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AIX Version 4.3 Assembler Language Reference

tw or t (Trap Word) Instruction

Purpose

Generates a program interrupt when a specified condition is true.

Syntax

PowerPC
tw TO,RA,RB
POWER
t TO,RA,RB

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

Description

The tw and t instructions compare the contents of general-purpose register (GPR) RA with the contents of GPR RB, AND the compared results with TO, and generate a trap-type Program Interrupt if the result is not 0.

The TO bit conditions are defined as follows.

TO bit ANDed with Condition
0 Compares Less Than.
1 Compares Greater Than.
2 Compares Equal.
3 Compares Logically Less Than.
4 Compares Logically Greater Than.

The tw and t instructions have one syntax form and do not affect the Fixed-Point Exception Register or Condition Register Field 0.

Parameters

TO Specifies TO bits that are ANDed with compare results.
RA Specifies source general-purpose register for compare.
RB Specifies source general-purpose register for compare.

Examples

The following code generates a Program Interrupt:

# Assume GPR 4 contains 0x9000 3000.
# Assume GPR 7 contains 0x789A 789B.
tw 0x10,4,7
# A trap type Program Interrupt occurs.

Related Information

Branch Processor.

Fixed-Point Trap Instructions.


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