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authorThe Android Open Source Project <initial-contribution@android.com>2009-03-03 18:28:19 -0800
committerThe Android Open Source Project <initial-contribution@android.com>2009-03-03 18:28:19 -0800
commit48e1144df43616c7672ed98ed9da40a50622c18b (patch)
tree4b825dc642cb6eb9a060e54bf8d69288fbee4904 /huffman.c
parentd78fa13a44d08622d61d0df71e731de77021dcf1 (diff)
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auto import from //depot/cupcake/@135843
Diffstat (limited to 'huffman.c')
-rw-r--r--huffman.c205
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diff --git a/huffman.c b/huffman.c
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--- a/huffman.c
+++ /dev/null
@@ -1,205 +0,0 @@
-
-/*-------------------------------------------------------------*/
-/*--- Huffman coding low-level stuff ---*/
-/*--- huffman.c ---*/
-/*-------------------------------------------------------------*/
-
-/* ------------------------------------------------------------------
- This file is part of bzip2/libbzip2, a program and library for
- lossless, block-sorting data compression.
-
- bzip2/libbzip2 version 1.0.5 of 10 December 2007
- Copyright (C) 1996-2007 Julian Seward <jseward@bzip.org>
-
- Please read the WARNING, DISCLAIMER and PATENTS sections in the
- README file.
-
- This program is released under the terms of the license contained
- in the file LICENSE.
- ------------------------------------------------------------------ */
-
-
-#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 ---*/
-/*-------------------------------------------------------------*/