sprintf:  addi $sp, $sp, -16
          sw $s0, 0($sp)     #$s0 will char at $a0[i]
          sw $s1, 4($sp)     #$s1 will hold wich argument we deal with
          sw $s2, 8($sp)     #mini stack pointer
          sw $s3, 12($sp)    #which are to use
          add $s3, $0, $0
          add $v0, $0, $0

loop:     lb $s0, 0($a1)
          beqz $s0, end
          beq  $s0, '%', format #if ($s0 == '%') goto format; 


#handle normal charecters.
          sb $s0, 0($a0)   #if the charecter is not % than we simply
          addi $a0, $a0, 1 #put in the new string and incriment $a0
          addi $a1, $a1, 1 #incriment $a1 to point to next char in string
          addi $v0, $v0, 1 #incriment output char count 
          b loop


#handle other parts of the string
format:   bne $s3, $0, use_a3
  use_a2: add $s1, $a2, $0
          b continue_format
  use_a3: add $s1, $a3, $0
  continue_format: 
          addi $s3, $s3, 1
          addi $a1, $a1, 1         #a1 gets next place in string
          lb $s0, 0($a1)           #load charecter after the %
          addi $a1, $a1, 1         #incriment $a1 past the format char
          beq $s0, 'x', hex
          beq $s0, 'd', decimal_integer  
          beq $s0, 'c', char
          beq $s0, 's', string



percent:
          addi $t0, $0, '%'
          sb $t0, 0($a0)
          addi $a0, $a0, 1
          addi $v0, $v0, 1
          b loop



decimal_integer:
          bgez $s1, posative
  negative:
          addi $t0, $0, '-'
          sb $t0, 0($a0)
          addi $a0, $a0, 1
          addi $v0, $v0, 1
          neg $s1,$s1
  posative:
          rem $t0, $s1, 10
          addi $t0, $t0, 48
          addi $sp, $sp, -1
          addi $s2, $s2, -1
          sb $t0, 0($sp)
          div $s1, $s1, 10
          bne $s1, $0, posative
  integer_output:
          beqz $s2, loop 
          lb $t0, 0($sp)
          sb $t0, 0($a0)
          addi $sp, $sp, 1
          addi $s2, $s2, 1  
          addi $a0, $a0, 1
          addi $v0, $v0, 1
          b integer_output


hex:      addi $t0, $0, '0'
          sb $t0, 0($a0)
          addi $t0, $0, 'x'
          sb $t0, 1($a0)
          addi $a0, $a0, 2 
          bgez $s1, posative_hex
  negative_hex:
          addi $t0, $0, '-'
          sb $t0, 0($a0)
          addi $a0, $a0, 1
          addi $v0, $v0, 1
          neg $s1,$s1
  posative_hex:
          rem $t0, $s1, 16
          blt $t0, 10, number
  letter: addi $t0, $t0, 39
  number: addi $t0, $t0, 48
          addi $sp, $sp, -1  
          addi $s2, $s2, -1
          sb $t0, 0($sp)  
          div $s1, $s1, 16
          bne $s1, $0, posative_hex
  hex_output:
          beqz $s2, loop   
          lb $t0, 0($sp)
          sb $t0, 0($a0)   
          addi $sp, $sp, 1
          addi $s2, $s2, 1   
          addi $a0, $a0, 1
          addi $v0, $v0, 1
          b hex_output 



char:     sb $s1, 0($a0) 
          addi $a0, $a0, 1
          addi $v0, $v0, 1
          b loop




string:  add $t1, $s1, $0
string_loop:                        
         lb $t0,0($t1)
         beqz $t0,loop
         sb $t0,0($a0)
         addi $a0, $a0, 1
         addi $v0, $v0, 1
         addi $t1,$t1,1
         b string_loop





end:      sb $0, 0($a0)      #add null charecter
          lw $s3, 12($sp)
          lw $s2, 8($sp)
          lw $s1, 4($sp)     #pop $s1 back off
          lw $s0, 0($sp)     #pop $s0 back off
          addi $sp, $sp, 16  #update stack (4*2)
          jr $ra             #return to calling function