tw or t (Trap Word) instruction


Generates a program interrupt when a specified condition is true.


Bits Value
0-5 31
6-10 TO
11-15 RA
16-20 RB
21-30 4
31 /
tw TO, RA, RB
POWER® family 
t TO, RA, RB


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.


Item Description
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.


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.