Encoding:

Format:

DADDI rt, rs, immediate

Purpose:

Doubleword Add Immediate

To add a constant to a 64-bit integer. If overflow occurs, then trap.

Description:

 GPR[rt] = GPR[rs] + immediate

The 16-bit signed immediate is added to the 64-bit value in GPR rs to produce a 64-bit result. If the addition results in

64-bit 2's complement arithmetic overflow, then the destination register is not modified and an Integer Overflow exception occurs. If it does not overflow, the 64-bit result is placed into GPR rt.

Restrictions:

Availability and Compatibility:

This instruction has been removed in Release 6.

The encoding is reused for other instructions introduced by Release 6.

Operation:

temp = (GPR[rs]63||GPR[rs]) + sign_extend(immediate)
if (temp64 != temp63) then
   SignalException(IntegerOverflow)
else
   GPR[rt] = temp63..0
endif

Exceptions:

Integer Overflow, Reserved Instruction

Programming Notes:

DADDIU performs the same arithmetic operation but does not trap on overflow.