/*

 * bitstream.c

 * Copyright (C) 2000-2002 Michel Lespinasse <walken@zoy.org>

 * Copyright (C) 1999-2000 Aaron Holtzman <aholtzma@ess.engr.uvic.ca>

 *

 * This file is part of a52dec, a free ATSC A-52 stream decoder.

 * See http://liba52.sourceforge.net/ for updates.

 *

 * a52dec 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.

 *

 * a52dec 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */

#include "config.h"

#include <inttypes.h>

#include "a52.h"

#include "a52_internal.h"

#include "bitstream.h"

#define BUFFER_SIZE 4096

void a52_bitstream_set_ptr (a52_state_t * state, uint8_t * buf)

{

    int align;

    align = (long)buf & 3;

    state->buffer_start = (uint32_t *) (buf - align);

    state->bits_left = 0;

    bitstream_get (state, align * 8);

}

static inline void bitstream_fill_current (a52_state_t * state)

{

    uint32_t tmp;

    tmp = *(state->buffer_start++);

    state->current_word = swab32 (tmp);

}

/*

 * The fast paths for _get is in the

 * bitstream.h header file so it can be inlined.

 *

 * The "bottom half" of this routine is suffixed _bh

 *

 * -ah

 */

uint32_t a52_bitstream_get_bh (a52_state_t * state, uint32_t num_bits)

{

    uint32_t result;

    num_bits -= state->bits_left;

    result = ((state->current_word << (32 - state->bits_left)) >>

	      (32 - state->bits_left));

    bitstream_fill_current (state);

    if (num_bits != 0)

	result = (result << num_bits) | (state->current_word >> (32 - num_bits));

    state->bits_left = 32 - num_bits;

    return result;

}

int32_t a52_bitstream_get_bh_2 (a52_state_t * state, uint32_t num_bits)

{

    int32_t result;

    num_bits -= state->bits_left;

    result = ((((int32_t)state->current_word) << (32 - state->bits_left)) >>

	      (32 - state->bits_left));

    bitstream_fill_current(state);

    if (num_bits != 0)

	result = (result << num_bits) | (state->current_word >> (32 - num_bits));

    state->bits_left = 32 - num_bits;

    return result;

}