Specifications

System Macros Invoked by Drivers
SPI$UNMAP_BUFFER
SPI$UNMAP_BUFFER
Releases port mapping resources and deallocates port DMA buffer space, as
required to unmap a process buffer.
Format
SPI$UNMAP_BUFFER
Description
The SPI$UNMAP_BUFFER macro releases mapping resources and deallocates
port DMA buffer space, as required to unmap a process buffer.
Inputs to the SPI$UNMAP_BUFFER macro include the following:
Location Contents
R4 Address of the SPDT.
R5 Address of the SCDRP. The class driver must provide values
in the following fields:
SCDRP$W_NUMREG Number of port DMA buffer pages
allocated
SCDRP$W_MAPREG Page number of the first port DMA
buffer page
The port driver returns the following values to the class driver, preserving R3,
R4, and R5:
Location Contents
R0 SS$_NORMAL.
R5 Address of the SCDRP. The port driver clears SCDRP$W_
NUMREG and SCDRP$W_MAPREG.
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