bitbuf.h

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/*! \file bitbuf.h \brief Multipurpose bit buffer structure and methods. */
//*****************************************************************************
//
// File Name    : 'bitbuf.c'
// Title        : Multipurpose bit buffer structure and methods
// Author       : Pascal Stang - Copyright (C) 2001-2002
// Created      : 7/10/2002
// Revised      : 7/10/2002
// Version      : 0.5
// Target MCU   : any
// Editor Tabs  : 4
//
/// \ingroup general
/// \defgroup bitbuf Generic Bit-Buffer Structure and Function Library (bitbuf.c)
/// \code #include "bitbuf.h" \endcode
/// \par Overview
///     This bit-buffer structure provides an easy and efficient way to store and
///     process bits. You can create as many bit buffers as you like (within
///     memory limits), and then use this common set of functions to access each
///     buffer. Supported functions include sequential getting and storing of
///     bits, array-like get, buffer flush (dump data), and reset-to-beginning.
///     This buffer is not dynamically allocated, it has a user-defined fixed 
///     maximum size.
///
// This code is distributed under the GNU Public License
//      which can be found at http://www.gnu.org/licenses/gpl.txt
//
//*****************************************************************************
//@{

#ifndef BITBUF_H
#define BITBUF_H

// structure/typdefs

// the BitBuffer structure
typedef struct struct_BitBuf
{
    unsigned char *dataptr;         // the physical memory address where the buffer is stored
    unsigned short  size;           // the allocated byte size of the buffer
    unsigned short bytePos;         // current byte position
    unsigned short bitPos;          // current bit position
    unsigned short datalength;      // the length of the data (in bits) currently in the buffer
    unsigned short dataindex;       // the index (in bits) into the buffer where the data starts
} BitBuf;

// function prototypes

//! initialize a buffer to start at a given address and have given size
void bitbufInit(BitBuf* bitBuffer, unsigned char *start, unsigned short bytesize);

//! get the bit at the current position in the buffer
unsigned char bitbufGet(BitBuf* bitBuffer);

//! get a bit at the specified index in the buffer (kind of like array access)
// ** note: this does not remove/delete the bit that was read
unsigned char bitbufGetAtIndex(BitBuf* bitBuffer, unsigned short bitIndex);

//! store a bit at the current position in the buffer
void bitbufStore(BitBuf* bitBuffer, unsigned char bit);

//! return the number of bits in the buffer
unsigned short bitbufGetDataLength(BitBuf* bitBuffer);

// check if the buffer is full/not full (returns non-zero value if not full)
//unsigned char  bitbufIsNotFull(cBuffer* buffer);

//! resets the read/write position of the buffer to beginning
void bitbufReset(BitBuf* bitBuffer);

//! flush (clear) the contents of the buffer
void bitbufFlush(BitBuf* bitBuffer);

#endif
//@}

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