70 lines
2.3 KiB
C
70 lines
2.3 KiB
C
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/*
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* Copyright (C) Microsoft Corporation 1992. All rights reserved.
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*/
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/*
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* aviread.h interface functions to read module providing asynchronous
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* reading of mmio files.
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* Only in WIN32 case.
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*
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* Creating an avird object causes a worker thread to start
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* up and callback to a caller-defined function to read blocks
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* and queue them.
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* The caller can then call avird_getnextbuffer to get each buffer
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* in turn, and once finished with them, should call
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* avird_emptybuffer: this will notify the avird object that
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* the buffer is no longer wanted and can be used to read
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* ahead further blocks.
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*/
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#ifdef _WIN32
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/* handles to avird */
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typedef struct avird_header * HAVIRD;
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/* caller passes us a AVIRD_FUNC pointer to a function that
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* will fill the buffer. It takes four args: the buffer to be filled,
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* a dword instance data (containing the mmio handle or npMCI or whatever),
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* a long giving the
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* size of the block to read, and a pointer to the long where it should
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* return the size of the next block. This function will be never
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* be called out of sequence, so assuming the file pointer is at the
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* correct place before calling avird_startread, blocks will be read
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* in sequence by this function (on the worker thread). The function should
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* return FALSE if the read failed in any way.
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*/
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typedef BOOL (*AVIRD_FUNC)(PBYTE pData, DWORD_PTR dwInstanceData, long lSize, long * plNextSize);
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/*
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* start an avird operation and return a handle to use in subsequent
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* calls. This will cause an asynchronous read (achieved using a separate
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* thread) to start reading the next few buffers. it will not read past
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* nblocks assuming that filler will start at firstblock.
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*/
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HAVIRD avird_startread(AVIRD_FUNC func, DWORD_PTR dwInstanceData, long lFirstSize,
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int firstblock, int nblocks);
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/*
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* return the next buffer from an HAVIRD object. also set plSize to
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* the size of the buffer. Returns NULL if there was an error reading
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* the buffer.
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*/
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PBYTE avird_getnextbuffer(HAVIRD havird, long * plSize);
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/*
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* return a buffer that has been finished with (is now empty)
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*/
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void avird_emptybuffer(HAVIRD havird, PBYTE pBuffer);
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/*
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* delete an avird object. the worker thread will be stopped and all
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* data allocated will be freed. The HAVIRD handle is no longer valid after
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* this call.
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*/
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void avird_endread(HAVIRD havird);
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#endif /* _WIN32 */
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