
MOTOROLA
Chapter 3. Instruction Set Model
3-25
Instruction Set Summary
3.2.4.3.10 Floating-Point Store Instructions
There are three basic forms of the store instruction—single-precision, double-precision,
and integer. The integer form is supported by the optional
stfiwx
instruction. Because the
FPRs support only double-precision format for floating-point data, the FPU converts
double-precision data to single-precision format before storing the operands. The
conversion steps are described in “Floating-Point Store Instructions” in Appendix D,
“Floating-Point Models,” in the
Programming Environments Manual
.
Implementation Note
—The PowerPC architecture defines store with update instructions
with
r
A = 0 as an invalid form; however, the core treats this case as valid.
Table 3-20 lists the floating-point store instructions.
3.2.4.4
Branch and Flow Control Instructions
Branch instructions are executed by the branch processing unit (BPU). The BPU receives
branch instructions from the fetch unit and performs CR lookahead operations on
conditional branches to resolve them early, achieving the effect of a zero-cycle branch in
many cases.
Load Floating-Point Single
lfs
fr
D
,
d(
r
A)
Load Floating-Point Single Indexed
lfsx
fr
D
,r
A
,r
B
Load Floating-Point Single with Update
lfsu
fr
D
,
d(
r
A)
Load Floating-Point Single with Update
Indexed
lfsux
fr
D
,r
A
,r
B
Table 3-20. Floating-Point Store Instructions
Name
Mnemonic
Operand Syntax
Store Floating-Point as Integer Word Indexed
stfiwx
fr
S
,r
A
,r
B
Store Floating-Point Double
stfd
fr
S
,
d(
r
A)
Store Floating-Point Double Indexed
stfdx
fr
S
,r
A
,r
B
Store Floating-Point Double with Update
stfdu
fr
S
,
d(
r
A)
Store Floating-Point Double with Update
Indexed
stfdux
fr
S
,r
A
,r
B
Store Floating-Point Single
stfs
fr
S
,
d(
r
A)
Store Floating-Point Single Indexed
stfsx
fr
S
,r
A
,r
B
Store Floating-Point Single with Update
stfsu
fr
S
,
d(
r
A)
Store Floating-Point Single with Update
Indexed
stfsux
fr
S
,r
A
,r
B
Table 3-19. Floating-Point Load Instructions (continued)
Name
Mnemonic
Operand Syntax
F
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n
.