mips memcpy

#made by xerpi

.text
.global mips_memcpy
.set noreorder


mips_memcpy:
    move $t0, $a0   #backup destination

_loop_memcpy:
    beqz $a2, _e_memcpy    #if(size==0) return
    nop
    bge $a2, 4, _4_memcpy  #if(size >= 4) goto _4_memcpy
    nop
    bge $a2, 2, _2_memcpy  #if(size >= 2) goto _2_memcpy
    nop
    _1_memcpy:
        lb $t1, ($a1)       #u8 x = *in
        sb $t1, ($a0)       #*out = x
        addi $a0, $a0, 1    #in++
        addi $a1, $a1, 1    #out++
        j _loop_memcpy
        addi $a2, $a2, -1   #size--
    _2_memcpy:
        lh $t1, ($a1)      #u16 x = *in
        sh $t1, ($a0)      #*out = x
        addi $a0, $a0, 2   #in+=2
        addi $a1, $a1, 2   #out+=2
        j _loop_memcpy
        addi $a2, $a2, -2  #size-=2
    _4_memcpy:
        lw $t1, ($a1)      #u32 x = *in
        sw $t1, ($a0)      #*out = x
        addi $a0, $a0, 4   #in+=4
        addi $a1, $a1, 4   #out+=4
        j _loop_memcpy
        addi $a2, $a2, -4  #size-=4

_e_memcpy:
    jr $ra
    move $v0, $t0