dmBuffer(3dm)							 dmBuffer(3dm)

NAME    [Toc]    [Back]

     dmBufferMapData - map DMbuffer memory

SYNOPSIS    [Toc]    [Back]

     #include <dmedia/dm_buffer.h>

     void* dmBufferMapData(DMbuffer buffer);

DESCRIPTION    [Toc]    [Back]

     dmBufferMapData returns a pointer to the memory in	buffer.	 The pointer
     can be used for reading and writing the contents of the buffer.  The
     pointer remains valid until the buffer is freed with dmBufferFree(3dm).

     After allocating a	digital	media buffer with dmBufferAllocate(3dm), the
     pointer returned dmBufferMapData by can be	used to	write data into	the
     buffer.  However, once the	buffer has been	sent to	one of the digital
     media libraries, the pointer may be used to read from the buffer, but the
     contents of the buffer should not be modified.  This is because the
     libraries may retain a reference to the buffer indefinitely. The
     functions that send buffers are:  dmICSend(3dm), vlDMBufferPutValid(3dm),
     and glXAssociateDMPbufferSGIX(3G).

     The contents of a buffer should only be modified when it is newly
     allocated by dmBufferAllocate(3dm).  Buffers received from	the the	video
     library (with vlDMBufferGetValid(3dm)) or the image conversion library
     (dmICReceive(3dm))	should not be modified.

     The number	of bytes of valid data is available from dmBufferGetSize(3dm).

     WARNING: A	single DMbuffer	should not be used with	both
     glXAssociateDMPbufferSGIX and dmBufferMapData.  Cache coherency is	not
     guaranteed	if a DMbuffer that has been rendered into is mapped, or	if a
     mapped buffer is rendered into.

SEE ALSO    [Toc]    [Back]

     dmBufferGetSize(3dm), dmBufferAllocate(3dm), dmICReceive(3dm),
     dmICSend(3dm), vlDMBufferGetValid(3dm), vlDMBufferPutValid(3dm).


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