/* trees.c -- output deflated data using Huffman coding
- * Copyright (C) 1995-2010 Jean-loup Gailly
+ * 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
*/
* probability, to avoid transmitting the lengths for unused bit length codes.
*/
-#define Buf_size (8 * 2*sizeof(char))
-/* Number of bits used within bi_buf. (bi_buf might be implemented on
- * more than 16 bits on some systems.)
- */
-
/* ===========================================================================
* Local data. These are initialized only once.
*/
#ifdef DEBUG
local void send_bits OF((deflate_state *s, int value, int length));
-local void send_bits(
- deflate_state *s,
- int value,
- int length)
+local void send_bits(s, value, length)
+ deflate_state *s;
+ int value; /* value to send */
+ int length; /* number of bits */
{
Tracevv((stderr," l %2d v %4x ", length, value));
Assert(length > 0 && length <= 15, "invalid length");
/* ===========================================================================
* Initialize the tree data structures for a new zlib stream.
*/
-void ZLIB_INTERNAL _tr_init(
- deflate_state *s)
+void ZLIB_INTERNAL _tr_init(s)
+ deflate_state *s;
{
tr_static_init();
s->bi_buf = 0;
s->bi_valid = 0;
- s->last_eob_len = 8; /* enough lookahead for inflate */
#ifdef DEBUG
s->compressed_len = 0L;
s->bits_sent = 0L;
/* ===========================================================================
* Initialize a new block.
*/
-local void init_block(
- deflate_state *s)
+local void init_block(s)
+ deflate_state *s;
{
int n; /* iterates over tree elements */
* when the heap property is re-established (each father smaller than its
* two sons).
*/
-local void pqdownheap(
- deflate_state *s,
- ct_data *tree,
- int k)
+local void pqdownheap(s, tree, k)
+ deflate_state *s;
+ ct_data *tree; /* the tree to restore */
+ int k; /* node to move down */
{
int v = s->heap[k];
int j = k << 1; /* left son of k */
* The length opt_len is updated; static_len is also updated if stree is
* not null.
*/
-local void gen_bitlen(
- deflate_state *s,
- tree_desc *desc)
+local void gen_bitlen(s, desc)
+ deflate_state *s;
+ tree_desc *desc; /* the tree descriptor */
{
ct_data *tree = desc->dyn_tree;
int max_code = desc->max_code;
* OUT assertion: the field code is set for all tree elements of non
* zero code length.
*/
-local void gen_codes (
- ct_data *tree,
- int max_code,
- ushf *bl_count)
+local void gen_codes (tree, max_code, bl_count)
+ ct_data *tree; /* the tree to decorate */
+ int max_code; /* largest code with non zero frequency */
+ ushf *bl_count; /* number of codes at each bit length */
{
ush next_code[MAX_BITS+1]; /* next code value for each bit length */
ush code = 0; /* running code value */
* 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.
*/
-local void build_tree(
- deflate_state *s,
- tree_desc *desc)
+local void build_tree(s, desc)
+ deflate_state *s;
+ tree_desc *desc; /* the tree descriptor */
{
ct_data *tree = desc->dyn_tree;
const ct_data *stree = desc->stat_desc->static_tree;
* Scan a literal or distance tree to determine the frequencies of the codes
* in the bit length tree.
*/
-local void scan_tree (
- deflate_state *s,
- ct_data *tree,
- int max_code)
+local void scan_tree (s, tree, max_code)
+ deflate_state *s;
+ ct_data *tree; /* the tree to be scanned */
+ int max_code; /* and its largest code of non zero frequency */
{
int n; /* iterates over all tree elements */
int prevlen = -1; /* last emitted length */
* Send a literal or distance tree in compressed form, using the codes in
* bl_tree.
*/
-local void send_tree (
- deflate_state *s,
- ct_data *tree,
- int max_code)
+local void send_tree (s, tree, max_code)
+ deflate_state *s;
+ ct_data *tree; /* the tree to be scanned */
+ int max_code; /* and its largest code of non zero frequency */
{
int n; /* iterates over all tree elements */
int prevlen = -1; /* last emitted length */
* Construct the Huffman tree for the bit lengths and return the index in
* bl_order of the last bit length code to send.
*/
-local int build_bl_tree(
- deflate_state *s)
+local int build_bl_tree(s)
+ deflate_state *s;
{
int max_blindex; /* index of last bit length code of non zero freq */
* lengths of the bit length codes, the literal tree and the distance tree.
* IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
*/
-local void send_all_trees(
- deflate_state *s,
- int lcodes,
- int dcodes,
- int blcodes)
+local void send_all_trees(s, lcodes, dcodes, blcodes)
+ deflate_state *s;
+ int lcodes, dcodes, blcodes; /* number of codes for each tree */
{
int rank; /* index in bl_order */
/* ===========================================================================
* Send a stored block
*/
-void ZLIB_INTERNAL _tr_stored_block(
- deflate_state *s,
- charf *buf,
- ulg stored_len,
- int last)
+void ZLIB_INTERNAL _tr_stored_block(s, buf, stored_len, last)
+ deflate_state *s;
+ charf *buf; /* input block */
+ ulg stored_len; /* length of input block */
+ int last; /* one if this is the last block for a file */
{
send_bits(s, (STORED_BLOCK<<1)+last, 3); /* send block type */
#ifdef DEBUG
}
/* ===========================================================================
+ * Flush the bits in the bit buffer to pending output (leaves at most 7 bits)
+ */
+void ZLIB_INTERNAL _tr_flush_bits(s)
+ 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.
- * The current inflate code requires 9 bits of lookahead. If the
- * last two codes for the previous block (real code plus EOB) were coded
- * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode
- * the last real code. In this case we send two empty static blocks instead
- * of one. (There are no problems if the previous block is stored or fixed.)
- * To simplify the code, we assume the worst case of last real code encoded
- * on one bit only.
*/
-void ZLIB_INTERNAL _tr_align(
- deflate_state *s)
+void ZLIB_INTERNAL _tr_align(s)
+ deflate_state *s;
{
send_bits(s, STATIC_TREES<<1, 3);
send_code(s, END_BLOCK, static_ltree);
s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
#endif
bi_flush(s);
- /* Of the 10 bits for the empty block, we have already sent
- * (10 - bi_valid) bits. The lookahead for the last real code (before
- * the EOB of the previous block) was thus at least one plus the length
- * of the EOB plus what we have just sent of the empty static block.
- */
- if (1 + s->last_eob_len + 10 - s->bi_valid < 9) {
- send_bits(s, STATIC_TREES<<1, 3);
- send_code(s, END_BLOCK, static_ltree);
-#ifdef DEBUG
- s->compressed_len += 10L;
-#endif
- bi_flush(s);
- }
- s->last_eob_len = 7;
}
/* ===========================================================================
* Determine the best encoding for the current block: dynamic trees, static
* trees or store, and output the encoded block to the zip file.
*/
-void ZLIB_INTERNAL _tr_flush_block(
- deflate_state *s,
- charf *buf,
- ulg stored_len,
- int last)
+void ZLIB_INTERNAL _tr_flush_block(s, buf, stored_len, last)
+ deflate_state *s;
+ charf *buf; /* input block, or NULL if too old */
+ ulg stored_len; /* length of input block */
+ int last; /* one if this is the last block for a file */
{
ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
int max_blindex = 0; /* index of last bit length code of non zero freq */
* 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)
+int ZLIB_INTERNAL _tr_tally (s, dist, lc)
+ deflate_state *s;
+ unsigned dist; /* distance of matched string */
+ unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */
{
s->d_buf[s->last_lit] = (ush)dist;
s->l_buf[s->last_lit++] = (uch)lc;
/* ===========================================================================
* Send the block data compressed using the given Huffman trees
*/
-local void compress_block(
- deflate_state *s,
- ct_data *ltree,
- ct_data *dtree)
+local void compress_block(s, ltree, dtree)
+ deflate_state *s;
+ ct_data *ltree; /* literal tree */
+ ct_data *dtree; /* distance tree */
{
unsigned dist; /* distance of matched string */
int lc; /* match length or unmatched char (if dist == 0) */
} while (lx < s->last_lit);
send_code(s, END_BLOCK, ltree);
- s->last_eob_len = ltree[END_BLOCK].Len;
}
/* ===========================================================================
* (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).
* IN assertion: the fields Freq of dyn_ltree are set.
*/
-local int detect_data_type(
- deflate_state *s)
+local int detect_data_type(s)
+ deflate_state *s;
{
/* black_mask is the bit mask of black-listed bytes
* set bits 0..6, 14..25, and 28..31
* method would use a table)
* IN assertion: 1 <= len <= 15
*/
-local unsigned bi_reverse(
- unsigned code,
- int len)
+local unsigned bi_reverse(code, len)
+ unsigned code; /* the value to invert */
+ int len; /* its bit length */
{
register unsigned res = 0;
do {
/* ===========================================================================
* Flush the bit buffer, keeping at most 7 bits in it.
*/
-local void bi_flush(
- deflate_state *s)
+local void bi_flush(s)
+ deflate_state *s;
{
if (s->bi_valid == 16) {
put_short(s, s->bi_buf);
/* ===========================================================================
* Flush the bit buffer and align the output on a byte boundary
*/
-local void bi_windup(
- deflate_state *s)
+local void bi_windup(s)
+ deflate_state *s;
{
if (s->bi_valid > 8) {
put_short(s, s->bi_buf);
* Copy a stored block, storing first the length and its
* one's complement if requested.
*/
-local void copy_block(
- deflate_state *s,
- charf *buf,
- unsigned len,
- int header)
+local void copy_block(s, buf, len, header)
+ deflate_state *s;
+ charf *buf; /* the input data */
+ unsigned len; /* its length */
+ int header; /* true if block header must be written */
{
bi_windup(s); /* align on byte boundary */
- s->last_eob_len = 8; /* enough lookahead for inflate */
if (header) {
put_short(s, (ush)len);
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