windows-nt/Source/XPSP1/NT/multimedia/media/avi/mciavi32/aviread.h
2020-09-26 16:20:57 +08:00

70 lines
2.3 KiB
C

/*
* 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 The HAVIRD handle is no longer valid after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 */