Avago Technologies LSI53C1010 - Manual (Page 60)

3-20 The SCSI SCRIPTS Processor Instruction Set
Description The SCSI Interrupt instruction causes the chip to conditionally halt
execution and post an interrupt request to the external processor. It is
used if the SCSI phase, data, or attention condition compares true with
the phase, data, or attention condition described in the instruction. The
NOT qualifier determines a boolean true/false outcome for the
comparison. If the comparison is false, the SCRIPTS processor does not
post the interrupt but fetches the next instruction in line and continues
execution.
When the optional data field is used, it is compared to the first byte of
the SFBR. This contains the most recent byte of any kind of data that
has been moved into the SFBR register. The user's SCSI SCRIPTS
program determines which routine to execute next based on actual data
values received. Using a series of these compares, the algorithm
processes complex sequences without external processor intervention.
When the optional MASK keyword and its associated value are specified
the SCRIPTS processor selectively compares bits within the data byte.
Figure 3.2 illustrates this comparison. During the comparison, any bits
set in the mask byte cause the corresponding bit in the data byte to be
ignored for the comparison.
Wait Wait for valid phase. Set by the WHEN operand, cleared by the IF
operand.
0 - Perform comparison immediately
1 - Wait for valid phase (SREQ/ asserted by target)
Mask An 8-bit field that masks the value in SFBR before the comparison
with the data field in the instruction takes place. As a result of this
operation, any bits that are set will cause the corresponding bit in
the data byte to be ignored. If this field is not specified, a mask of
0x00 is used.
Data An 8-bit field that is compared with the incoming data after the
mask operation of the mask byte takes place. Comparison
indicates either an equal or not equal condition. If the Data field is
not specified, the compare data bit is cleared and 0x00 is coded
for both the mask and data bytes.
Int_Value A 32-bit user defined value that is available to the external
processor to identify the cause of the interrupt. If the interrupt
conditions are met, the int_value will be available in the DSPS
register for the processor to use to determine the cause of the
interrupt.