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/*
* $Id: bit_io.h,v 1.17 2010/02/05 23:50:22 simakov Exp $
*
* EPSILON - wavelet image compression library.
* Copyright (C) 2006,2007,2010 Alexander Simakov, <xander@entropyware.info>
*
* This file is part of EPSILON
*
* EPSILON is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* EPSILON 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with EPSILON. If not, see <http://www.gnu.org/licenses/>.
*
* http://epsilon-project.sourceforge.net
*/
/** \file
*
* \brief Bit I/O
*
* This file contains bit I/O routines. */
#ifndef __BIT_IO_H__
#define __BIT_IO_H__
#ifdef __cplusplus
extern "C" {
#endif
/** \addtogroup bit_io Bit I/O */
/*@{*/
#include <common.h>
/** All bits are successfuly processed */
#define BIT_BUFFER_OK 0
/** Cannot write bits, output buffer is full */
#define BIT_BUFFER_OVERFLOW 1
/** Cannot read bits, input buffer is empty */
#define BIT_BUFFER_UNDERFLOW 2
/** Bit-buffer structure
*
* This structure represents bit-buffer. */
typedef struct bit_buffer_tag {
/** Start of buffer */
unsigned char *start;
/** End of buffer */
unsigned char *end;
/** Next input/output byte */
unsigned char *next;
/** Bit buffer */
unsigned long bits;
/** Pending bits */
int pending;
} bit_buffer;
/** Write one zero bit */
#define write_0(_bb) write_bits(_bb, 0UL, 1)
/** Write one unity bit */
#define write_1(_bb) write_bits(_bb, 1UL, 1)
/** Read one bit */
#define read_bit(_bb, _bit) read_bits(_bb, _bit, 1)
/** Initialize bit-buffer for reading or writting
*
* This function initializes bit-buffer \a bb for reading or
* writting bits.
*
* \param bb Bit-buffer to initialize
* \param buf Actual input/output buffer
* \param size Actual buffer size
*
* \return \c VOID */
void init_bits(bit_buffer *bb, unsigned char *buf, int size);
/** Write bits
*
* This function writes \a size least significant bits of
* the \a value to the bit-buffer \a bb.
*
* \note The function expects that \a size <= 24.
*
* \param bb Bit-buffer
* \param value Bits to write
* \param size Number of bits to write
*
* \return Either \ref BIT_BUFFER_OK or \ref BIT_BUFFER_OVERFLOW */
int write_bits(bit_buffer *bb, int value, int size);
/** Read bits
*
* This function reads \a size least significant bits
* from the bit-buffer \a bb into the \a value argument.
*
* \note Function expects that \a size <= 24.
*
* \param bb Bit-buffer
* \param value Location to store the bits
* \param size Number of bits to read
*
* \return Either \ref BIT_BUFFER_OK or \ref BIT_BUFFER_UNDERFLOW */
int read_bits(bit_buffer *bb, int *value, int size);
/** Flush bits
*
* This function flushes all pending bits if there are any.
*
* \param bb Bit-buffer
*
* \return Either \ref BIT_BUFFER_OK or \ref BIT_BUFFER_OVERFLOW */
int flush_bits(bit_buffer *bb);
/*@}*/
#ifdef __cplusplus
}
#endif
#endif /* __BIT_IO_H__ */
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