vl_vlc.h revision 49967950a56de276ffcbaea80acbc9f5bd3207bc 
1/**************************************************************************
2 *
3 * Copyright 2011 Christian König.
4 * All Rights Reserved.
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the
8 * "Software"), to deal in the Software without restriction, including
9 * without limitation the rights to use, copy, modify, merge, publish,
10 * distribute, sub license, and/or sell copies of the Software, and to
11 * permit persons to whom the Software is furnished to do so, subject to
12 * the following conditions:
13 *
14 * The above copyright notice and this permission notice (including the
15 * next paragraph) shall be included in all copies or substantial portions
16 * of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
19 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
20 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
21 * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
22 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
23 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
24 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
25 *
26 **************************************************************************/
27
28/**
29 * This file is based uppon slice_xvmc.c and vlc.h from the xine project,
30 * which in turn is based on mpeg2dec. The following is the original copyright:
31 *
32 * Copyright (C) 2000-2002 Michel Lespinasse <walken@zoy.org>
33 * Copyright (C) 1999-2000 Aaron Holtzman <aholtzma@ess.engr.uvic.ca>
34 *
35 * This file is part of mpeg2dec, a free MPEG-2 video stream decoder.
36 * See http://libmpeg2.sourceforge.net/ for updates.
37 *
38 * mpeg2dec is free software; you can redistribute it and/or modify
39 * it under the terms of the GNU General Public License as published by
40 * the Free Software Foundation; either version 2 of the License, or
41 * (at your option) any later version.
42 *
43 * mpeg2dec is distributed in the hope that it will be useful,
44 * but WITHOUT ANY WARRANTY; without even the implied warranty of
45 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
46 * GNU General Public License for more details.
47 *
48 * You should have received a copy of the GNU General Public License
49 * along with this program; if not, write to the Free Software
50 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
51 */
52
53#ifndef vl_vlc_h
54#define vl_vlc_h
55
56#include "pipe/p_compiler.h"
57
58struct vl_vlc
59{
60   uint32_t buf; /* current 32 bit working set of buffer */
61   int bits;     /* used bits in working set */
62   const uint8_t *ptr; /* buffer with stream data */
63   const uint8_t *max; /* ptr+len of buffer */
64};
65
66static INLINE void
67vl_vlc_restart(struct vl_vlc *vlc)
68{
69   vlc->buf = (vlc->ptr[0] << 24) | (vlc->ptr[1] << 16) | (vlc->ptr[2] << 8) | vlc->ptr[3];
70   vlc->bits = -16;
71   vlc->ptr += 4;
72}
73
74static INLINE void
75vl_vlc_init(struct vl_vlc *vlc, const uint8_t *data, unsigned len)
76{
77   vlc->ptr = data;
78   vlc->max = data + len;
79   vl_vlc_restart(vlc);
80}
81
82static INLINE bool
83vl_vlc_getbyte(struct vl_vlc *vlc)
84{
85   vlc->buf <<= 8;
86   vlc->buf |= vlc->ptr[0];
87   vlc->ptr++;
88   return vlc->ptr < vlc->max;
89}
90
91#define vl_vlc_getword(vlc, shift)                                      \
92do {                                                                    \
93   (vlc)->buf |= (((vlc)->ptr[0] << 8) | (vlc)->ptr[1]) << (shift);     \
94   (vlc)->ptr += 2;                                                     \
95} while (0)
96
97/* make sure that there are at least 16 valid bits in bit_buf */
98#define vl_vlc_needbits(vlc)                    \
99do {                                            \
100    if ((vlc)->bits >= 0) {                      \
101	vl_vlc_getword(vlc, (vlc)->bits);       \
102	(vlc)->bits -= 16;                      \
103    }                                           \
104} while (0)
105
106/* make sure that the full 32 bit of the buffer are valid */
107static INLINE void
108vl_vlc_need32bits(struct vl_vlc *vlc)
109{
110   vl_vlc_needbits(vlc);
111   if (vlc->bits > -8) {
112      unsigned n = -vlc->bits;
113      vlc->buf <<= n;
114      vlc->buf |= *vlc->ptr << 8;
115      vlc->bits = -8;
116      vlc->ptr++;
117   }
118   if (vlc->bits > -16) {
119      unsigned n = -vlc->bits - 8;
120      vlc->buf <<= n;
121      vlc->buf |= *vlc->ptr;
122      vlc->bits = -16;
123      vlc->ptr++;
124   }
125}
126
127/* remove num valid bits from bit_buf */
128#define vl_vlc_dumpbits(vlc, num)       \
129do {					\
130    (vlc)->buf <<= (num);		\
131    (vlc)->bits += (num);		\
132} while (0)
133
134/* take num bits from the high part of bit_buf and zero extend them */
135#define vl_vlc_ubits(vlc, num) (((uint32_t)((vlc)->buf)) >> (32 - (num)))
136
137/* take num bits from the high part of bit_buf and sign extend them */
138#define vl_vlc_sbits(vlc, num) (((int32_t)((vlc)->buf)) >> (32 - (num)))
139
140#endif /* vl_vlc_h */
141