|
POOL16E 011011 |
rd |
Immediate |
1 |
|
6 |
3 |
6 |
1 |
ADDIUR1SP rd, decoded_immediate_value |
microMIPS |
Add Immediate Unsigned Word One Register (16-bit instr size) |
Add Immediate Unsigned Word One Register (16-bit instr size)
To add a constant to a 32-bit integer.
GPR[rd] = GPR[29] + zero_extend(immediate << 2)
The 6-bit immediate field is first shifted left by two bits and then zero-extended. This amount is added to the 32-bit value in GPR 29 and the 32-bit arithmetic result is sign-extended and placed into GPR rd.
No Integer Overflow exception occurs under any circumstances.
The 3-bit register fields can only specify GPRs $2-$7, $16, $17.
If GPR rs does not contain a sign-extended 32-bit value (bits 63..31 equal), then the result of the operation is
UNPREDICTABLE.
if NotWordValue(GPR[rs]) then UNPREDICTABLE endif temp = GPR[29] + zero_extend(immediate || 02) GPR[rd] = sign_extend(temp31..0)
None
The term "unsigned" in the instruction name is a misnomer; this operation is 32-bit modulo arithmetic that does not trap on overflow. This instruction is appropriate for unsigned arithmetic, such as address arithmetic, or integer arithmetic environments that ignore overflow, such as C language arithmetic.