93 lines
3.8 KiB
C
93 lines
3.8 KiB
C
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/*
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** buffers.h - Function prototypes and global variables used to manipulate
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** buffers used in I/O and expansion.
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**
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** Author: DavidDi
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*/
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// Constants
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/////////////
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// N.b., rgbyteInBuf[] allocated with one extra byte for UnreadByte().
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#define MAX_IN_BUF_SIZE 32768U // maximum size of input buffer
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#define MAX_OUT_BUF_SIZE 32768U // maximum size of output buffer
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#define IN_BUF_STEP 1024U // decrement sizes used in I/O buffer
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#define OUT_BUF_STEP 1024U // allocation in InitBuffers()
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#define FLUSH_BYTE ((BYTE) 'F') // dummy character used to flush
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// rgbyteOutBuf[] to output file
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#define END_OF_INPUT 500 // ReadInBuf() EOF flag for input file
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// DOS file handle flag indicating that the compression savings should be
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// computed, but no output file written.
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#define NO_DOSH (-2)
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#define READ_IT TRUE // GetIOHandle() bRead flag values
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#define WRITE_IT FALSE
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// Macros
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//////////
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// Read a byte (buffered) from input file. Stores byte read in argument.
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// Returns TRUE if successful, or one of ReadInBuf()'s error codes if
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// unsuccessful.
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//-protect-
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#define ReadByte(byte) ((pLZI->pbyteInBuf < pLZI->pbyteInBufEnd) ? \
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((byte = *pLZI->pbyteInBuf++), TRUE) : \
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ReadInBuf((BYTE ARG_PTR *)&byte, doshSource, pLZI))
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// Put at most one byte back into the buffered input. N.b., may be used at
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// most (pbyteInBuf - &rgbyteInBuf[1]) times. E.g., may be used only once at
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// beginning of buffer. Return value is always TRUE.
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//-protect-
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#define UnreadByte() ((pLZI->pbyteInBuf == &pLZI->rgbyteInBuf[1]) ? \
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(pLZI->bLastUsed = TRUE) : \
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(--pLZI->pbyteInBuf, TRUE))
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// Write a byte (buffered) to output file. Returns TRUE if successful, or
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// one of WriteOutBuf()'s error codes if unsuccessful. ALWAYS increments
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// cblOutSize.
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#define WriteByte(byte) ((pLZI->pbyteOutBuf < pLZI->pbyteOutBufEnd) ? \
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((*pLZI->pbyteOutBuf++ = byte), pLZI->cblOutSize++, TRUE) : \
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(pLZI->cblOutSize++, WriteOutBuf(byte, doshDest, pLZI)))
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// Flush output buffer. DOES NOT increment cblOutSize. N.b., you cannot
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// perform a valid UnreadByte() immediately after FlushOutputBuffer() because
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// the byte kept will be the bogus FLUSH_BYTE.
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#define FlushOutputBuffer(dosh, pLZI) WriteOutBuf(FLUSH_BYTE, dosh, pLZI)
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// Reset buffer pointers to empty buffer state.
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//-protect-
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#define ResetBuffers() { pLZI->pbyteInBufEnd = &pLZI->rgbyteInBuf[1] + pLZI->ucbInBufLen; \
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pLZI->pbyteInBuf = &pLZI->rgbyteInBuf[1] + pLZI->ucbInBufLen; \
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pLZI->bLastUsed = FALSE; \
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pLZI->pbyteOutBufEnd = pLZI->rgbyteOutBuf + pLZI->ucbOutBufLen; \
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pLZI->pbyteOutBuf = pLZI->rgbyteOutBuf; \
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pLZI->cblOutSize = 0L; \
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}
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// The buffer pointers are initialized to NULL to indicate the buffers have
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// not yet been allocated. init.c!InitGlobalBuffers() allocates the buffers
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// and sets the buffers' base pointers. buffers.h!ResetBufferPointers() sets
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// the buffers' current position and end position pointers.
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// Prototypes
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//////////////
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// buffers.c
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extern INT ReadInBuf(BYTE ARG_PTR *pbyte, INT doshSource, PLZINFO pLZI);
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extern INT WriteOutBuf(BYTE byteNext, INT doshDest, PLZINFO pLZI);
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// init.c
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extern PLZINFO InitGlobalBuffers(DWORD dwOutBufSize, DWORD dwRingBufSize, DWORD dwInBufSize);
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extern PLZINFO InitGlobalBuffersEx();
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extern VOID FreeGlobalBuffers(PLZINFO);
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extern INT GetIOHandle(CHAR ARG_PTR *pszFileName, BOOL bRead, INT ARG_PTR *pdosh,
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LONG *pcblInSize);
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