/* common.c - Don Yang (uguu.org)

   09/11/01
                                                                           */

#include<assert.h>
#include<stdio.h>
#include"common.h"


/* Ring buffer */
BYTE RingBuffer[BUFFER_SIZE];
int ProcOffset, LimitOffset;
int FileSize, iChecksum, oChecksum;

/***************************************************************** GetByte */
DWORD GetByte(int absoffset, FILE *infile)
{
   int byte;

   while( absoffset >= LimitOffset )
   {
      if( (byte = fgetc(infile)) == EOF )
      {
         FileSize = LimitOffset++;
         return INPUT_EOF;
      }
      iChecksum ^= (int)byte;
      RingBuffer[(LimitOffset++) & BUFFER_MASK] = (BYTE)byte;
   }
   if( absoffset >= FileSize )
      return INPUT_EOF;

   return (DWORD)RingBuffer[absoffset & BUFFER_MASK];

} /* GetByte() */

/***************************************************************** PutByte */
void PutByte(BYTE byte, FILE *outfile)
{
   oChecksum ^= (int)byte;
   (void)fputc((int)byte, outfile);

} /* PutByte() */

/***************************************************************** PutWord */
void PutWord(WORD word, FILE *outfile)
{
   oChecksum ^= (int)(word & 0xff);
   oChecksum ^= (int)(word >> 8);
   (void)fputc((int)(word & 0xff), outfile);
   (void)fputc((int)(word >> 8), outfile);

} /* PutWord() */