Write a program in MIPS assembly language to convert an ASCI

Write a program in MIPS assembly language to convert an ASCII number string containing positive and negative integer decimal strings, to an integer. Your program should expect register $a0 to hold the address of a nullterminated string containing some combination of the digits 0 through 9. Your program should compute the integer value equivalent to this string of digits, then place the number in register $v0. If a non-digit character appears anywhere in the string, your program should stop with the value 1 in register $v0. For example, if register $a0 points to a sequence of three bytes 50ten, 52ten, 0ten (the nullterminated string “24”), then when the program stops, register $v0 should contain the value 24ten

Solution

.data

#ASCII string

asciiStr: .asciiz   \"+123\"

     .text

main:

     #call procedure to convert

     jal procConvert

     move      $a1, $v0

     #print $v0 result

     li   $v0,1

     syscall

     #stop program

     li $v0,10

     syscall

    

procConvert:

     la   $a0, asciiStr      #load ascii string

     #load hexadecimal value for \'+\' in $t5              

     li   $t5, 0x2B

     #load hexadecimal value for \'0\' in $t6    

     li   $t6, 0x30         

     #load hexadecimal value of \'9\' in $t7

     li   $t7, 0x39              

     #pointer to the asciiStr

     add $t0, $0, $a0           

     #get the sign of the ascii number

     lbu $t1, 0($t0)            

     #store the sign of the ascii number

     add $t3, $t1, $0           

     #move to the next character

     addiu     $t0, $t0, 1

     #load the character

     lbu $t1, 0($t0)

     #initialize $v0

     li   $v0, 0   

#loop to convert asciiStr to decimal Str            

REPEATCONVERSION:

     #check if charcter is less than \'0\'

     slt $t4, $t1, $t6

     #if so, then jump to ExitLoop             

     bne $t4, $0, ExitLoop

     #check if character is greater than \'9\'

     slt $t4, $t1, $t7

     #if so, then jump to    ExitLoop

     beq $t4, $0, ExitLoop

     #convert character to int

     subu $t1, $t1, $t6

     #$v0=$v0*10            

     mul $v0, $v0, 10

     #now add the int to $v0

     add $v0, $v0, $t1

     #move to the next character in the asciiStr         

     addiu     $t0, $t0, 1  

     #Get the next character     

     lbu $t1, 0($t0)            

     #check chracter is not null.

     #If so, repeat the conversion process

     bne $t1, $0, REPEATCONVERSION

     #check asciiStr is positive. If not jump to NOTPOSITIVE  

     bne $t3, $t5, NOTPOSITIVE

     #stop program          

     jr   $ra

#for negative asciiStr           

NOTPOSITIVE:

     #convert $v0 to negative using $v0=$0-$v0

     sub $v0, $0, $v0           

     #jump to program end

     jr   $ra

#exit loop for null string                

ExitLoop:

     li   $v0, -1

     jr $ra