Encoding:

EXTEND

11110

offset 10:5

offset 15:11

LW

10011

rx

ry

offset 4:0

5

6

5

5

3

3

5

Format: 

LW ry, offset(rx)

MIPS16e

Load Word (Extended)

Purpose:

Load Word (Extended)

To load a word from memory as a signed value.

Description: 

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

The 16-bit offsetis sign-extended and then added to the contents of GPR rx to form the effective address. The contents of the word at the memory location specified by the e fective address are loaded into GPR ry.

Restrictions:

The effective address must be naturally-aligned. If either of the 2 least-significanbits of the address is non-zero, an

Address Error exception occurs.

Operation: 

vAddr = sign_extend(offset) + GPR[Xlat(rx)]
if vAddr1..0 != 02 then
   SignalException(AddressError)
endif
(pAddr, CCA) = AddressTranslation (vAddr, DATA, LOAD)
memword = LoadMemory (CCA, WORD, pAddr, vAddr, DATA)
GPR[Xlat(ry)] = memword

Exceptions:

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