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usw

Unaligned store word Pseudo-instruction

Stores the 32 bits of $t1 at any byte address, whether or not the address is word-aligned.

Forms

Operands

$t1
Any general-purpose register, $0 to $31, using its numeric or named spelling, such as $8 or $t0 ($zero is $0; $ra is $31).
imm
An immediate value: a signed 16-bit value (-32768 to 32767) or a 32-bit value (-2147483648 to 4294967295). The assembler chooses a supported encoding for the value and other operands; a pseudoinstruction may expand into several instructions.
$t2
A general-purpose register. It may be the same register as $t1.
imm32
A 32-bit immediate, -2147483648 to 4294967295. Pseudoinstruction expansion may overwrite $at, losing its previous value.
label
A named address in the program, such as the start of a loop or a variable in .data. 
.data
.align 2
data: .word 0
.text
# Write initialized value 0x12345678 with usw; inspect data bytes after the instruction: [0x00, 0x78, 0x56, 0x34, 0x12] at offset 1.
la $t1, data
li $t0, 0x12345678
usw $t0, 1($t1)