/* -*-mode:java; c-basic-offset:2; -*- */
/*
Copyright (c) 2000,2001,2002,2003 ymnk, JCraft,Inc. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
1. Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in
the documentation and/or other materials provided with the distribution.
3. The names of the authors may not be used to endorse or promote products
derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JCRAFT,
INC. OR ANY CONTRIBUTORS TO THIS SOFTWARE BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* This program is based on zlib-1.1.3, so all credit should go authors
* Jean-loup Gailly(jloup@gzip.org) and Mark Adler(madler@alumni.caltech.edu)
* and contributors of zlib.
*/
package com.jcraft.jzlib;
final class
Tree{
static final private int
MAX_BITS=15;
static final private int
BL_CODES=19;
static final private int
D_CODES=30;
static final private int
LITERALS=256;
static final private int
LENGTH_CODES=29;
static final private int
L_CODES=(
LITERALS+1+
LENGTH_CODES);
static final private int
HEAP_SIZE=(2*
L_CODES+1);
// Bit length codes must not exceed MAX_BL_BITS bits
static final int
MAX_BL_BITS=7;
// end of block literal code
static final int
END_BLOCK=256;
// repeat previous bit length 3-6 times (2 bits of repeat count)
static final int
REP_3_6=16;
// repeat a zero length 3-10 times (3 bits of repeat count)
static final int
REPZ_3_10=17;
// repeat a zero length 11-138 times (7 bits of repeat count)
static final int
REPZ_11_138=18;
// extra bits for each length code
static final int[]
extra_lbits={
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
};
// extra bits for each distance code
static final int[]
extra_dbits={
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
};
// extra bits for each bit length code
static final int[]
extra_blbits={
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7
};
static final byte[]
bl_order={
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.
static final int
Buf_size=8*2;
// see definition of array dist_code below
static final int
DIST_CODE_LEN=512;
static final byte[]
_dist_code = {
0, 1, 2, 3, 4, 4, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8,
8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9, 10, 10, 10, 10, 10, 10, 10, 10,
10, 10, 10, 10, 10, 10, 10, 10, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
11, 11, 11, 11, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12,
12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 13, 13, 13, 13,
13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13,
13, 13, 13, 13, 13, 13, 13, 13, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 15, 15, 15, 15, 15, 15, 15, 15,
15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 0, 0, 16, 17,
18, 18, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 22, 22, 22, 22, 22, 22, 22, 22,
23, 23, 23, 23, 23, 23, 23, 23, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
24, 24, 24, 24, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 27, 27, 27, 27, 27, 27, 27, 27,
27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
27, 27, 27, 27, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28,
28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28,
28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28,
28, 28, 28, 28, 28, 28, 28, 28, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29,
29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29,
29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29,
29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29
};
static final byte[]
_length_code={
0, 1, 2, 3, 4, 5, 6, 7, 8, 8, 9, 9, 10, 10, 11, 11, 12, 12, 12, 12,
13, 13, 13, 13, 14, 14, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 16, 16, 16, 16,
17, 17, 17, 17, 17, 17, 17, 17, 18, 18, 18, 18, 18, 18, 18, 18, 19, 19, 19, 19,
19, 19, 19, 19, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20,
21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 22, 22, 22, 22,
22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 23, 23, 23, 23, 23, 23, 23, 23,
23, 23, 23, 23, 23, 23, 23, 23, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 26, 26, 26, 26, 26, 26, 26, 26,
26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
26, 26, 26, 26, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 28
};
static final int[]
base_length = {
0, 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 16, 20, 24, 28, 32, 40, 48, 56,
64, 80, 96, 112, 128, 160, 192, 224, 0
};
static final int[]
base_dist = {
0, 1, 2, 3, 4, 6, 8, 12, 16, 24,
32, 48, 64, 96, 128, 192, 256, 384, 512, 768,
1024, 1536, 2048, 3072, 4096, 6144, 8192, 12288, 16384, 24576
};
// Mapping from a distance to a distance code. dist is the distance - 1 and
// must not have side effects. _dist_code[256] and _dist_code[257] are never
// used.
static int
d_code(int
dist){
return ((
dist) < 256 ?
_dist_code[
dist] :
_dist_code[256+((
dist)>>>7)]);
}
short[]
dyn_tree; // the dynamic tree
int
max_code; // largest code with non zero frequency
StaticTree stat_desc; // the corresponding static tree
// 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.
void
gen_bitlen(
Deflate s){
short[]
tree =
dyn_tree;
short[]
stree =
stat_desc.
static_tree;
int[]
extra =
stat_desc.
extra_bits;
int
base =
stat_desc.
extra_base;
int
max_length =
stat_desc.
max_length;
int
h; // heap index
int
n,
m; // iterate over the tree elements
int
bits; // bit length
int
xbits; // extra bits
short
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]*2+1] = 0; // root of the heap
for(
h=
s.
heap_max+1;
h<
HEAP_SIZE;
h++){
n =
s.
heap[
h];
bits =
tree[
tree[
n*2+1]*2+1] + 1;
if (
bits >
max_length){
bits =
max_length;
overflow++; }
tree[
n*2+1] = (short)
bits;
// We overwrite tree[n*2+1] 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*2];
s.
opt_len +=
f * (
bits +
xbits);
if (
stree!=null)
s.
static_len +=
f * (
stree[
n*2+1] +
xbits);
}
if (
overflow == 0) return;
// 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);
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*2+1] !=
bits) {
s.
opt_len += ((long)
bits - (long)
tree[
m*2+1])*(long)
tree[
m*2];
tree[
m*2+1] = (short)
bits;
}
n--;
}
}
}
// 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.
void
build_tree(
Deflate s){
short[]
tree=
dyn_tree;
short[]
stree=
stat_desc.
static_tree;
int
elems=
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[1]. 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*2] != 0) {
s.
heap[++
s.
heap_len] =
max_code =
n;
s.
depth[
n] = 0;
}
else{
tree[
n*2+1] = 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*2] = 1;
s.
depth[
node] = 0;
s.
opt_len--; if (
stree!=null)
s.
static_len -=
stree[
node*2+1];
// node is 0 or 1 so it does not have extra bits
}
this.
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--)
s.
pqdownheap(
tree,
n);
// Construct the Huffman tree by repeatedly combining the least two
// frequent nodes.
node=
elems; // next internal node of the tree
do{
// n = node of least frequency
n=
s.
heap[1];
s.
heap[1]=
s.
heap[
s.
heap_len--];
s.
pqdownheap(
tree, 1);
m=
s.
heap[1]; // 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*2] = (short)(
tree[
n*2] +
tree[
m*2]);
s.
depth[
node] = (byte)(
Math.
max(
s.
depth[
n],
s.
depth[
m])+1);
tree[
n*2+1] =
tree[
m*2+1] = (short)
node;
// and insert the new node in the heap
s.
heap[1] =
node++;
s.
pqdownheap(
tree, 1);
}
while(
s.
heap_len>=2);
s.
heap[--
s.
heap_max] =
s.
heap[1];
// At this point, the fields freq and dad are set. We can now
// generate the bit lengths.
gen_bitlen(
s);
// The field len is now set, we can generate the bit codes
gen_codes(
tree,
max_code,
s.
bl_count,
s.
next_code);
}
// 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.
private final static void
gen_codes(
short[]
tree, // the tree to decorate
int
max_code, // largest code with non zero frequency
short[]
bl_count, // number of codes at each bit length
short[]
next_code){
short
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.
next_code[0]=0;
for (
bits = 1;
bits <=
MAX_BITS;
bits++) {
next_code[
bits] =
code = (short)((
code +
bl_count[
bits-1]) << 1);
}
// 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*2+1];
if (
len == 0) continue;
// Now reverse the bits
tree[
n*2] = (short)(
bi_reverse(
next_code[
len]++,
len));
}
}
// Reverse the first len bits of a code, using straightforward code (a faster
// method would use a table)
// IN assertion: 1 <= len <= 15
private final static int
bi_reverse(
int
code, // the value to invert
int
len // its bit length
){
int
res = 0;
do{
res|=
code&1;
code>>>=1;
res<<=1;
}
while(--
len>0);
return
res>>>1;
}
}