3
/*-------------------------------------------------------------*/
4
/*--- Huffman coding low-level stuff ---*/
6
/*-------------------------------------------------------------*/
9
This file is a part of bzip2 and/or libbzip2, a program and
10
library for lossless, block-sorting data compression.
12
Copyright (C) 1996-2002 Julian R Seward. All rights reserved.
14
Redistribution and use in source and binary forms, with or without
15
modification, are permitted provided that the following conditions
18
1. Redistributions of source code must retain the above copyright
19
notice, this list of conditions and the following disclaimer.
21
2. The origin of this software must not be misrepresented; you must
22
not claim that you wrote the original software. If you use this
23
software in a product, an acknowledgment in the product
24
documentation would be appreciated but is not required.
26
3. Altered source versions must be plainly marked as such, and must
27
not be misrepresented as being the original software.
29
4. The name of the author may not be used to endorse or promote
30
products derived from this software without specific prior written
33
THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
34
OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
35
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
36
ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
37
DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
38
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
39
GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
40
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
41
WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
42
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
43
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
45
Julian Seward, Cambridge, UK.
47
bzip2/libbzip2 version 1.0 of 21 March 2000
49
This program is based on (at least) the work of:
59
For more information on these sources, see the manual.
63
#include "bzlib_private.h"
65
/*---------------------------------------------------*/
66
#define WEIGHTOF(zz0) ((zz0) & 0xffffff00)
67
#define DEPTHOF(zz1) ((zz1) & 0x000000ff)
68
#define MYMAX(zz2,zz3) ((zz2) > (zz3) ? (zz2) : (zz3))
70
#define ADDWEIGHTS(zw1,zw2) \
71
(WEIGHTOF(zw1)+WEIGHTOF(zw2)) | \
72
(1 + MYMAX(DEPTHOF(zw1),DEPTHOF(zw2)))
77
zz = z; tmp = heap[zz]; \
78
while (weight[tmp] < weight[heap[zz >> 1]]) { \
79
heap[zz] = heap[zz >> 1]; \
88
zz = z; tmp = heap[zz]; \
91
if (yy > nHeap) break; \
93
weight[heap[yy+1]] < weight[heap[yy]]) \
95
if (weight[tmp] < weight[heap[yy]]) break; \
96
heap[zz] = heap[yy]; \
103
/*---------------------------------------------------*/
104
void BZ2_hbMakeCodeLengths ( UChar *len,
110
Nodes and heap entries run from 1. Entry 0
111
for both the heap and nodes is a sentinel.
113
Int32 nNodes, nHeap, n1, n2, i, j, k;
116
Int32 heap [ BZ_MAX_ALPHA_SIZE + 2 ];
117
Int32 weight [ BZ_MAX_ALPHA_SIZE * 2 ];
118
Int32 parent [ BZ_MAX_ALPHA_SIZE * 2 ];
120
for (i = 0; i < alphaSize; i++)
121
weight[i+1] = (freq[i] == 0 ? 1 : freq[i]) << 8;
132
for (i = 1; i <= alphaSize; i++) {
139
AssertH( nHeap < (BZ_MAX_ALPHA_SIZE+2), 2001 );
142
n1 = heap[1]; heap[1] = heap[nHeap]; nHeap--; DOWNHEAP(1);
143
n2 = heap[1]; heap[1] = heap[nHeap]; nHeap--; DOWNHEAP(1);
145
parent[n1] = parent[n2] = nNodes;
146
weight[nNodes] = ADDWEIGHTS(weight[n1], weight[n2]);
149
heap[nHeap] = nNodes;
153
AssertH( nNodes < (BZ_MAX_ALPHA_SIZE * 2), 2002 );
156
for (i = 1; i <= alphaSize; i++) {
159
while (parent[k] >= 0) { k = parent[k]; j++; }
161
if (j > maxLen) tooLong = True;
164
if (! tooLong) break;
166
for (i = 1; i < alphaSize; i++) {
175
/*---------------------------------------------------*/
176
void BZ2_hbAssignCodes ( Int32 *code,
185
for (n = minLen; n <= maxLen; n++) {
186
for (i = 0; i < alphaSize; i++)
187
if (length[i] == n) { code[i] = vec; vec++; };
193
/*---------------------------------------------------*/
194
void BZ2_hbCreateDecodeTables ( Int32 *limit,
205
for (i = minLen; i <= maxLen; i++)
206
for (j = 0; j < alphaSize; j++)
207
if (length[j] == i) { perm[pp] = j; pp++; };
209
for (i = 0; i < BZ_MAX_CODE_LEN; i++) base[i] = 0;
210
for (i = 0; i < alphaSize; i++) base[length[i]+1]++;
212
for (i = 1; i < BZ_MAX_CODE_LEN; i++) base[i] += base[i-1];
214
for (i = 0; i < BZ_MAX_CODE_LEN; i++) limit[i] = 0;
217
for (i = minLen; i <= maxLen; i++) {
218
vec += (base[i+1] - base[i]);
222
for (i = minLen + 1; i <= maxLen; i++)
223
base[i] = ((limit[i-1] + 1) << 1) - base[i];
227
/*-------------------------------------------------------------*/
228
/*--- end huffman.c ---*/
229
/*-------------------------------------------------------------*/