/* * bitstream.c * Copyright (C) 2000-2001 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. * * Modified for use with MPlayer, changes contained in liba52_changes.diff. * detailed CVS changelog at http://www.mplayerhq.hu/cgi-bin/cvsweb.cgi/main/ * $Id$ * * 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 #ifdef ALT_BITSTREAM_READER int indx=0; uint32_t * buffer_start; #else static uint32_t * buffer_start; #endif uint32_t bits_left; uint32_t current_word; void bitstream_set_ptr (uint8_t * buf) { int align; align = (int)buf & 3; buffer_start = (uint32_t *) (buf - align); bits_left = 0; #ifdef ALT_BITSTREAM_READER indx=0; #endif bitstream_get (align * 8); } static inline void bitstream_fill_current(void) { uint32_t tmp; tmp = *(buffer_start++); 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 bitstream_get_bh(uint32_t num_bits) { uint32_t result; num_bits -= bits_left; result = (current_word << (32 - bits_left)) >> (32 - bits_left); bitstream_fill_current(); if(num_bits != 0) result = (result << num_bits) | (current_word >> (32 - num_bits)); bits_left = 32 - num_bits; return result; } int32_t bitstream_get_bh_2(uint32_t num_bits) { int32_t result; num_bits -= bits_left; result = (((int32_t)current_word) << (32 - bits_left)) >> (32 - bits_left); bitstream_fill_current(); if(num_bits != 0) result = (result << num_bits) | (current_word >> (32 - num_bits)); bits_left = 32 - num_bits; return result; }