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 /*-------------------------------------------------------------*/