139 lines
4.7 KiB
C
139 lines
4.7 KiB
C
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/**************************************************************************
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*
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* Copyright 2011 Christian König.
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* All Rights Reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sub license, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice (including the
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* next paragraph) shall be included in all copies or substantial portions
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* of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
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* IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
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* ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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**************************************************************************/
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/**
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* This file is based uppon slice_xvmc.c and vlc.h from the xine project,
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* which in turn is based on mpeg2dec. The following is the original copyright:
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*
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* Copyright (C) 2000-2002 Michel Lespinasse <walken@zoy.org>
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* Copyright (C) 1999-2000 Aaron Holtzman <aholtzma@ess.engr.uvic.ca>
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*
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* This file is part of mpeg2dec, a free MPEG-2 video stream decoder.
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* See http://libmpeg2.sourceforge.net/ for updates.
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*
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* mpeg2dec is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* mpeg2dec is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#ifndef vl_vlc_h
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#define vl_vlc_h
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struct vl_vlc
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{
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uint32_t buf; /* current 32 bit working set of buffer */
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int bits; /* used bits in working set */
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const uint8_t *ptr; /* buffer with stream data */
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const uint8_t *max; /* ptr+len of buffer */
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};
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static inline void
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vl_vlc_restart(struct vl_vlc *vlc)
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{
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vlc->buf = (vlc->ptr[0] << 24) | (vlc->ptr[1] << 16) | (vlc->ptr[2] << 8) | vlc->ptr[3];
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vlc->bits = -16;
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vlc->ptr += 4;
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}
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static inline void
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vl_vlc_init(struct vl_vlc *vlc, const uint8_t *data, unsigned len)
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{
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vlc->ptr = data;
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vlc->max = data + len;
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vl_vlc_restart(vlc);
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}
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static inline bool
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vl_vlc_getbyte(struct vl_vlc *vlc)
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{
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vlc->buf <<= 8;
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vlc->buf |= vlc->ptr[0];
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vlc->ptr++;
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return vlc->ptr < vlc->max;
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}
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#define vl_vlc_getword(vlc, shift) \
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do { \
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(vlc)->buf |= (((vlc)->ptr[0] << 8) | (vlc)->ptr[1]) << (shift); \
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(vlc)->ptr += 2; \
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} while (0)
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/* make sure that there are at least 16 valid bits in bit_buf */
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#define vl_vlc_needbits(vlc) \
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do { \
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if ((vlc)->bits >= 0) { \
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vl_vlc_getword(vlc, (vlc)->bits); \
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(vlc)->bits -= 16; \
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} \
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} while (0)
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/* make sure that the full 32 bit of the buffer are valid */
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static inline void
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vl_vlc_need32bits(struct vl_vlc *vlc)
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{
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vl_vlc_needbits(vlc);
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if (vlc->bits > -8) {
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unsigned n = -vlc->bits;
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vlc->buf <<= n;
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vlc->buf |= *vlc->ptr << 8;
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vlc->bits = -8;
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vlc->ptr++;
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}
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if (vlc->bits > -16) {
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unsigned n = -vlc->bits - 8;
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vlc->buf <<= n;
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vlc->buf |= *vlc->ptr;
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vlc->bits = -16;
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vlc->ptr++;
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}
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}
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/* remove num valid bits from bit_buf */
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#define vl_vlc_dumpbits(vlc, num) \
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do { \
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(vlc)->buf <<= (num); \
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(vlc)->bits += (num); \
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} while (0)
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/* take num bits from the high part of bit_buf and zero extend them */
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#define vl_vlc_ubits(vlc, num) (((uint32_t)((vlc)->buf)) >> (32 - (num)))
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/* take num bits from the high part of bit_buf and sign extend them */
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#define vl_vlc_sbits(vlc, num) (((int32_t)((vlc)->buf)) >> (32 - (num)))
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#endif /* vl_vlc_h */
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