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Assembler Language Reference

cmp (Compare) Instruction

Purpose

Compares the contents of two general-purpose registers algebraically.

Syntax

Bits Value
0-5 31
6-8 BF
9 /
10 L
11-15 RA
16-20 RB
21-30 0
31 /
cmp BF, L, RA, RB

See Extended Mnemonics of Fixed-Point Compare Instructions for more information.

Description

The cmp instruction compares the contents of general-purpose register (GPR) RA with the contents of GPR RB as signed integers and sets one of the bits in Condition Register Field BF.

BF can be Condition Register Field 0-7; programmers can specify which Condition Register Field will indicate the result of the operation.

The bits of Condition Register Field BF are interpreted as follows:

Bit Name Description
0 LT (RA) < SI
1 GT (RA) > SI
2 EQ (RA) = SI
3 SO SO,OV

The cmp instruction has one syntax form and does not affect the Fixed-Point Exception Register. Condition Register Field 0 is unaffected unless it is specified as BF by the programmer.

Parameters

BF Specifies Condition Register Field 0-7 which indicates result of compare.
L Must be set to 0 for the 32-bit subset architecture.
RA Specifies source general-purpose register for operation.
RB Specifies source general-purpose register for operation.

Examples

The following code compares the contents of GPR 4 and GPR 6 as signed integers and sets Condition Register Field 0 to reflect the result of the operation:

# Assume GPR 4 contains 0xFFFF FFE7.
# Assume GPR 5 contains 0x0000 0011.
# Assume 0 is Condition Register Field 0.
cmp 0,4,6
# The LT bit of Condition Register Field 0 is set. 

Related Information

The cmpi (Compare Immediate) instruction, cmpl (Compare Logical) instruction, cmpli (Compare Logical Immediate) instruction.

Fixed-Point Processor .

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