Encoding:

EXTEND

11110

offset 10:5

offset 15:11

SWSP

11010

rx

0

000

offset 4:0

5

6

5

5

3

3

5

Format: 

SW rx, offset(sp)

MIPS16e

Store Word (SP-Relative)

Purpose:

Store Word

rx

(SP-Relative, Extended)

To store an SP-relative word to memory.

Description: 

memory[GPR[sp] + offset] = GPR[rx]

The 16-bit offsetis sign-extended and then added to the contents of GPR 29 to form the effective address. The contents of GPR rx are stored at the effective address.

Restrictions:

The effective address must be naturally-aligned. If either of the two least-significan bits of the address is non-zero, an

Address Error exception occurs.

Operation: 

vAddr = sign_extend(offset) + GPR[29]
if vAddr1..0 != 02 then
   SignalException(AddressError)
endif
(pAddr, CCA) = AddressTranslation (vAddr, DATA, STORE)
dataword = GPR[Xlat(rx)]
StoreMemory (CCA, WORD, dataword, pAddr, vAddr, DATA)

Exceptions:

TLB Refill, TLB I valid, TLB Modified, Bus Erro , Address Error