2.3 Supported Instructions

Not supported item is displayed as red characters.
Unaligned load and store operations (LWL,SWL,LWR,SWR) are not supported.

ADD -- Add

Description: Adds two registers and stores the result in a register(Exception by Overflow)
Operation: $d = $s + $t;
Syntax: add $d, $s, $t
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O 5bit 5bit 5bit 5bit 6'b100_000

ADDI -- Add immediate

Description: Adds a register and a signed immediate value and stores the result in a register
Operation: $t = $s + imm;
Syntax: addi $t, $s, imm
Encoding:
OPCODE Source Target Immediate
6'b001000 5bit 5bit 16bit

ADDIU -- Add immediate unsigned

Description: Adds a register and an unsigned immediate value and stores the result in a register
Operation: $t = $s + imm;
Syntax: addiu $t, $s, imm
Encoding:
OPCODE Source Target Immediate
6'b001001 5bit 5bit 16bit

ADDU -- Add unsigned

Description: Adds two registers and stores the result in a register
Operation: $d = $s + $t;
Syntax: addu $d, $s, $t
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O 5bit 5bit 5bit 5'h0 6'b100_001

AND -- Bitwise and

Description: Bitwise ands two registers and stores the result in a register
Operation: $d = $s & $t;
Syntax: and $d, $s, $t
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O 5bit 5bit 5bit 5'h0 6'b100100

ANDI -- Bitwise and immediate

Description: Bitwise ands a register and an immediate value and stores the result in a register
Operation: $t = $s & imm;
Syntax: andi $t, $s, imm
Encoding:
OPCODE Source Target Immediate
6'b001100 5bit 5bit 16bit

BEQ -- Branch on equal

Description: Branches if the two registers are equal
Operation: if $s == $t PC +=imm << 2;
Syntax: beq $s, $t, imm
Encoding:
OPCODE Source Target Immediate
6'b000100 5bit 5'h0 16bit

BGEZ -- Branch on greater than or equal to zero

Description: Branches if the register is greater than or equal to zero
Operation: if $s >= 0 PC +=offset << 2;
Syntax: bgez $s, offset
Encoding:
OPCODE Source Target Immediate
6'b000001 5bit 5'b00001 16bit

BGEZAL -- Branch on greater than or equal to zero and link

Description: Branches if the register is greater than or equal to zero and saves the return address in $31
Operation: if $s >= 0 $31 = PC + 8 ; PC +=imm << 2;
Syntax: bgezal $s, imm
Encoding:
OPCODE Source Target Immediate
6'b000001 5bit 5'h10001 16bit

BGTZ -- Branch on greater than zero

Description: Branches if the register is greater than zero
Operation: if $s > 0 PC +=imm << 2;
Syntax: bgtz $s, imm
Encoding:
OPCODE Source Target Immediate
6'b000111 5bit 5'h0 16bit

BLEZ -- Branch on less than or equal to zero

Description: Branches if the register is less than or equal to zero
Operation: if $s <= 0 PC +=imm << 2;
Syntax: blez $s, imm
Encoding:
OPCODE Source Target Immediate
6'b000110 5bit 5'h0 16bit

BLTZ -- Branch on less than zero

Description: Branches if the register is less than zero
Operation: if $s < 0 PC+=imm << 2;
Syntax: bltz $s, imm
Encoding:
OPCODE Source Target Immediate
6'b00001 5bit 5'b00000 16bit

BLTZAL -- Branch on less than zero and link

Description: Branches if the register is less than zero and saves the return address in $31
Operation: if $s < 0 $31 = PC + 8 ; PC+=imm << 2;
Syntax: bltzal $s, imm
Encoding:
OPCODE Source Target Immediate
6'b000001 5bit 5'b10000 16bit

BNE -- Branch on not equal

Description: Branches if the two registers are not equal
Operation: if $s != $t PC+=imm << 2;
Syntax: bne $s, $t, imm
Encoding:
OPCODE Source Target Immediate
6'b000101 5bit 5'h0 16bit

Break -- Break

Description: Generates break point.
Operation:
Syntax: break
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O ????? ????? ????? ????? 6'b001101



DIV -- Divide

Description: Divides $s by $t and stores the quotient in $LO and the remainder in $HI
Operation: $LO = $s / $t; $HI = $s % $t;
Syntax: div $s, $t
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O 5bit 5bit 5'h0 5'h0 6'b011010

DIVU -- Divide unsigned

Description: Divides $s by $t and stores the quotient in $LO and the remainder in $HI
Operation: $LO = $s / $t; $HI = $s % $t;
Syntax: divu $s, $t
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O 5bit 5bit 5'h0 5'h0 6'b011011

J -- Jump

Description: Jumps to the calculated address
Operation: PC = nPC; nPC = (PC & 0xf0000000) | (imm26 << 2);
Syntax: j imm26
Encoding:
OPCODE Immediate
6'b000010 26bit

JAL -- Jump and link

Description: Jumps to the calculated address and stores the return address in $31
Operation: $31 = PC + 8 ; PC = nPC; nPC = (PC & 0xf0000000) | (imm26 << 2);
Syntax: jal imm26
Encoding:
OPCODE Immediate
6'b000011 26bit

JALR -- Jump and link Register

Description: Jump to the address contained in register $s and stores the return address in $d
Operation: $d = PC + 8 ; PC = $s
Syntax: jalr $d,$s
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O 5bit 5'h0 5bit 5'h0 6'b001001

JR -- Jump register

Description: Jump to the address contained in register $s
Operation: PC = nPC; nPC = $s;
Syntax: jr $s
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O 5bit 5'h0 5'h0 5'h0 6'b001000

LB -- Load byte

Description: A signed extented byte is loaded into a register from the specified address.
Operation: $t = MEM[$s + imm]; ;
Syntax: lb $t, imm($s)
Encoding:
OPCODE Source Target Immediate
6'b100000 5bit 5bit 16bit

LBU -- Load byte unsigned

Description: A unsigned extented byte is loaded into a register from the specified address.
Operation: $t = MEM[$s + imm]; ;
Syntax: lbu $t, imm($s)
Encoding:
OPCODE Source Target Immediate
6'b100100 5bit 5bit 16bit


LH -- Load Half

Description: A signed extented half word is loaded into a register from the specified address.
Operation: $t = MEM[$s + imm]; ;
Syntax: lh $t, imm($s)
Encoding:
OPCODE Source Target Immediate
6'b100001 5bit 5bit 16bit


LHU -- Load Half unsigned

Description: A byte is loaded into a register from the specified address.
Operation: $t = MEM[$s + imm]; ;
Syntax: lhu $t, imm($s)
Encoding:
OPCODE Source Target Immediate
6'b100101 5bit 5bit 16bit


LUI -- Load upper immediate

Description: The immediate value is shifted left 16 bits and stored in the register. The lower 16 bits are zeroes.
Operation: $t = (imm << 16);
Syntax: lui $t, imm
Encoding:
OPCODE Source Target Immediate
6'b001111 ????? 5bit 16bit

LW -- Load word

Description: A word is loaded into a register from the specified address.
Operation: $t = MEM[$s + imm];
Syntax: lw $t, imm($s)
Encoding:
OPCODE Source Target Immediate
6'b100011 5bit 5bit 16bit

MFHI -- Move from HI

Description: The contents of register HI are moved to the specified register.
Operation: $d = $HI;
Syntax: mfhi $d
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O 5'h0 5'h0 5bit 5'h0 6'b010000

MFLO -- Move from LO

Description: The contents of register LO are moved to the specified register.
Operation: $d = $LO;
Syntax: mflo $d
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O 5'h0 5'h0 5bit 5'h0 6'b010010

MTHI -- Move to HI

Description: The contents of register $s are moved to $HI.
Operation: $HI=$s;
Syntax: mthi $s
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O 5'bit 5'h0 5'h0 5'h0 6'b010001

MTLO -- Move to LO

Description: The contents of register $s are moved to $HI.
Operation: $LO=$s;
Syntax: mtlo $s
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O 5'bit 5'h0 5'h0 5'h0 6'b010011


MULT -- Multiply

Description: Multiplies $s by $t and stores the result in $LO.
Operation: $LO = $s * $t;
Syntax: mult $s, $t
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O 5bit 5bit 5'h0 5'h0 6'b011000

MULTU -- Multiply unsigned

Description: Multiplies $s by $t and stores the result in $LO.
Operation: $LO = $s * $t;
Syntax: multu $s, $t
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O 5bit 5bit 5'h0 5'h0 6'b011001

NOR -- Bitwise nor

Description: Bitwise logical nors two registers and stores the result in a register
Operation: $d = ~($s | $t);
Syntax: nor $d, $s, $t
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O 5bit 5bit 5bit 5'h0 6'b100111


OR -- Bitwise or

Description: Bitwise logical ors two registers and stores the result in a register
Operation: $d = $s | $t;
Syntax: or $d, $s, $t
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O 5bit 5bit 5bit 5'h0 6'b100101

ORI -- Bitwise or immediate

Description: Bitwise ors a register and an immediate value and stores the result in a register
Operation: $t = $s | imm;
Syntax: ori $t, $s, imm
Encoding:
OPCODE Source Target Immediate
6'b001101 5bit 5bit 16bit

SB -- Store byte

Description: The least significant byte of $t is stored at the specified address.
Operation: MEM[$s + imm] = (0xff & $t);
Syntax: sb $t, imm($s)
Encoding:
OPCODE Source Target Immediate
6'b101000 5bit 5bit 16bit

SH -- Store Half

Description: The least significant half word of $t is stored at the specified address.
Operation: MEM[$s + imm] = (0xffff & $t);
Syntax: sh $t, imm($s)
Encoding:
OPCODE Source Target Immediate
6'b101001 5bit 5bit 16bit


SLL -- Shift left logical

Description: Shifts a register value left by the shift amount listed in the instruction and places the result in a third register. Zeroes are shifted in.
Operation: $d = $t << h;
Syntax: sll $d, $t, h
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O 5bit 5bit 5bit h 6'b000000

SLLV -- Shift left logical variable

Description: Shifts a register value left by the value in a second register and places the result in a third register. Zeroes are shifted in.
Operation: $d = $t << $s;
Syntax: sllv $d, $t, $s
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O 5bit 5bit 5bit ????? 6'b000100

SLT -- Set on less than (signed)

Description: If $s is less than $t, $d is set to one. It gets zero otherwise.
Operation: if $s < $t $d = 1; else $d = 0;
Syntax: slt $d, $s, $t
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O 5bit 5bit 5bit 5'h0 6'b101010

SLTI -- Set on less than immediate (signed)

Description: If $s is less than immediate, $t is set to one. It gets zero otherwise.
Operation: if $s < imm $t = 1; else $t = 0;
Syntax: slti $t, $s, imm
Encoding:
OPCODE Source Target Immediate
6'b001010 5bit 5bit 16bit

SLTIU -- Set on less than immediate unsigned

Description: If $s is less than the unsigned immediate, $t is set to one. It gets zero otherwise.
Operation: if $s < imm $t = 1; else $t = 0;
Syntax: sltiu $t, $s, imm
Encoding:
OPCODE Source Target Immediate
6'b001011 5bit 5bit 16bit

SLTU -- Set on less than unsigned

Description: If $s is less than $t, $d is set to one. It gets zero otherwise.
Operation: if $s < $t $d = 1; else $d = 0;
Syntax: sltu $d, $s, $t
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O 5bit 5bit 5bit 5'h0 6'b101011

SRA -- Shift right arithmetic

Description: Shifts a register value right by the shift amount (shamt) and places the value in the destination register. The sign bit is shifted in.
Operation: $d = $t >> h;
Syntax: sra $d, $t, h
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O 5bit 5bit 5bit h 6'b000011


SRAV -- Shift right arithmatic variable

Description: Shifts a register value right by the value in a second register and places the result in a third register. the sign bit is shifterd in.
Operation: $d = $t >> $s;
Syntax: srav $d, $t, $s
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O 5bit 5bit 5bit ????? 6'b000111


SRL -- Shift right logical

Description: Shifts a register value right by the shift amount (shamt) and places the value in the destination register. Zeroes are shifted in.
Operation: $d = $t >> h;
Syntax: srl $d, $t, h
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O 5bit 5bit 5bit h 6'b000010

SRLV -- Shift right logical variable

Description: Shifts a register value right by the amount specified in $s and places the value in the destination register. Zeroes are shifted in.
Operation: $d = $t >> $s;
Syntax: srlv $d, $t, $s
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O 5bit 5bit 5bit 5'h0 6'b000110

SUB -- Subtract

Description: Subtracts two registers and stores the result in a register(Exception by Overflow)
Operation: $d = $s - $t;
Syntax: sub $d, $s, $t
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O 5bit 5bit 5bit 5'h0 6'b100010

SUBU -- Subtract unsigned

Description: Subtracts two registers and stores the result in a register
Operation: $d = $s - $t;
Syntax: subu $d, $s, $t
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O 5bit 5bit 5bit 5'h0 6'b100011

SW -- Store word

Description: The contents of $t is stored at the specified address.
Operation: MEM[$s + imm] = $t;
Syntax: sw $t, imm($s)
Encoding:
OPCODE Source Target Immediate
6'b101011 5bit 5bit 16bit

SYSCALL -- System call

Description: Generates a software interrupt.
Operation:
Syntax: syscall
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O ????? ????? ????? ????? 6'b001100

XOR -- Bitwise exclusive or

Description: Exclusive ors two registers and stores the result in a register
Operation: $d = $s ^ $t;
Syntax: xor $d, $s, $t
Encoding:
OPCODE Source Target Destination Shift Function
6fb‚O‚O‚O‚O‚O‚O 5bit 5bit 5bit ????? 6'b100110

XORI -- Bitwise exclusive or immediate

Description: Bitwise exclusive ors a register and an immediate value and stores the result in a register
Operation: $t = $s ^ imm;
Syntax: xori $t, $s, imm
Encoding:
OPCODE Source Target Immediate
6'b001110 5bit 5bit 16bit