140 lines
3.0 KiB
C++
140 lines
3.0 KiB
C++
/*
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* vario.cpp
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* shorten_decoder
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*
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* Created by Alex Lagutin on Tue Jul 09 2002.
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* Copyright (c) 2002 Eckysoft All rights reserved.
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*
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*/
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/******************************************************************************
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* *
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* Copyright (C) 1992-1995 Tony Robinson *
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* *
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* See the file doc/LICENSE.shorten for conditions on distribution and usage *
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* *
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******************************************************************************/
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/*
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* $Id: vario.c,v 1.6 2001/12/30 05:12:04 jason Exp $
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*/
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#include "shn_reader.h"
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void shn_reader::var_get_init()
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{
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int i;
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ulong val = 0;
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masktab[0] = val;
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for (i = 1; i < MASKTABSIZE; i++)
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{
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val <<= 1;
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val |= 1;
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masktab[i] = val;
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}
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mDecodeState.getbuf = (uchar *) malloc(BUFSIZ);
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mDecodeState.getbufp = mDecodeState.getbuf;
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mDecodeState.nbyteget = 0;
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mDecodeState.gbuffer = 0;
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mDecodeState.nbitget = 0;
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if (!mDecodeState.getbuf)
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mFatalError = true;
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}
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ulong shn_reader::word_get()
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{
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ulong buffer;
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if (mDecodeState.nbyteget < 4)
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{
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mDecodeState.nbyteget += fread(mDecodeState.getbuf, 1, BUFSIZ, mFP);
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if (mDecodeState.nbyteget < 4)
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{
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mFatalError = true;
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return 0;
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}
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mDecodeState.getbufp = mDecodeState.getbuf;
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}
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buffer = (((long) (mDecodeState.getbufp[0])) << 24) | (((long) (mDecodeState.getbufp[1])) << 16)
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| (((long) (mDecodeState.getbufp[2])) << 8) | ((long) (mDecodeState.getbufp[3]));
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mDecodeState.getbufp += 4;
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mDecodeState.nbyteget -= 4;
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return buffer;
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}
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long shn_reader::uvar_get(int nbin)
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{
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long result;
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if (!mDecodeState.nbitget)
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{
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mDecodeState.gbuffer = word_get();
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if (mFatalError)
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return 0;
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mDecodeState.nbitget = 32;
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}
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for (result = 0; !(mDecodeState.gbuffer & (1L << --(mDecodeState.nbitget))); result++)
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{
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if (!mDecodeState.nbitget)
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{
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mDecodeState.gbuffer = word_get();
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if (mFatalError)
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return 0;
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mDecodeState.nbitget = 32;
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}
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}
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while (nbin)
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{
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if(mDecodeState.nbitget >= nbin)
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{
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result = (result << nbin) | ((mDecodeState.gbuffer >> (mDecodeState.nbitget-nbin)) & masktab[nbin]);
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mDecodeState.nbitget -= nbin;
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nbin = 0;
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}
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else
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{
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result = (result << mDecodeState.nbitget) | (mDecodeState.gbuffer & masktab[mDecodeState.nbitget]);
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mDecodeState.gbuffer = word_get();
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if (mFatalError)
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return 0;
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nbin -= mDecodeState.nbitget;
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mDecodeState.nbitget = 32;
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}
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}
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return result;
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}
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ulong shn_reader::ulong_get()
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{
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uint nbit = uvar_get(ULONGSIZE);
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if (mFatalError)
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return 0;
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return uvar_get(nbit);
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}
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long shn_reader::var_get(int nbin)
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{
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ulong uvar = uvar_get(nbin + 1);
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if (mFatalError)
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return 0;
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return ((uvar & 1) ? ((long) ~(uvar >> 1)) : ((long) (uvar >> 1)));
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}
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void shn_reader::var_get_quit()
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{
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free(mDecodeState.getbuf);
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mDecodeState.getbuf = NULL;
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}
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