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/******************************************************************************
* *
* Copyright (C) 1992-1995 Tony Robinson *
* *
* See the file doc/LICENSE.shorten for conditions on distribution and usage *
* *
******************************************************************************/
/*
* $Id: vario.c,v 1.10 2004/05/04 02:26:36 jason Exp $
*/
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include "shorten.h"
#define MASKTABSIZE 33
ulong masktab[MASKTABSIZE];
void mkmasktab() {
int i;
ulong val = 0;
masktab[0] = val;
for(i = 1; i < MASKTABSIZE; i++) {
val <<= 1;
val |= 1;
masktab[i] = val;
}
}
void var_get_init(shn_file *this_shn)
{
mkmasktab();
this_shn->decode_state->getbuf = (uchar*) pmalloc((ulong) BUFSIZ,this_shn);
this_shn->decode_state->getbufp = this_shn->decode_state->getbuf;
this_shn->decode_state->nbyteget = 0;
this_shn->decode_state->gbuffer = 0;
this_shn->decode_state->nbitget = 0;
}
ulong word_get(shn_file *this_shn)
{
ulong buffer;
int bytes;
if(this_shn->decode_state->nbyteget < 4)
{
this_shn->vars.last_file_position = this_shn->vars.bytes_read;
bytes = deadbeef->fread((uchar*) this_shn->decode_state->getbuf, 1, BUFSIZ, this_shn->vars.fd);
this_shn->decode_state->nbyteget += bytes;
if(this_shn->decode_state->nbyteget < 4) {
shn_error_fatal(this_shn,"Premature EOF on compressed stream -\npossible corrupt or truncated file");
return (ulong)0;
}
this_shn->vars.bytes_read += bytes;
this_shn->decode_state->getbufp = this_shn->decode_state->getbuf;
}
buffer = (((slong) (this_shn->decode_state->getbufp[0])) << 24) | (((slong) (this_shn->decode_state->getbufp[1])) << 16) |
(((slong) (this_shn->decode_state->getbufp[2])) << 8) | ((slong) (this_shn->decode_state->getbufp[3]));
this_shn->decode_state->getbufp += 4;
this_shn->decode_state->nbyteget -= 4;
return(buffer);
}
slong uvar_get(int nbin,shn_file *this_shn)
{
slong result;
if (this_shn->vars.reading_function_code) {
this_shn->vars.last_file_position_no_really = this_shn->vars.last_file_position;
}
if(this_shn->decode_state->nbitget == 0)
{
this_shn->decode_state->gbuffer = word_get(this_shn);
if (this_shn->vars.fatal_error)
return (ulong)0;
this_shn->decode_state->nbitget = 32;
}
for(result = 0; !(this_shn->decode_state->gbuffer & (1L << --(this_shn->decode_state->nbitget))); result++)
{
if(this_shn->decode_state->nbitget == 0)
{
this_shn->decode_state->gbuffer = word_get(this_shn);
if (this_shn->vars.fatal_error)
return (ulong)0;
this_shn->decode_state->nbitget = 32;
}
}
while(nbin != 0)
{
if(this_shn->decode_state->nbitget >= nbin)
{
result = (result << nbin) | ((this_shn->decode_state->gbuffer >> (this_shn->decode_state->nbitget-nbin)) &masktab[nbin]);
this_shn->decode_state->nbitget -= nbin;
nbin = 0;
}
else
{
result = (result << this_shn->decode_state->nbitget) | (this_shn->decode_state->gbuffer & masktab[this_shn->decode_state->nbitget]);
this_shn->decode_state->gbuffer = word_get(this_shn);
if (this_shn->vars.fatal_error)
return (ulong)0;
nbin -= this_shn->decode_state->nbitget;
this_shn->decode_state->nbitget = 32;
}
}
return(result);
}
ulong ulong_get(shn_file *this_shn)
{
unsigned int nbit = uvar_get(ULONGSIZE,this_shn);
if (this_shn->vars.fatal_error)
return (ulong)0;
return(uvar_get(nbit,this_shn));
}
slong var_get(int nbin,shn_file *this_shn)
{
ulong uvar = uvar_get(nbin + 1,this_shn);
if (this_shn->vars.fatal_error)
return (slong)0;
if(uvar & 1) return((slong) ~(uvar >> 1));
else return((slong) (uvar >> 1));
}
void var_get_quit(shn_file *this_shn)
{
free((void *) this_shn->decode_state->getbuf);
this_shn->decode_state->getbuf = NULL;
}
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