Source code of Windows XP (NT5)
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/*
* Copyright (C) Microsoft Corporation 1992. All rights reserved. */
/*
* aviread.h interface functions to read module providing asynchronous * reading of mmio files. * Only in WIN32 case. * * Creating an avird object causes a worker thread to start * up and callback to a caller-defined function to read blocks * and queue them. * The caller can then call avird_getnextbuffer to get each buffer * in turn, and once finished with them, should call * avird_emptybuffer: this will notify the avird object that * the buffer is no longer wanted and can be used to read * ahead further blocks. */
#ifdef _WIN32
/* handles to avird */typedef struct avird_header * HAVIRD;
/* caller passes us a AVIRD_FUNC pointer to a function that
* will fill the buffer. It takes four args: the buffer to be filled, * a dword instance data (containing the mmio handle or npMCI or whatever), * a long giving the * size of the block to read, and a pointer to the long where it should * return the size of the next block. This function will be never * be called out of sequence, so assuming the file pointer is at the * correct place before calling avird_startread, blocks will be read * in sequence by this function (on the worker thread). The function should * return FALSE if the read failed in any way. */typedef BOOL (*AVIRD_FUNC)(PBYTE pData, DWORD_PTR dwInstanceData, long lSize, long * plNextSize);
/*
* start an avird operation and return a handle to use in subsequent * calls. This will cause an asynchronous read (achieved using a separate * thread) to start reading the next few buffers. it will not read past * nblocks assuming that filler will start at firstblock. */HAVIRD avird_startread(AVIRD_FUNC func, DWORD_PTR dwInstanceData, long lFirstSize, int firstblock, int nblocks);
/*
* return the next buffer from an HAVIRD object. also set plSize to * the size of the buffer. Returns NULL if there was an error reading * the buffer. */PBYTE avird_getnextbuffer(HAVIRD havird, long * plSize);
/*
* return a buffer that has been finished with (is now empty) */void avird_emptybuffer(HAVIRD havird, PBYTE pBuffer);
/*
* delete an avird object. the worker thread will be stopped and all * data allocated will be freed. The HAVIRD handle is no longer valid after * this call. */void avird_endread(HAVIRD havird);
#endif /* _WIN32 */
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