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AIX Version 4.3 Assembler Language Reference

twi or ti (Trap Word Immediate) Instruction


Generates a program interrupt when a specified condition is true.


twi TO,RA,SI

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


The twi and ti instructions compare the contents of general-purpose register (GPR) RA with the sign extended SI field, 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 twi and ti instructions have one syntax form and do not affect the Fixed-Point Exception Register or Condition Register Field 0.


TO Specifies TO bits that are ANDed with compare results.
RA Specifies source general-purpose register for compare.
SI Specifies sign-extended value for compare.


The following code generates a Program Interrupt:

# Assume GPR 4 holds 0x0000 0010.
twi 0x4,4,0x10
# A trap type Program Interrupt occurs.

Related Information

Branch Processor.

Fixed-Point Trap Instructions.

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