[MIPS] J, JAL, and JR commands

J Jump
Jal Jump and Link
Jr Jump Register

Jump:

Jumps to the target offset, a delay slot is needed.
Syntax:

J $Offset
Noop // This is the delay slot

Best used to call subroutines.

Jump and Link:

Executes the next line, then jumps to the target offset, then changes the return value (ra) value so it jumps to the offset after the delay slot.
Syntax:

Jal $Offset
Noop // Delay slot, so when the next line is executed nothing happens
{Now here is where the ra will jump to}

Best used for function calls because after the function is done it will return to the offset after the noop.

Jump Register:

Jumps to the offset stored in a register. A delay slot is needed.
Syntax:

Lui t0, $0880 // Loads 0880 into t0, now t0 holds the offse 08800000
Jr t0 // Jumps to the offset 08800000
Noop

Now if you are confused why we didn't do this to load the offset:

Lui t0, $0880
Lw t0, $0000(t0)

Is because the LUI command loads 16 bits into a register and the right 16Bits are zeros. So lui t0, $0880 will load the offset 08800000 into the register t0

So the syntax will jump to the offset 08800000

Tips for these commands:

Use J for calling subroutines
Use Jal for calling functions
Use Jr for ending a subroutine by jumping to the return address (ra)
Always use a delay slot (A noop on the next offset) when using Jump commands

END TUTORIAL