IDT
Operation Section Notation and Functions
79RC32355 User Reference Manual
A - 5
November 4, 2002
Notes
Figure A.7 Sample Instruction Operation
Exceptions Field
The Exceptions field lists the exceptions that can be caused by Operation of the instruction. It omits
exceptions that can be caused by the instruction fetch, for instance, TLB Refill, and also omits exceptions
that can be caused by asynchronous external events such as an Interrupt. Although a Bus Error exception
may be caused by the operation of a load or store instruction, this section does not list Bus Error for load
and store instructions because the relationship between load and store instructions and external error indi-
cations, like Bus Error, are dependent upon the implementation.
Figure A.8 Sample Instruction Exception
An instruction may cause implementation-dependent exceptions that are not present in the Exceptions
section.
Programming Notes and Implementation Notes Fields
The Notes sections contain material that is useful for programmers and implementors, respectively, but
that is not necessary to describe the instruction and does not belong in the description sections.
Figure A.9 Sample Instruction Programming Notes
Operation Section Notation and Functions
In an instruction description, the Operation section uses a high-level language notation to describe the
operation performed by each instruction. The contents of the Operation section are described here,
including the special symbols and functions that are used.
Instruction Execution Ordering
Each of the high-level language statements in the Operations section are executed sequentially (except
as constrained by conditional and loop constructs).
Operation:
temp
(GPR[rs]
31
||GPR[rs]
31..0
) + (GPR[rt]
31
||GPR[rt]
31..0
)
if temp32
≠
temp
31
then
SignalException(IntergerOverflow)
else
GPR[rd] temp
endif
Exceptions:
Integer Overflow
Programming Notes:
ADDU performs the same arithmetic operation but does not trap on overflow.