User`s manual

SIOP Firmware Structures
B-14 Single Board Computers SCSI Software UserÕs Manual
B
Data Pointer or Scatter/Gather List Pointer
This field may be modified by the Firmware.
initiator mode
The data pointer field contains a pointer to a buffer where data is transferred
to/from. If the S/G bit is set in the command control field then this field
contains a pointer to a scatter/gather list. The scatter/gather list must be
aligned on a four-byte boundary (longword boundary for the CISC
MVME167; word boundary for the RISC MVME187).
Link Pointer
initiator mode
The link pointer field is initialized by the user for linked commands. This field
points to the command structure which contains the linked CDB. The LINK
bit in the command control field in this structure must be set and the link bit
in the CDB must be set.
Status Return Function Pointer
initiator mode
This field contains the starting address of a function that processes a returned
command structure. The Firmware calls this routine as a "C" function and
passes the address of the finished command structure to it.
void (* ret_stat)(); /* define ret_stat as a pointer to a function */
ret_stat = siop_struc->ret_stat; /* init ret_stat with address of rtn */
ret_stat(&siop_struc); /* call routine with command structure as input */