150 lines
3.3 KiB
C
150 lines
3.3 KiB
C
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#include <mytypes.h>
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#include <misclib.h>
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#include <dos.h>
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#include <string.h>
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#define BIT16
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#include "mrcicode.h"
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unsigned
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CompressData(
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IN CompressionType Type,
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IN FPBYTE Data,
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IN unsigned DataSize,
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OUT FPBYTE CompressedData,
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IN unsigned BufferSize
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)
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{
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unsigned u;
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switch(Type) {
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case CompressNone:
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default:
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//
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// Force caller to do something intelligent, such as
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// writing directly out of the uncompressed buffer.
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// This avoids an extra memory move.
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//
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u = (unsigned)(-1);
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break;
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case CompressMrci1:
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u = Mrci1MaxCompress(Data,DataSize,CompressedData,BufferSize);
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break;
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case CompressMrci2:
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u = Mrci2MaxCompress(Data,DataSize,CompressedData,BufferSize);
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break;
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}
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return(u);
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}
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unsigned
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DecompressData(
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IN CompressionType Type,
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IN FPBYTE CompressedData,
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IN unsigned CompressedDataSize,
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OUT FPBYTE DecompressedData,
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IN unsigned BufferSize
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)
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{
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unsigned u;
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switch(Type) {
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case CompressNone:
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if(BufferSize >= CompressedDataSize) {
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memmove(DecompressedData,CompressedData,CompressedDataSize);
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u = CompressedDataSize;
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} else {
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u = (unsigned)(-1);
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}
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break;
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case CompressMrci1:
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u = Mrci1Decompress(CompressedData,CompressedDataSize,DecompressedData,BufferSize);
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break;
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case CompressMrci2:
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u = Mrci2Decompress(CompressedData,CompressedDataSize,DecompressedData,BufferSize);
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break;
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default:
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u = (unsigned)(-1);
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break;
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}
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return(u);
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}
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BOOL
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CompressAndSave(
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IN CompressionType Type,
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IN FPBYTE Data,
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IN unsigned DataSize,
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OUT FPBYTE CompressScratchBuffer,
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IN unsigned BufferSize,
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IN UINT FileHandle
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)
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{
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unsigned u;
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unsigned Size;
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unsigned Written;
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FPBYTE p;
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//
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// Need high bit for private use so max data size is 32K.
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// Also disallow 0.
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//
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if(!DataSize || (DataSize > 32768)) {
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return(FALSE);
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}
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//
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// Compress the data.
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//
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u = CompressData(Type,Data,DataSize,CompressScratchBuffer,BufferSize);
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if((u == (unsigned)(-1)) || ((u + sizeof(unsigned)) >= DataSize)) {
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//
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// Data expanded or didn't compress enough to make it
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// worthwhile to store it in compressed form.
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//
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// Store the data size minus 1 with the high bit set to indicate
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// that the data is not compressed.
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//
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Size = DataSize;
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u = (DataSize - 1) | 0x8000;
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p = Data;
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} else {
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//
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// Data has compressed nicely. Store the data size minus 1.
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//
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Size = u;
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u = u-1;
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p = CompressScratchBuffer;
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}
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//
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// Write the header to the file, unless compression type is none.
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//
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if(Type != CompressNone) {
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if(_dos_write(FileHandle,&u,sizeof(unsigned),&Written) || (Written != sizeof(unsigned))) {
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return(FALSE);
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}
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}
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//
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// Write the data to the file.
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//
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if(_dos_write(FileHandle,p,Size,&Written) || (Written != Size)) {
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return(FALSE);
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}
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return(TRUE);
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}
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