Avago Technologies LSI53C896 User Manual
Page 256
5-28
SCSI SCRIPTS Instruction Set
Version 3.3
Copyright © 1998–2003 by LSI Logic Corporation. All rights reserved.
When the JUMP64 instruction is used, a third Dword is
fetched and loaded into the
register. Bit 22 indicates whether the jump is to a 32-bit
address (0) or a 64-bit address (1). All combinations of
jumps are still valid for JUMP64.
Call Instruction
The LSI53C896 can do a true/false comparison of the
ALU carry bit, or compare the phase and/or data as
defined by the Phase Compare, Data Compare, and
True/False bit fields. If the comparisons are true, it loads
the
register with the
contents of the
DMA SCRIPTS Pointer Save (DSPS)
register, and that address value becomes the address of
the next instruction.
When the LSI53C896 executes a Call instruction, the
instruction pointer contained in the
register is stored in the
register. Because the TEMP register
is not a stack and can only hold one Dword, nested call
instructions are not allowed.
If the comparisons are false, the LSI53C896 fetches the
next instruction from the address pointed to by the
register, and the
instruction pointer is not modified.
Return Instruction
The LSI53C896 can do a true/false comparison of the
ALU carry bit, or compare the phase and/or data as
defined by the Phase Compare, Data Compare, and
True/False bit fields. If the comparisons are true, it loads
the
register with the
contents of the
DMA SCRIPTS Pointer Save (DSPS)
register. That address value becomes the address of the
next instruction.
When a Return instruction is executed, the value stored
in the
register is returned to the
register. The LSI53C896
does not check to see whether the Call instruction has
already been executed. It does not generate an interrupt
if a Return instruction is executed without previously
executing a Call instruction.