source: trunk/indexers/mg/lib/bitio_m_stdio.h@ 3745

/**************************************************************************
 *
 * bitio_m_stdio.h -- Macros for bitio to a file
 * Copyright (C) 1994  Neil Sharman
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * $Id: bitio_m_stdio.h 3745 2003-02-20 21:20:24Z mdewsnip $
 *
 **************************************************************************
 *
 *  This file contains macros for doing bitwise input and output on a FILE*.
 *  With these routines you cannot mix reads and writes on the FILE,
 *  or multiple writes, at the same time and guarantee them to work, also you 
 *  cannot seek to a point and do a write. The decode routine can detect when
 *  you run off the end of the file and will produce an approate error message.
 *
 *
 **************************************************************************/

#ifndef H_BITIO_M_STDIO
#define H_BITIO_M_STDIO

typedef struct stdio_bitio_state
  {
    FILE *File;
    unsigned char Buff;
    unsigned char Btg;
  }
stdio_bitio_state;



#ifndef DECODE_ERROR
#define DECODE_ERROR (fprintf(stderr,"Unexpected EOF in \"%s\" on line %d\n",\
                __FILE__, __LINE__), exit(1))
#endif



#define ENCODE_START(f)                         \
  {                                 \
    FILE *__outfile = f;                        \
    register unsigned char __buff = 0;                  \
    register unsigned char __btg = sizeof(__buff)*8;

#define ENCODE_CONTINUE(b)                      \
  {                                 \
    FILE *__outfile = (b).File;                     \
    register unsigned char __buff = (b).Buff;               \
    register unsigned char __btg = (b).Btg;

#define ENCODE_BIT(b)                           \
  do {                                  \
    __btg--;                                \
    if (b) __buff |= (1 << __btg);                  \
    if (!__btg)                             \
      {                                 \
    putc(__buff, __outfile);                    \
    __buff = 0;                         \
    __btg = sizeof(__buff)*8;                   \
      }                                 \
  } while(0)

#define ENCODE_PAUSE(b)                         \
    (b).File = __outfile;                       \
    (b).Buff = __buff;                          \
    (b).Btg =  __btg;                           \
  }

#define ENCODE_DONE                         \
    if (__btg != sizeof(__buff)*8)                  \
      putc(__buff,__outfile);                       \
  }


#define DECODE_START(f)                         \
  {                                 \
    FILE *__infile = f;                         \
    register unsigned char __buff = 0;                  \
    register unsigned char __btg = 0;

#define DECODE_CONTINUE(b)                      \
  {                                 \
    FILE *__infile = (b).File;                      \
    register unsigned char __buff = (b).Buff;               \
    register unsigned char __btg = (b).Btg;

#define DECODE_ADD_FF(b)                        \
  do {                                  \
    if (!__btg)                             \
      {                                 \
    register int val = getc(__infile);              \
    __buff = val == EOF ? 0xff : val;               \
    __btg = sizeof(__buff)*8;                   \
      }                                 \
    (b) += (b) + ((__buff >> --__btg) & 1);             \
  } while(0)

#define DECODE_ADD_00(b)                        \
  do {                                  \
    if (!__btg)                             \
      {                                 \
    register int val = getc(__infile);              \
    __buff = val == EOF ? 0xff : val;               \
    __btg = sizeof(__buff)*8;                   \
      }                                 \
    (b) += (b) + ((__buff >> --__btg) & 1);             \
  } while(0)

#define DECODE_BIT (__btg ? (__buff >> --__btg) & 1 :           \
   (__buff = getc(__infile), (feof(__infile) ?              \
    (DECODE_ERROR, 0) :                         \
    (__btg = sizeof(__buff)*8, (__buff >> --__btg) & 1))))

#define DECODE_DONE ;                       \
  }

#define DECODE_PAUSE(b)                         \
    (b).File = __infile;                        \
    (b).Buff = __buff;                          \
    (b).Btg =  __btg;                           \
  }


#define DECODE_SEEK(pos)                        \
  do {                                  \
    register long __new_pos = (pos);                    \
    fseek(__infile, __new_pos >> 3, 0);                 \
    __buff = getc(__infile);                        \
    __btg = 8 - (__new_pos&7);                      \
    }                                   \
  while(0)

#endif