<< Arithmetic | Table of Contents | Input And Output >>
The MIPS architecture is a Load-Store architecture. That is, only the load and store operations can be used to access memory. All other instructions operate on values in a register.
Load Instructions
MIPS provides a number of instructions to load a register. Some load a value from memory, others are used for loading addresses or immediate values.
lb rd, addr- loads a signed byte from the given memory address and stores it in register 'rd'.
lbu rd, addr- loads an unsigned byte from memory.
lh rd, addr- loads a signed halfword from memory.
lhu rd, addr- loads an unsigned halfword from memory.
lw rd, addr- loads a word from the given memory address.
li rd, imm- loads the immediate or literal value into register rd.
la rd, addr- loads the address itself into register rd.
Store Instructions
Likewise, MIPS provides a number of store instructions.
sb rs, addr- stores the low-order byte in register rs to the given memory address.
sh rs, addr- stores the low-order halfword from register rs into memory.
-
sw rs, addr - stores the word from register rs into memory.
-
move rd, rs - copies the contents from register rs into register rd.
Address Format
The base machine uses a single addressing mode or method. Though, the
virtual machine provides several additional formats. Thus, when
referring to a memory address in a load or store instruction, you can
use any of the following
| Format
| Description
| Example
|
(rs)
| get address from register rs
| lw $s0, ($t0)
|
imm
| the immediate value is the address
| lw $s0, 50
|
imm(rs)
| immediate value plus value in register rs
| lw $s0, 50($t0)
|
label
| address of the label.
| lw $s0, x
|
label + imm
| address of the label +/- immediate value.
| lw $s0, x+5
|
label + imm(rs)
| address of the label +/- (immediate value + register rs)
| lw $s0, x+5($t0)
|
<< Arithmetic | Table of Contents | Input And Output >>
