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 | / |
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:
Item | Description | |
---|---|---|
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
Item | Description |
---|---|
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.