f0d81ffd1c
which included commits to RCS files with non-trunk default branches. git-svn-id: svn://10.65.10.50/trunk@5403 c028cbd2-c16b-5b4b-a496-9718f37d4682
231 lines
6.4 KiB
C
Executable File
231 lines
6.4 KiB
C
Executable File
/*---------------------------------------------------------------------------
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unreduce.c
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The Reducing algorithm is actually a combination of two distinct algorithms.
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The first algorithm compresses repeated byte sequences, and the second al-
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gorithm takes the compressed stream from the first algorithm and applies a
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probabilistic compression method.
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* Copyright 1989 Samuel H. Smith; All rights reserved
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*
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* Do not distribute modified versions without my permission.
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* Do not remove or alter this notice or any other copyright notice.
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* If you use this in your own program you must distribute source code.
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* Do not use any of this in a commercial product.
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See the accompanying file "COPYING" in UnZip source and binary distributions
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for further information. This code is NOT used unless USE_SMITH_CODE is
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explicitly defined (==> COPYRIGHT_CLEAN is not defined).
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---------------------------------------------------------------------------*/
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#define UNZIP_INTERNAL
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#include "unzip.h" /* defines COPYRIGHT_CLEAN by default */
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#ifndef COPYRIGHT_CLEAN
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/**************************************/
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/* UnReduce Defines, Typedefs, etc. */
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/**************************************/
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#define DLE 144
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typedef uch f_array[64]; /* for followers[256][64] */
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/******************************/
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/* UnReduce Local Functions */
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/******************************/
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static void LoadFollowers OF((__GPRO__ f_array *followers, uch *Slen));
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/*******************************/
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/* UnReduce Global Constants */
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/*******************************/
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static shrint L_table[] =
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{0, 0x7f, 0x3f, 0x1f, 0x0f};
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static shrint D_shift[] =
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{0, 0x07, 0x06, 0x05, 0x04};
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static shrint D_mask[] =
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{0, 0x01, 0x03, 0x07, 0x0f};
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static shrint B_table[] =
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{8, 1, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 5,
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5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6,
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6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
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6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7,
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7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
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7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
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7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
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7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
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8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
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8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
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8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
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8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
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8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
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8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
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8, 8, 8, 8};
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/*************************/
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/* Function unreduce() */
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/*************************/
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void unreduce(__G) /* expand probabilistically reduced data */
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__GDEF
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{
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register int lchar = 0;
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shrint nchar;
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shrint ExState = 0;
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shrint V = 0;
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shrint Len = 0;
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long s = G.ucsize; /* number of bytes left to decompress */
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unsigned w = 0; /* position in output window slide[] */
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unsigned u = 1; /* true if slide[] unflushed */
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uch Slen[256];
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f_array *followers = (f_array *)(slide + 0x4000);
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int factor = G.lrec.compression_method - 1;
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LoadFollowers(__G__ followers, Slen);
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while (s > 0 /* && (!zipeof) */) {
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if (Slen[lchar] == 0)
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READBITS(8, nchar) /* ; */
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else {
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READBITS(1, nchar) /* ; */
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if (nchar != 0)
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READBITS(8, nchar) /* ; */
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else {
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shrint follower;
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int bitsneeded = B_table[Slen[lchar]];
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READBITS(bitsneeded, follower) /* ; */
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nchar = followers[lchar][follower];
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}
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}
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/* expand the resulting byte */
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switch (ExState) {
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case 0:
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if (nchar != DLE) {
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s--;
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slide[w++] = (uch)nchar;
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if (w == 0x4000) {
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flush(__G__ slide, (ulg)w, 0);
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w = u = 0;
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}
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}
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else
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ExState = 1;
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break;
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case 1:
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if (nchar != 0) {
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V = nchar;
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Len = V & L_table[factor];
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if (Len == L_table[factor])
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ExState = 2;
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else
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ExState = 3;
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} else {
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s--;
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slide[w++] = DLE;
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if (w == 0x4000)
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{
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flush(__G__ slide, (ulg)w, 0);
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w = u = 0;
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}
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ExState = 0;
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}
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break;
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case 2:{
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Len += nchar;
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ExState = 3;
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}
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break;
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case 3:{
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register unsigned e;
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register unsigned n = Len + 3;
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register unsigned d = w - ((((V >> D_shift[factor]) &
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D_mask[factor]) << 8) + nchar + 1);
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s -= n;
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do {
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n -= (e = (e = 0x4000 - ((d &= 0x3fff) > w ? d : w)) > n ?
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n : e);
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if (u && w <= d)
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{
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memzero(slide + w, e);
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w += e;
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d += e;
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}
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else
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if (w - d < e) /* (assume unsigned comparison) */
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do { /* slow to avoid memcpy() overlap */
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slide[w++] = slide[d++];
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} while (--e);
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else
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{
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memcpy(slide + w, slide + d, e);
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w += e;
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d += e;
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}
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if (w == 0x4000)
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{
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flush(__G__ slide, (ulg)w, 0);
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w = u = 0;
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}
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} while (n);
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ExState = 0;
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}
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break;
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}
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/* store character for next iteration */
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lchar = nchar;
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}
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/* flush out slide */
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flush(__G__ slide, (ulg)w, 0);
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}
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/******************************/
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/* Function LoadFollowers() */
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/******************************/
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static void LoadFollowers(__G__ followers, Slen)
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__GDEF
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f_array *followers;
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uch *Slen;
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{
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register int x;
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register int i;
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for (x = 255; x >= 0; x--) {
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READBITS(6, Slen[x]) /* ; */
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for (i = 0; (uch)i < Slen[x]; i++)
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READBITS(8, followers[x][i]) /* ; */
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}
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}
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#endif /* !COPYRIGHT_CLEAN */
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