MIPS_Substring

# 2. Assume a null terminated string is stored in a memory location. Write an MIPS assembly language program
# that will return the base address of a query substring(first occurance) passed as a parameter to the function.
# If the substring doesn't exist, it will return null or zero(0).

.data 
string: .asciiz "kamna"
substring: .asciiz "mna"
.text

main: la $a0,string                       # Load address of string
	la $a1,substring                        # Load address of substring
	j check

  check: move $t0,$a1                     # mpoved to t0 to initialize substring(if required)
	loop1: 
	lb $t1, 0($a1)                          # Loading substring's byte in t1
	 beqz $t1,exit                          # check for null value
         
	 
	loop2: 
		lb $t2,0($a0)
		beqz $t2,exit1
		addi $a0,$a0,1
		bne $t1,$t2,dodo                    # if values not equal jump to dodo
		addi $a1,$a1,1                      # Increasing substring pointer
		j loop1

       dodo:  bne $a1,$t0,didi         # If char wasn't first char of substring
	                                     # you need to decrese add. of string's char
	        j loop1

 	didi: addi $a0,$a0,-1
		move $a1,$t0
	        j loop1

 exit: move $t3,$t0
  j ka
 exit1: move $t3,$zero
ka: 
li $v0,10
syscall