AN2203 Freescale Semiconductor / Motorola, AN2203 Datasheet - Page 59

• Manufacturer Part Number: AN2203
• Description: MPC7450 RISC Microprocessor Family Software Optimization Guide
• Manufacturer: Freescale Semiconductor / Motorola

MOTOROLA
les0+
r = ((signed_word) v0 <= 0) + v1
ges0+
r = ((signed_word) v0 >= 0) + v1
lts0+
r = ((signed_word) v0 < 0) + v1
gts0+
r = ((signed_word) v0 > 0) + v1
MPC7450 RISC Microprocessor Family Software Optimization Guide
Operation
Table 5-4. Comparisons with Addition (continued)
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subfic r5,r3,0
srwi r6,r3,31
adde r7,r6,r4
Cycles: 4
addi r5,r4,1
srwi r6,r3,31
subf r7,r6,r5
Cycles: 2
srwi r5,r3,31
add r6,r5,r4
Cycles: 2
neg r5,r3
srawi r6,r5,31
addze r7,r4
Cycles: 6
Compiler Writer’s
Guide Code
cntlzw r6,r3
li r5,1
srw r7,r5,r6
add r8,r7,r4
Cycles: 3
srwi r6,r3,31
addi r5,r4,1
subf r7,r6,r5
Cycles: 2
neg r5,r3
andc r6,r5,r3
srwi r7,r6,31
add r8,r7,r4
Cycles: 4
MPC7450 Code
(If Different)
Comparisons with Addition
The MPC7450
sequence
simply
reorders the
first 2
instructions.
This is likely to
result in better
performance
on future
processors.
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