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decode.c

/*$Source: /usr/home/dhesi/zoo/RCS/decode.c,v $*/
/*$Id: decode.c,v 1.6 91/07/09 01:39:49 dhesi Exp $*/
/***********************************************************
      decode.c

Adapted from "ar" archiver written by Haruhiko Okumura.
***********************************************************/

#include "options.h"
#include "zoo.h"
#include "ar.h"
#include "lzh.h"

extern int decoded;           /* from huf.c */

static int j;  /* remaining bytes to copy */

void decode_start()
{
      huf_decode_start();
      j = 0;
      decoded = 0;
}

/*
decodes; returns no. of chars decoded 
*/

int decode(count, buffer)
uint count;
uchar buffer[];
      /* The calling function must keep the number of
         bytes to be processed.  This function decodes
         either 'count' bytes or 'DICSIZ' bytes, whichever
         is smaller, into the array 'buffer[]' of size
         'DICSIZ' or more.
         Call decode_start() once for each new file
         before calling this function. */
{
      static uint i;
      uint r, c;

      r = 0;
      while (--j >= 0) {
            buffer[r] = buffer[i];
            i = (i + 1) & (DICSIZ - 1);
            if (++r == count)
                  return r;
      }
      for ( ; ; ) {
            c = decode_c();
            if (decoded)
                  return r;
            if (c <= UCHAR_MAX) {
                  buffer[r] = c;
                  if (++r == count) 
                        return r;
            } else {
                  j = c - (UCHAR_MAX + 1 - THRESHOLD);
                  i = (r - decode_p() - 1) & (DICSIZ - 1);
                  while (--j >= 0) {
                        buffer[r] = buffer[i];
                        i = (i + 1) & (DICSIZ - 1);
                        if (++r == count)
                              return r;
                  }
            }
      }
}

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