Avago Technologies LSI53C1010 - Manual (Page 98)

3-58 The SCSI SCRIPTS Processor Instruction Set
3.2.16 RETURN
RETURN [, {IF | WHEN}[NOT][ATN | Phase] [AND | OR] [data[,
AND MASK data]]]
RETURN [, {IF | WHEN}[NOT] CARRY]
Supported by All LSI Logic SCSI SCRIPTS Processors.
Definition SCSI Transfer Control - Return from a Subroutine.
Operands This command has the following operands:
Example RETURN
RETURN WHEN DATA_OUT
WHEN Forces the SCRIPTS engine to wait for a valid SCSI bus phase
before continuing. A valid phase is indicated by assertion of the
SREQ/ signal.
IF Causes the SCRIPTS processor to immediately check for a
valid SCSI bus phase. IF should not be used when comparing
for a phase as this could yield unpredictable results. The only
exception is using a WHEN conditional just prior to the IF
conditional for any given sequence of phase checks.
NOT Negates the comparison. It clears the True bit if present,
otherwise the True bit is set.
Phase Specifies the Message, Command/Data, and Input/Output bit
values that identify the SCSI phase in the instruction. The
desired phase value is compared with the actual values of the
SCSI phase lines before the SCRIPTS processor performs the
instruction. This field is only valid for the initiator mode and
should not be used in the target mode.
ATN Indicates that a return should take place based on the state of
the initiator SATN/ signal. This field is valid only for the target
mode and should not be used in the initiator mode.
data Represents an 8-bit value that is stored in the data field of the
instruction. In addition the Compare Data bit is set.
MASK Represents an 8-bit value that is stored in the mask field of the
instruction. Any bit that is set in the mask causes the
corresponding bit in the data byte to be ignored at the time of
the comparison.
CARRY Indicates that a return should take place based on the value of
the Carry bit in the ALU.