Encoding:

POOL32A

000000

rt

rs

sa

0

SRA

0010000000

6

5

5

5

1

10

Format: 

SRA rt, rs, sa

microMIPS

Shift Word Right Arithmetic

Purpose:

Shift Word Right Arithmetic

To execute an arithmetic right-shift of a word by a fixed number of bits.

Description: 

 GPR[rt] = GPR[rs] >> sa   (arithmetic)

The contents of the low-order 32-bit word of GPR rs are shifted right, duplicating the sign-bit (bit 31) in the emptied bits; the word result is sign-extended and placed in GPR rt. The bit-shift amount is specified by sa.

Restrictions:

On 64-bit processors, if GPR rs does not contain a sign-extended 32-bit value (bits 63..31 equal), then the result of the operation is UNPREDICTABLE.

Operation: 

if NotWordValue(GPR[rs]) then 
   UNPREDICTABLE 
endif
s = sa
temp = GPR[rs]31)s || GPR[rs]31..s
GPR[rt] = sign_extend(temp)

Exceptions:

None