theora-old/lib/blockmap.c

   1 /********************************************************************
   2  *                                                                  *
   3  * THIS FILE IS PART OF THE OggTheora SOFTWARE CODEC SOURCE CODE.   *
   4  * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS     *
   5  * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
   6  * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING.       *
   7  *                                                                  *
   8  * THE Theora SOURCE CODE IS COPYRIGHT (C) 2002-2003                *
   9  * by the Xiph.Org Foundation http://www.xiph.org/                  *
  10  *                                                                  *
  11  ********************************************************************
  12
  13   function:
  14   last mod: $Id$
  15
  16  ********************************************************************/
  17
  18 #include "codec_internal.h"
  19
  20 static void CreateMapping ( ogg_int32_t (*BlockMap)[4][4],
  21                             ogg_uint32_t FirstSB,
  22                             ogg_uint32_t FirstFrag, ogg_uint32_t HFrags,
  23                             ogg_uint32_t VFrags ){
  24   ogg_uint32_t i, j = 0;
  25   ogg_uint32_t xpos;
  26   ogg_uint32_t ypos;
  27   ogg_uint32_t SBrow, SBcol;
  28   ogg_uint32_t SBRows, SBCols;
  29   ogg_uint32_t MB, B;
  30
  31   ogg_uint32_t SB=FirstSB;
  32   ogg_uint32_t FragIndex=FirstFrag;
  33
  34   /* Set Super-Block dimensions */
  35   SBRows = VFrags/4 + ( VFrags%4 ? 1 : 0 );
  36   SBCols = HFrags/4 + ( HFrags%4 ? 1 : 0 );
  37
  38   /* Map each Super-Block */
  39   for ( SBrow=0; SBrow<SBRows; SBrow++ ){
  40     for ( SBcol=0; SBcol<SBCols; SBcol++ ){
  41       /* Y co-ordinate of Super-Block in Block units */
  42       ypos = SBrow<<2;
  43
  44       /* Map Blocks within this Super-Block */
  45       for ( i=0; (i<4) && (ypos<VFrags); i++, ypos++ ){
  46         /* X co-ordinate of Super-Block in Block units */
  47         xpos = SBcol<<2;
  48
  49         for ( j=0; (j<4) && (xpos<HFrags); j++, xpos++ ){
  50           if ( i<2 ){
  51             MB = ( j<2 ? 0 : 1 );
  52           }else{
  53             MB = ( j<2 ? 2 : 3 );
  54           }
  55
  56           if ( i%2 ){
  57             B = ( j%2 ? 3 : 2 );
  58           }else{
  59             B = ( j%2 ? 1 : 0 );
  60           }
  61
  62           /* Set mapping and move to next fragment */
  63           BlockMap[SB][MB][B] = FragIndex++;
  64         }
  65
  66         /* Move to first fragment in next row in Super-Block */
  67         FragIndex += HFrags-j;
  68       }
  69
  70       /* Move on to next Super-Block */
  71       SB++;
  72       FragIndex -= i*HFrags-j;
  73     }
  74
  75     /* Move to first Super-Block in next row */
  76     FragIndex += 3*HFrags;
  77   }
  78 }
  79
  80 void CreateBlockMapping ( ogg_int32_t  (*BlockMap)[4][4],
  81                           ogg_uint32_t YSuperBlocks,
  82                           ogg_uint32_t UVSuperBlocks,
  83                           ogg_uint32_t HFrags, ogg_uint32_t VFrags ) {
  84   ogg_uint32_t i, j;
  85
  86   for ( i=0; i<YSuperBlocks + UVSuperBlocks * 2; i++ ){
  87     for ( j=0; j<4; j++ ) {
  88       BlockMap[i][j][0] = -1;
  89       BlockMap[i][j][1] = -1;
  90       BlockMap[i][j][2] = -1;
  91       BlockMap[i][j][3] = -1;
  92     }
  93   }
  94
  95   CreateMapping ( BlockMap, 0, 0, HFrags, VFrags );
  96   CreateMapping ( BlockMap, YSuperBlocks, HFrags*VFrags, HFrags/2, VFrags/2 );
  97   CreateMapping ( BlockMap, YSuperBlocks + UVSuperBlocks, (HFrags*VFrags*5)/4,
  98                   HFrags/2, VFrags/2 );
  99 }
 100