/*  *  bitstream.c * *	Copyright (C) Aaron Holtzman - May 1999 * *  This file is part of ac3dec, a free Dolby AC-3 stream decoder. *	 *  ac3dec 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, or (at your option) *  any later version. *    *  ac3dec 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 GNU Make; see the file COPYING.  If not, write to *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  * */#include <stdlib.h>#include <stdio.h>#include "ac3.h"#include "decode.h"#include "crc.h"#include "bitstream.h"//My vego-matic endian swapping routine#define SWAP_ENDIAN32(x)  ((((uint_8*)&x)[0] << 24) |  \                         (((uint_8*)&x)[1] << 16) |  \                         (((uint_8*)&x)[2] << 8) |   \                         ((uint_8*)&x)[3])           static void bitstream_load(bitstream_t *bs);/* Fetches 1-32 bits from the file opened in bitstream_open */uint_32bitstream_get(bitstream_t *bs,uint_32 num_bits){	uint_32 result;	uint_32 bits_read;	uint_32 bits_to_go;	if(num_bits == 0)		return 0;#ifdef DO_NIST        result = inputstream->get_bits(num_bits);#else	bits_read = num_bits > bs->bits_left ? bs->bits_left : num_bits; 	result = bs->current_word  >> (32 - bits_read);	bs->current_word <<= bits_read;	bs->bits_left -= bits_read;	if(bs->bits_left == 0)		bitstream_load(bs);	if (bits_read < num_bits)	{		bits_to_go = num_bits - bits_read;		result <<= bits_to_go;		result |= bs->current_word  >> (32 - bits_to_go);		bs->current_word <<= bits_to_go;		bs->bits_left -= bits_to_go;	}		bs->total_bits_read += num_bits;#endif	crc_process(result,num_bits);	return result;}#ifndef DO_NISTstatic voidbitstream_load(bitstream_t *bs){	int bytes_read;	bytes_read = fread(&bs->current_word,1,4,bs->file);	bs->current_word = SWAP_ENDIAN32(bs->current_word);	bs->bits_left = bytes_read * 8;	//FIXME finishing up the stream isn't done too gracefully	if (bytes_read < 4)		bs->done = 1;}/* Opens a bitstream for use in bitstream_get */bitstream_t*bitstream_open(FILE *file){	bitstream_t *bs;		if(!file)		return 0;	bs = malloc(sizeof(bitstream_t));	if(!bs)		return 0;	bs->done = 0;	/* Read in the first 32 bit word and initialize the structure */	bs->file = file;	bitstream_load(bs);	return bs;}int bitstream_done(bitstream_t *bs){	return (bs->done);}void bitstream_close(bitstream_t *bs){	if(bs->file)		fclose(bs->file);	free(bs);}#endif