Gone is the one… the autumn coat is folded

Still hiding a bit of golden sunlight in the flap

My sorrow growing on branches as leaves

Not fall off quickly but wait for another autumn

Hello everyone, it’s me again, an amateur entering the field. Lately, due to being swamped with company projects, I haven’t had the time to explore and write blog anymore ☹. But today, on the occasion of a leisurely day, just like my single status during the winter season – I take some time to continue this ongoing series, hoping you’ll continue reading?).

Arithmetic Computational Instructions.

Addition Instruction.

As far as I know, it includes:

Instruction	Example		Meaning
add	add $1,$2,$3	$1=$2+$3
add immediate	addi $1,$2,100	$1=$2+100	It means addition with constant numbers
add unsigned	addu $1,$2,$3	$1=$2+$3	Unsigned integer addition,
add immediate unsigned	addiu $1,$2,100	$1=$2+100	Unsigned integer addition,

Syntax:

For add, addu: <instruction name> <destination register>, <source register 1>, <source register 2>

For addi, addiu: <instruction name> <destination register>, <source register 1>, <constant number>

Specific example:

Compiling the above .c file with the MIPS architecture as follows:

mips-linux-gnu-gcc -O3 -S -mfp32 -march=mips32 Sum.c

Image when compiled to MIPS Assembly.

Why do I declare a signed int, but the assembly output uses addiu? From what I’ve briefly researched online, most compilers tend to use addu and addiu to avoid “overflow” traps. The add and addi instructions seem to be used only when manually coding or in ISAs like x86, ARM…

Subtraction Instruction.

Instruction	Example		Meaning
subtract	sub $1,$2,$3	$1=$2-$3
subtract unsigned	subu $1,$2,$3	$1=$2-$3	Unsigned integer subtraction

Syntax:

sub,subu: <instruction name > <destination register> , <register 1>, < register 2>

Specific example:

Image when compiled to MIPS Assembly.

Multiplication Instruction.

Instruction

Example

Meaning

Multiply (withoutoverflow)

mul $1,$2,$3

$1=$2*$3

Result fits in 32 bits.

Multiply

mult $2,$3

$hi,$low=$2*$3

High 32-bit overflow multiplication saved in hi register

– Low 32 bits stored in low register.

Specific example:

Division Instruction

Lệnh

Ví dụ

Ý nghĩa

Divide

div $2,$3

$hi,$low=$2/$3

Kết quả được lưu trong thanh ghi hi

Thươn số được lưu trong thanh ghi low

Alright, I’m too lazy to capture images for this part 😄. This is similar to the previous images anyway.

Logic Computational Instructions.

Instruction	Example		Meaning
and	and $1,$2,$3	$1=$2&$3	Bitwise AND
or	or $1,$2,$3	$1=$2\|$3	Bitwise OR
xor	xor $1,$2,$3	$1 = $2 ??$3	Bitwise XOR
nor	nor $1,$2,$3	$1 = ~($2 \| $3) not of OR	Bitwise NOR
and immediate	andi $1,$2,100	$1=$2&100	Bitwise AND register, constant number
or immediate	or $1,$2,100	$1=$2\|100	Bitwise OR register, constant number
xor immediate	xori $1, $2,10	$1 = ~$2 &~10	Bitwise XOR register, constant number
shift left logical	sll $1,$2,10	$1=$2<<10	Left shift
shift right logical	srl $1,$2,10	$1=$2>>10	Right shift