MPC555
/
MPC556
CENTRAL PROCESSING UNIT
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
3-28
3.10 Instruction Set
All PowerPC instructions are encoded as single words (32 bits). Instruction formats are
consistent among all instruction types, permitting efficient decoding to occur in parallel
with operand accesses. This fixed instruction length and consistent format greatly sim-
plifies instruction pipelining.
The PowerPC instructions are divided into the following categories:
• Integer instructions include computational and logical instructions.
— Integer arithmetic instructions
— Integer compare instructions
— Integer logical instructions
— Integer rotate and shift instructions
• Floating-point instructions include floating-point computational instructions, as
well as instructions that affect the floating-point status and control register (FP-
SCR).
— Floating-point arithmetic instructions
— Floating-point multiply/add instructions
— Floating-point rounding and conversion instructions
— Floating-point compare instructions
— Floating-point status and control instructions
• Load/store instructions include integer and floating-point load and store instruc-
tions.
— Integer load and store instructions
— Integer load and store multiple instructions
— Floating-point load and store
— Primitives used to construct atomic memory operations (
lwarx
and
stwcx.
in-
structions)
• Flow control instructions include branching instructions, condition register logical
instructions, trap instructions, and other instructions that affect the instruction
flow.
— Branch and trap instructions
— Condition register logical instructions
• Processor control instructions are used for synchronizing memory accesses.
— Move to/from SPR instructions
— Move to/from MSR
— Synchronize
— Instruction synchronize
Note that this grouping of the instructions does not indicate which execution unit exe-
cutes a particular instruction or group of instructions.
Integer instructions operate on byte, half-word, and word operands. Floating-point in-
structions operate on single-precision (one word) and double-precision (one double
word) floating-point operands. The PowerPC architecture uses instructions that are
four bytes long and word-aligned. It provides for byte, half-word, and word operand
loads and stores between memory and a set of 32 GPRs.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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