Specifications

System Macros Invoked by Drivers
SPI$CONNECT
Table 2–4 lists the port driver return values to the class driver.
Table 2–4 Values Returned by the SPI$CONNECT Macro
Location Contents
R0 Port status. The port driver returns one of the following
values:
SS$_DEVALLOC Connection already open for this
target.
SS$_DEVOFFLINE Port is off line and allows no
connections.
SS$_INSFMEM Insufficient memory to allocate
SCDT.
SS$_NORMAL Connection formed.
SS$_NOSUCHDEV Port not found.
R1 Maximum byte count allowed (SPDT$L_MAXBYTECNT) for a
data transfer.
R2 Address of the SCDT.
R3 Port capability mask of SPDT$L_PORT_FLAGS. The
following bits are defined by the $SPDTDEF macro (in
SYS$LIBRARY:LIB.MLB):
SPDT$M_SYNCH Supports synchronous mode.
SPDT$M_ASYNCH Supports asynchronous mode.
SPDT$M_MAPPING_REG Supports map registers.
SPDT$M_BUF_DMA Supports buffered DMA.
SPDT$M_DIR_DMA Supports direct DMA.
SPDT$M_AEN Supports asynchronous event
notification.
SPDT$M_LUNS Supports LUNs (logical unit
numbers).
SPDT$M_CMDQ Supports SCSI-2 command
queuing I/O.
Bits <25:31> Contains the recommended byte
count divisor for the class driver
to derive a proper DMA byte
count for the port.
R4 Address of the SPDT.
2–71