246 lines
8.4 KiB
C
246 lines
8.4 KiB
C
|
|
||
|
|
/*-------------------------------------------------------------*/
|
||
|
|
/*--- Huffman coding low-level stuff ---*/
|
||
|
|
/*--- huffman.c ---*/
|
||
|
|
/*-------------------------------------------------------------*/
|
||
|
|
|
||
|
|
/*--
|
||
|
|
This file is a part of bzip2 and/or libbzip2, a program and
|
||
|
|
library for lossless, block-sorting data compression.
|
||
|
|
|
||
|
|
Copyright (C) 1996-2005 Julian R Seward. 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. The origin of this software must not be misrepresented; you must
|
||
|
|
not claim that you wrote the original software. If you use this
|
||
|
|
software in a product, an acknowledgment in the product
|
||
|
|
documentation would be appreciated but is not required.
|
||
|
|
|
||
|
|
3. Altered source versions must be plainly marked as such, and must
|
||
|
|
not be misrepresented as being the original software.
|
||
|
|
|
||
|
|
4. The name of the author may not be used to endorse or promote
|
||
|
|
products derived from this software without specific prior written
|
||
|
|
permission.
|
||
|
|
|
||
|
|
THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
|
||
|
|
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 THE AUTHOR 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.
|
||
|
|
|
||
|
|
Julian Seward, Cambridge, UK.
|
||
|
|
jseward@bzip.org
|
||
|
|
bzip2/libbzip2 version 1.0 of 21 March 2000
|
||
|
|
|
||
|
|
This program is based on (at least) the work of:
|
||
|
|
Mike Burrows
|
||
|
|
David Wheeler
|
||
|
|
Peter Fenwick
|
||
|
|
Alistair Moffat
|
||
|
|
Radford Neal
|
||
|
|
Ian H. Witten
|
||
|
|
Robert Sedgewick
|
||
|
|
Jon L. Bentley
|
||
|
|
|
||
|
|
For more information on these sources, see the manual.
|
||
|
|
--*/
|
||
|
|
|
||
|
|
|
||
|
|
#include "bzlib_private.h"
|
||
|
|
|
||
|
|
/*---------------------------------------------------*/
|
||
|
|
#define WEIGHTOF(zz0) ((zz0) & 0xffffff00)
|
||
|
|
#define DEPTHOF(zz1) ((zz1) & 0x000000ff)
|
||
|
|
#define MYMAX(zz2,zz3) ((zz2) > (zz3) ? (zz2) : (zz3))
|
||
|
|
|
||
|
|
#define ADDWEIGHTS(zw1,zw2) \
|
||
|
|
(WEIGHTOF(zw1)+WEIGHTOF(zw2)) | \
|
||
|
|
(1 + MYMAX(DEPTHOF(zw1),DEPTHOF(zw2)))
|
||
|
|
|
||
|
|
#define UPHEAP(z) \
|
||
|
|
{ \
|
||
|
|
Int32 zz, tmp; \
|
||
|
|
zz = z; tmp = heap[zz]; \
|
||
|
|
while (weight[tmp] < weight[heap[zz >> 1]]) { \
|
||
|
|
heap[zz] = heap[zz >> 1]; \
|
||
|
|
zz >>= 1; \
|
||
|
|
} \
|
||
|
|
heap[zz] = tmp; \
|
||
|
|
}
|
||
|
|
|
||
|
|
#define DOWNHEAP(z) \
|
||
|
|
{ \
|
||
|
|
Int32 zz, yy, tmp; \
|
||
|
|
zz = z; tmp = heap[zz]; \
|
||
|
|
while (True) { \
|
||
|
|
yy = zz << 1; \
|
||
|
|
if (yy > nHeap) break; \
|
||
|
|
if (yy < nHeap && \
|
||
|
|
weight[heap[yy+1]] < weight[heap[yy]]) \
|
||
|
|
yy++; \
|
||
|
|
if (weight[tmp] < weight[heap[yy]]) break; \
|
||
|
|
heap[zz] = heap[yy]; \
|
||
|
|
zz = yy; \
|
||
|
|
} \
|
||
|
|
heap[zz] = tmp; \
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
/*---------------------------------------------------*/
|
||
|
|
void BZ2_hbMakeCodeLengths ( UChar *len,
|
||
|
|
Int32 *freq,
|
||
|
|
Int32 alphaSize,
|
||
|
|
Int32 maxLen )
|
||
|
|
{
|
||
|
|
/*--
|
||
|
|
Nodes and heap entries run from 1. Entry 0
|
||
|
|
for both the heap and nodes is a sentinel.
|
||
|
|
--*/
|
||
|
|
Int32 nNodes, nHeap, n1, n2, i, j, k;
|
||
|
|
Bool tooLong;
|
||
|
|
|
||
|
|
Int32 heap [ BZ_MAX_ALPHA_SIZE + 2 ];
|
||
|
|
Int32 weight [ BZ_MAX_ALPHA_SIZE * 2 ];
|
||
|
|
Int32 parent [ BZ_MAX_ALPHA_SIZE * 2 ];
|
||
|
|
|
||
|
|
for (i = 0; i < alphaSize; i++)
|
||
|
|
weight[i+1] = (freq[i] == 0 ? 1 : freq[i]) << 8;
|
||
|
|
|
||
|
|
while (True) {
|
||
|
|
|
||
|
|
nNodes = alphaSize;
|
||
|
|
nHeap = 0;
|
||
|
|
|
||
|
|
heap[0] = 0;
|
||
|
|
weight[0] = 0;
|
||
|
|
parent[0] = -2;
|
||
|
|
|
||
|
|
for (i = 1; i <= alphaSize; i++) {
|
||
|
|
parent[i] = -1;
|
||
|
|
nHeap++;
|
||
|
|
heap[nHeap] = i;
|
||
|
|
UPHEAP(nHeap);
|
||
|
|
}
|
||
|
|
|
||
|
|
AssertH( nHeap < (BZ_MAX_ALPHA_SIZE+2), 2001 );
|
||
|
|
|
||
|
|
while (nHeap > 1) {
|
||
|
|
n1 = heap[1]; heap[1] = heap[nHeap]; nHeap--; DOWNHEAP(1);
|
||
|
|
n2 = heap[1]; heap[1] = heap[nHeap]; nHeap--; DOWNHEAP(1);
|
||
|
|
nNodes++;
|
||
|
|
parent[n1] = parent[n2] = nNodes;
|
||
|
|
weight[nNodes] = ADDWEIGHTS(weight[n1], weight[n2]);
|
||
|
|
parent[nNodes] = -1;
|
||
|
|
nHeap++;
|
||
|
|
heap[nHeap] = nNodes;
|
||
|
|
UPHEAP(nHeap);
|
||
|
|
}
|
||
|
|
|
||
|
|
AssertH( nNodes < (BZ_MAX_ALPHA_SIZE * 2), 2002 );
|
||
|
|
|
||
|
|
tooLong = False;
|
||
|
|
for (i = 1; i <= alphaSize; i++) {
|
||
|
|
j = 0;
|
||
|
|
k = i;
|
||
|
|
while (parent[k] >= 0) { k = parent[k]; j++; }
|
||
|
|
len[i-1] = j;
|
||
|
|
if (j > maxLen) tooLong = True;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (! tooLong) break;
|
||
|
|
|
||
|
|
/* 17 Oct 04: keep-going condition for the following loop used
|
||
|
|
to be 'i < alphaSize', which missed the last element,
|
||
|
|
theoretically leading to the possibility of the compressor
|
||
|
|
looping. However, this count-scaling step is only needed if
|
||
|
|
one of the generated Huffman code words is longer than
|
||
|
|
maxLen, which up to and including version 1.0.2 was 20 bits,
|
||
|
|
which is extremely unlikely. In version 1.0.3 maxLen was
|
||
|
|
changed to 17 bits, which has minimal effect on compression
|
||
|
|
ratio, but does mean this scaling step is used from time to
|
||
|
|
time, enough to verify that it works.
|
||
|
|
|
||
|
|
This means that bzip2-1.0.3 and later will only produce
|
||
|
|
Huffman codes with a maximum length of 17 bits. However, in
|
||
|
|
order to preserve backwards compatibility with bitstreams
|
||
|
|
produced by versions pre-1.0.3, the decompressor must still
|
||
|
|
handle lengths of up to 20. */
|
||
|
|
|
||
|
|
for (i = 1; i <= alphaSize; i++) {
|
||
|
|
j = weight[i] >> 8;
|
||
|
|
j = 1 + (j / 2);
|
||
|
|
weight[i] = j << 8;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
/*---------------------------------------------------*/
|
||
|
|
void BZ2_hbAssignCodes ( Int32 *code,
|
||
|
|
UChar *length,
|
||
|
|
Int32 minLen,
|
||
|
|
Int32 maxLen,
|
||
|
|
Int32 alphaSize )
|
||
|
|
{
|
||
|
|
Int32 n, vec, i;
|
||
|
|
|
||
|
|
vec = 0;
|
||
|
|
for (n = minLen; n <= maxLen; n++) {
|
||
|
|
for (i = 0; i < alphaSize; i++)
|
||
|
|
if (length[i] == n) { code[i] = vec; vec++; };
|
||
|
|
vec <<= 1;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
/*---------------------------------------------------*/
|
||
|
|
void BZ2_hbCreateDecodeTables ( Int32 *limit,
|
||
|
|
Int32 *base,
|
||
|
|
Int32 *perm,
|
||
|
|
UChar *length,
|
||
|
|
Int32 minLen,
|
||
|
|
Int32 maxLen,
|
||
|
|
Int32 alphaSize )
|
||
|
|
{
|
||
|
|
Int32 pp, i, j, vec;
|
||
|
|
|
||
|
|
pp = 0;
|
||
|
|
for (i = minLen; i <= maxLen; i++)
|
||
|
|
for (j = 0; j < alphaSize; j++)
|
||
|
|
if (length[j] == i) { perm[pp] = j; pp++; };
|
||
|
|
|
||
|
|
for (i = 0; i < BZ_MAX_CODE_LEN; i++) base[i] = 0;
|
||
|
|
for (i = 0; i < alphaSize; i++) base[length[i]+1]++;
|
||
|
|
|
||
|
|
for (i = 1; i < BZ_MAX_CODE_LEN; i++) base[i] += base[i-1];
|
||
|
|
|
||
|
|
for (i = 0; i < BZ_MAX_CODE_LEN; i++) limit[i] = 0;
|
||
|
|
vec = 0;
|
||
|
|
|
||
|
|
for (i = minLen; i <= maxLen; i++) {
|
||
|
|
vec += (base[i+1] - base[i]);
|
||
|
|
limit[i] = vec-1;
|
||
|
|
vec <<= 1;
|
||
|
|
}
|
||
|
|
for (i = minLen + 1; i <= maxLen; i++)
|
||
|
|
base[i] = ((limit[i-1] + 1) << 1) - base[i];
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
/*-------------------------------------------------------------*/
|
||
|
|
/*--- end huffman.c ---*/
|
||
|
|
/*-------------------------------------------------------------*/
|