_code[lc];
send_code(s, codes + LITERALS+1, ltree); /* send the length code */
extra = extra_lbits[codes];
if (extra != 0) {
lc -= base_length[codes];
send_bits(s, lc, extra); /* send the extra length bits */
}
dist--; /* dist is now the match distance - 1 */
codes = d_code(dist);
Assert (codes < D_CODES, "bad d_code");
send_code(s, codes, dtree); /* send the distance code */
extra = extra_dbits[codes];
if (extra != 0) {
dist -= base_dist[codes];
send_bits(s, dist, extra); /* send the extra distance bits */
}
} /* literal or match pair ? */
/* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
"pendingBuf overflow");
} while (lx < s->last_lit);
send_code(s, END_BLOCK, ltree);
}
/* ===========================================================================
* 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;
}
/* ===========================================================================
* Reverse the first len bits of a code, using straightforward code (a faster
* method would use a table)
* IN assertion: 1 <= len <= 15
*/
static unsigned bi_reverse(unsigned codes, int len)
{
register unsigned res = 0;
do {
res |= codes & 1;
codes >>= 1;
res <<= 1;
} while (--len > 0);
return res >> 1;
}
/* ===========================================================================
* Flush the bit buffer, keeping at most 7 bits in it.
*/
static void bi_flush(deflate_state *s)
{
if (s->bi_valid == 16) {
put_short(s, s->bi_buf);
s->bi_buf = 0;
s->bi_valid = 0;
} else if (s->bi_valid >= 8) {
put_byte(s, (Byte)s->bi_buf);
s->bi_buf >>= 8;
s->bi_valid -= 8;
}
}
/* ===========================================================================
* Flush the bit buffer and align the output on a byte boundary
*/
static void bi_windup(deflate_state *s)
{
if (s->bi_valid > 8) {
put_short(s, s->bi_buf);
} else if (s->bi_valid > 0) {
put_byte(s, (Byte)s->bi_buf);
}
s->bi_buf = 0;
s->bi_valid = 0;
}
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