src/gallium/auxiliary/vl/vl_vlc.h

   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 struct vl_vlc
  57 {
  58    uint32_t buf; /* current 32 bit working set of buffer */
  59    int bits;     /* used bits in working set */
  60    const uint8_t *ptr; /* buffer with stream data */
  61    const uint8_t *max; /* ptr+len of buffer */
  62 };
  63
  64 static inline void
  65 vl_vlc_restart(struct vl_vlc *vlc)
  66 {
  67    vlc->buf = (vlc->ptr[0] << 24) | (vlc->ptr[1] << 16) | (vlc->ptr[2] << 8) | vlc->ptr[3];
  68    vlc->bits = -16;
  69    vlc->ptr += 4;
  70 }
  71
  72 static inline void
  73 vl_vlc_init(struct vl_vlc *vlc, const uint8_t *data, unsigned len)
  74 {
  75    vlc->ptr = data;
  76    vlc->max = data + len;
  77    vl_vlc_restart(vlc);
  78 }
  79
  80 static inline bool
  81 vl_vlc_getbyte(struct vl_vlc *vlc)
  82 {
  83    vlc->buf <<= 8;
  84    vlc->buf |= vlc->ptr[0];
  85    vlc->ptr++;
  86    return vlc->ptr < vlc->max;
  87 }
  88
  89 #define vl_vlc_getword(vlc, shift)                                      \
  90 do {                                                                    \
  91    (vlc)->buf |= (((vlc)->ptr[0] << 8) | (vlc)->ptr[1]) << (shift);     \
  92    (vlc)->ptr += 2;                                                     \
  93 } while (0)
  94
  95 /* make sure that there are at least 16 valid bits in bit_buf */
  96 #define vl_vlc_needbits(vlc)                    \
  97 do {                                            \
  98     if ((vlc)->bits >= 0) {                      \
  99         vl_vlc_getword(vlc, (vlc)->bits);       \
 100         (vlc)->bits -= 16;                      \
 101     }                                           \
 102 } while (0)
 103
 104 /* make sure that the full 32 bit of the buffer are valid */
 105 static inline void
 106 vl_vlc_need32bits(struct vl_vlc *vlc)
 107 {
 108    vl_vlc_needbits(vlc);
 109    if (vlc->bits > -8) {
 110       unsigned n = -vlc->bits;
 111       vlc->buf <<= n;
 112       vlc->buf |= *vlc->ptr << 8;
 113       vlc->bits = -8;
 114       vlc->ptr++;
 115    }
 116    if (vlc->bits > -16) {
 117       unsigned n = -vlc->bits - 8;
 118       vlc->buf <<= n;
 119       vlc->buf |= *vlc->ptr;
 120       vlc->bits = -16;
 121       vlc->ptr++;
 122    }
 123 }
 124
 125 /* remove num valid bits from bit_buf */
 126 #define vl_vlc_dumpbits(vlc, num)       \
 127 do {                                    \
 128     (vlc)->buf <<= (num);               \
 129     (vlc)->bits += (num);               \
 130 } while (0)
 131
 132 /* take num bits from the high part of bit_buf and zero extend them */
 133 #define vl_vlc_ubits(vlc, num) (((uint32_t)((vlc)->buf)) >> (32 - (num)))
 134
 135 /* take num bits from the high part of bit_buf and sign extend them */
 136 #define vl_vlc_sbits(vlc, num) (((int32_t)((vlc)->buf)) >> (32 - (num)))
 137
 138 #endif /* vl_vlc_h */