/*
 * @(#) fbitio.c - File bit I/O support functions library (source).
 * (c) 1998 Ivan Maidanski <ivmai@chat.ru> http://ivmai.chat.ru
 * Freeware function library source. All rights reserved.
 **
 * Language: ANSI C
 * Tested with: Watcom C 16/32 v11.0
 * Last modified: 1998-06-12 19:10:00 GMT+04:00
 */

#include "fbitio.h" /* header file */

#include <limits.h> /* CHAR_BIT */
#include <stdio.h> /* NULL, EOF, FILE, fgetc(), fputc(), feof() */

/* implementation section */

int fbitput(FILE *f, unsigned char *pbitbuf, int bit)
{
 if (pbitbuf==NULL)
  return fputc(bit? 1 : 0,f);
 if (!*pbitbuf)
  *pbitbuf=1<<(CHAR_BIT-1);
 if (*pbitbuf&1)
 {
  *pbitbuf>>=1;
  if (bit)
   *pbitbuf|=1<<(CHAR_BIT-1);
  bit=fputc(*pbitbuf,f);
  *pbitbuf=0;
 }
  else
  {
   *pbitbuf>>=1;
   if (bit)
    *pbitbuf|=1<<(CHAR_BIT-1);
   bit=0;
  }
 return bit;
}

int fbitflush(FILE *f, unsigned char *pbitbuf)
{
 int res;
 if (pbitbuf==NULL || !*pbitbuf)
  return 0;
 res=*pbitbuf!=(1<<(CHAR_BIT-1));
 while (!(*pbitbuf&1))
  *pbitbuf>>=1;
 if (res)
  res=fputc(*pbitbuf>>1,f);
 *pbitbuf=0;
 return res;
}

int fbitget(FILE *f, unsigned char *pbitbuf)
{
 int bit;
 if (pbitbuf==NULL)
  return (bit=fgetc(f))==EOF? EOF : (bit? 1 : 0);
 bit=*pbitbuf;
 if (!(*pbitbuf>>=1))
 {
  if ((bit=fgetc(f))==EOF)
   return EOF;
  *pbitbuf=(((unsigned char)bit)>>1)|(1<<(CHAR_BIT-1));
 }
 return bit&1;
}

int fbiteof(FILE *f, unsigned char *pbitbuf)
{
 return feof(f) && (pbitbuf==NULL || *pbitbuf<=1);
}

int fbitvalput(FILE *f, unsigned char *pbitbuf,
               unsigned long value, unsigned long maxval)
{
 for (;maxval;value>>=1,maxval>>=1)
  if (fbitput(f,pbitbuf,value&1? 1 : 0)==EOF)
   return EOF;
 return 0;
}

int fbitvalget(FILE *f, unsigned char *pbitbuf,
               unsigned long *pvalue, unsigned long maxval)
{
 int bit;
 unsigned long mask;
 if (pvalue==NULL)
  return 0;
 for (*pvalue=0,mask=1;mask && maxval>=mask;mask<<=1)
  if ((bit=fbitget(f,pbitbuf))==EOF)
   return EOF;
   else if (bit)
    *pvalue|=mask;
 bit=*pvalue>maxval;
 if (bit)
  *pvalue-=maxval+1;
 return bit;
}