Arithmetic Pseudoinstructions

With the non-extended assembler there is an  addu d,s,t  instruction where d, s, and t are registers, and an  addiu d,s,im  instruction where im is an immediate operand.

With the extended assembler the  addu d,s,x  instruction translates into different basic instructions depending on x. x can be a register, a 16-bit immediate operand, or a larger immediate operand.

Examine the following instruction (for the extended assembler):

addu $t0,$s0,40000

The decimal value 40000 is too large to represent in 16 bits, (the range for 16 bits is -32768 to +32767) so the instruction cannot be translated into an addiu instruction. Two instructions must be used to add $s0 to 40000₁₀ and to place the result in $t0.

addu $s1,$s0,40000  ==  

li   _____,40000    # use pseudoinstruction li
addu $s1,$s0,_____  # perform 32-bit addition