
MOTOROLA
Chapter 2. Programming Model
2-21
The execution of an
sc
instruction invokes the system call exception handler that
permits a program to request the system to perform a service.
The execution of a trap instruction invokes the program exception trap handler.
The execution of a floating-point instruction when floating-point instructions are
disabled or unavailable invokes the floating-point unavailable exception handler.
The execution of an instruction that causes a floating-point exception while
exceptions are enabled
in the MSR invokes the program exception handler.
Exceptions caused by asynchronous events are described in Chapter 4, “Exceptions.”
2.3.3 Instruction Set Overview
This section provides a brief overview of the PowerPC instructions implemented in the
603e and highlights any special information with respect to how the 603e implements a
particular instruction. Note that the categories used in this section correspond to those used
in Chapter 4, “Addressing Modes and Instruction Set Summary,” in
The Programming
Environments Manual
. These categorizations are somewhat arbitrary and are provided for
the convenience of the programmer and do not necessarily reflect the PowerPC architecture
specification.
Note that some of the instructions have the following optional features:
CR Update—The dot (
.
) suffix on the mnemonic enables the update of the CR.
Overflow option—The
o
suffix indicates that the overflow bit in the XER is enabled.
2.3.4 PowerPC UISA Instructions
The PowerPC UISA includes the base user-level instruction set (excluding a few user-level
cache control, synchronization, and time base instructions), user-level registers,
programming model, data types, and addressing modes. This section discusses the
instructions defined in the UISA.
2.3.4.1 Integer Instructions
This section describes the integer instructions. These consist of the following:
Integer arithmetic instructions
Integer compare instructions
Integer logical instructions
Integer rotate and shift instructions
Integer instructions use the content of the GPRs as source operands and place results into
GPRs, into the XER, and into condition register (CR) fields.