reactos/subsystems/win32/win32k/eng/rlecomp.c

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/*
* COPYRIGHT: See COPYING in the top level directory
* PROJECT: ReactOS kernel
* PURPOSE: RLE compression
* FILE: subsystems/win32k/eng/rlecomp.c
* PROGRAMER: Jason Filby
*/
#include <win32k.h>
#define NDEBUG
#include <debug.h>
enum Rle_EscapeCodes
{
RLE_EOL = 0, /* End of line */
RLE_END = 1, /* End of bitmap */
RLE_DELTA = 2 /* Delta */
};
VOID Decompress4bpp(SIZEL Size, BYTE *CompressedBits, BYTE *UncompressedBits, LONG Delta)
{
int x = 0;
int y = Size.cy - 1;
int c;
int length;
int width = ((Size.cx+1)/2);
int height = Size.cy - 1;
BYTE *begin = CompressedBits;
BYTE *bits = CompressedBits;
BYTE *temp;
while (y >= 0)
{
length = *bits++ / 2;
if (length)
{
c = *bits++;
while (length--)
{
if (x >= width) break;
temp = UncompressedBits + (((height - y) * Delta) + x);
x++;
*temp = c;
}
}
else
{
length = *bits++;
switch (length)
{
case RLE_EOL:
x = 0;
y--;
break;
case RLE_END:
return;
case RLE_DELTA:
x += (*bits++)/2;
y -= (*bits++)/2;
break;
default:
length /= 2;
while (length--)
{
c = *bits++;
if (x < width)
{
temp = UncompressedBits + (((height - y) * Delta) + x);
x++;
*temp = c;
}
}
if ((bits - begin) & 1)
{
bits++;
}
}
}
}
}
VOID Decompress8bpp(SIZEL Size, BYTE *CompressedBits, BYTE *UncompressedBits, LONG Delta)
{
int x = 0;
int y = Size.cy - 1;
int c;
int length;
int width = Size.cx;
int height = Size.cy - 1;
BYTE *begin = CompressedBits;
BYTE *bits = CompressedBits;
BYTE *temp;
while (y >= 0)
{
length = *bits++;
if (length)
{
c = *bits++;
while (length--)
{
if (x >= width) break;
temp = UncompressedBits + (((height - y) * Delta) + x);
x++;
*temp = c;
}
}
else
{
length = *bits++;
switch (length)
{
case RLE_EOL:
x = 0;
y--;
break;
case RLE_END:
return;
case RLE_DELTA:
x += *bits++;
y -= *bits++;
break;
default:
while (length--)
{
c = *bits++;
if (x < width)
{
temp = UncompressedBits + (((height - y) * Delta) + x);
x++;
*temp = c;
}
}
if ((bits - begin) & 1)
{
bits++;
}
}
}
}
}