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https://github.com/reactos/reactos.git
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100 lines
2.5 KiB
C
100 lines
2.5 KiB
C
/*
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* COPYRIGHT: See COPYING in the top level directory
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* PROJECT: ReactOS kernel
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* PURPOSE: RLE compression
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* FILE: win32ss/gdi/eng/rlecomp.c
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* PROGRAMER: Jason Filby
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*/
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#include <win32k.h>
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#define NDEBUG
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#include <debug.h>
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enum Rle_EscapeCodes
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{
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RLE_EOL = 0, /* End of line */
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RLE_END = 1, /* End of bitmap */
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RLE_DELTA = 2 /* Delta */
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};
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VOID DecompressBitmap(SIZEL Size, BYTE *CompressedBits, BYTE *UncompressedBits, LONG Delta, ULONG Format, ULONG cjSizeImage)
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{
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INT x = 0;
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INT y = Size.cy - 1;
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INT c;
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INT length;
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INT width;
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INT height = y;
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BYTE *begin = CompressedBits;
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BYTE *bits = CompressedBits;
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BYTE *temp;
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INT shift = 0;
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if ((Format == BMF_4RLE) || (Format == BMF_4BPP))
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shift = 1;
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else if ((Format != BMF_8RLE) && (Format != BMF_8BPP))
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return;
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width = ((Size.cx + shift) >> shift);
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_SEH2_TRY
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{
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while (y >= 0 && (bits - begin) <= cjSizeImage)
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{
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length = (*bits++) >> shift;
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if (length)
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{
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c = *bits++;
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while (length--)
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{
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if (x >= width) break;
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temp = UncompressedBits + (((height - y) * Delta) + x);
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x++;
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*temp = c;
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}
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}
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else
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{
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length = *bits++;
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switch (length)
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{
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case RLE_EOL:
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x = 0;
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y--;
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break;
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case RLE_END:
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_SEH2_YIELD(return);
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case RLE_DELTA:
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x += (*bits++) >> shift;
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y -= (*bits++) >> shift;
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break;
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default:
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length = length >> shift;
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while (length--)
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{
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c = *bits++;
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if (x < width)
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{
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temp = UncompressedBits + (((height - y) * Delta) + x);
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x++;
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*temp = c;
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}
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}
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if ((bits - begin) & 1)
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{
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bits++;
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}
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}
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}
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}
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}
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_SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER)
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{
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DPRINT1("Decoding error\n");
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}
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_SEH2_END;
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return;
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}
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