subsystems/win32/win32k/eng/rlecomp.c

   1 /*
   2  * COPYRIGHT:         See COPYING in the top level directory
   3  * PROJECT:           ReactOS kernel
   4  * PURPOSE:           RLE compression
   5  * FILE:              subsystems/win32k/eng/rlecomp.c
   6  * PROGRAMER:         Jason Filby
   7  */
   8
   9 #include <win32k.h>
  10
  11 #define NDEBUG
  12 #include <debug.h>
  13
  14 enum Rle_EscapeCodes
  15 {
  16     RLE_EOL   = 0, /* End of line */
  17     RLE_END   = 1, /* End of bitmap */
  18     RLE_DELTA = 2  /* Delta */
  19 };
  20
  21 VOID DecompressBitmap(SIZEL Size, BYTE *CompressedBits, BYTE *UncompressedBits, LONG Delta, ULONG Format)
  22 {
  23     INT x = 0;
  24     INT y = Size.cy - 1;
  25     INT c;
  26     INT length;
  27     INT width;
  28     INT height = Size.cy - 1;
  29     BYTE *begin = CompressedBits;
  30     BYTE *bits = CompressedBits;
  31     BYTE *temp;
  32     INT shift = 0;
  33
  34     if (Format == BMF_4RLE)
  35         shift = 1;
  36     else if(Format != BMF_8RLE)
  37         return;
  38
  39     width = ((Size.cx + shift) >> shift);
  40
  41     _SEH2_TRY
  42     {
  43         while (y >= 0)
  44         {
  45             length = (*bits++) >> shift;
  46             if (length)
  47             {
  48                 c = *bits++;
  49                 while (length--)
  50                 {
  51                     if (x >= width) break;
  52                     temp = UncompressedBits + (((height - y) * Delta) + x);
  53                     x++;
  54                     *temp = c;
  55                 }
  56             }
  57             else
  58             {
  59                 length = *bits++;
  60                 switch (length)
  61                 {
  62                 case RLE_EOL:
  63                     x = 0;
  64                     y--;
  65                     break;
  66                 case RLE_END:
  67                     _SEH2_YIELD(return);
  68                 case RLE_DELTA:
  69                     x += (*bits++) >> shift;
  70                     y -= (*bits++) >> shift;
  71                     break;
  72                 default:
  73                     length = length >> shift;
  74                     while (length--)
  75                     {
  76                         c = *bits++;
  77                         if (x < width)
  78                         {
  79                             temp = UncompressedBits + (((height - y) * Delta) + x);
  80                             x++;
  81                             *temp = c;
  82                         }
  83                     }
  84                     if ((bits - begin) & 1)
  85                     {
  86                         bits++;
  87                     }
  88                 }
  89             }
  90         }
  91     }
  92     _SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER)
  93     {
  94         DPRINT1("Decoding error\n");
  95     }
  96     _SEH2_END;
  97
  98     return;
  99 }