tw or t (Trap Word) instruction
Purpose
Generates a program interrupt when a specified condition is true.
Syntax
| Bits | Value |
|---|---|
| 0-5 | 31 |
| 6-10 | TO |
| 11-15 | RA |
| 16-20 | RB |
| 21-30 | 4 |
| 31 | / |
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
| 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. |
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.