MIPS Assembly/Memory Instructions

Load and store instructions use a special syntax:

 instr rt, imm(rs)

The memory address used for the load or store is rs + imm. The immediate is sign-extended.

Load Instructions

Instruction:

lbu

type:

I Type

Loads a byte and does not sign-extend the value.

Instruction:

lhu

type:

I Type

Loads a halfword, or two bytes, and does not sign-extend the value. The halfword must be aligned (i.e., it must start at an even address).

Instruction:

lw

type:

I Type

Loads a word (four-bytes) from memory. The word must be aligned (i.e., the last two bits of the address must be zero).

Store Instructions

Instruction:

sb

type:

I Type

Stores the least significant (rightmost) byte of rt to memory.

Instruction:

sh

type:

I Type

Stores the least significant (rightmost) halfword of rt to memory.

Instruction:

sw

type:

I Type

Stores the contents of rt in memory.