What is a better way to turn a user-inputted hexadecimal string into a binary in MIPS?

0

I'm taking a computer architecture class, and they're having us use MIPS assembly. Our current assignment is asking us to take a user-inputted hex string, and turn it into a binary one. The code I've written "works", but it's horrible, to say the least. What would be a better approach to doing this? I need the binary-converted string in a variable, and this is the only way I was able to do it:

### THIS CODE IS AWFUL ###
.data
    inputPrompt: .asciiz    "Please enter a 32-bit hexadecimal integer: "   
    outputMsg:   .asciiz    "\nConverted Hexadecimal String: "

    hexInput: .space 9      # Enough space for 8 digit hex number

    binaryConvertedStr: .space 33   # Enough space for a 32 digit binary number

    var0: .asciiz "0000"
    var1: .asciiz "0001"
    var2: .asciiz "0010"
    var3: .asciiz "0011"
    var4: .asciiz "0100"
    var5: .asciiz "0101"
    var6: .asciiz "0110"
    var7: .asciiz "0111"
    var8: .asciiz "1000"
    var9: .asciiz "1001"
    varA: .asciiz "1010"
    varB: .asciiz "1011"
    varC: .asciiz "1100"
    varD: .asciiz "1101"
    varE: .asciiz "1110"
    varF: .asciiz "1111"

    sym0: .word 0x00000030
    sym1: .word 0x00000031
    sym2: .word 0x00000032
    sym3: .word 0x00000033
    sym4: .word 0x00000034
    sym5: .word 0x00000035
    sym6: .word 0x00000036
    sym7: .word 0x00000037
    sym8: .word 0x00000038
    sym9: .word 0x00000039 
    symA: .word 0x00000041
    symB: .word 0x00000042
    symC: .word 0x00000043
    symD: .word 0x00000044
    symE: .word 0x00000045
    symF: .word 0x00000046

.text
    main:   li $v0, 4
        la $a0, inputPrompt
        syscall                 # Displays a message prompting user for 8 digit hex number

        li $v0, 8               
        la $a0, hexInput        
        li $a1, 9        
        syscall                 # Stores user-inputted 8 digit hex number into "hexInput"


        la $t0, hexInput                # Loads address of hexInput into t0
        la $t1, binaryConvertedStr      # Loads address of (pre-converted) binaryConvertedStr into t1

    findChar:
        lbu $s0, ($t0)              # Loads Nth byte of t0 (hexInput) into s0
        beqz $s0, Done              # Checks if hexInput's null terminator has been reached

        ## LONG, TERRIBLE WAY OF CHECKING WHAT EACH INTEGER OF hexInput IS. JUMPS TO writeToConverted IF FOUND. ##
        la $t9, sym0
        lbu $t8, ($t9)
        la $t2, var0
        beq $s0, $t8, writeToConverted      
        la $t9, sym1
        lbu $t8, ($t9)
        la $t2, var1
        beq $s0, $t8, writeToConverted
        la $t9, sym2    
        lbu $t8, ($t9)
        la $t2, var2
        beq $s0, $t8, writeToConverted    
        la $t9, sym3
        lbu $t8, ($t9)
        la $t2, var3
        beq $s0, $t8, writeToConverted
        la $t9, sym4
        lbu $t8, ($t9)
        la $t2, var4
        beq $s0, $t8, writeToConverted
        la $t9, sym5    
        lbu $t8, ($t9)
        la $t2, var5
        beq $s0, $t8, writeToConverted    
        la $t9, sym6
        lbu $t8, ($t9)
        la $t2, var6
        beq $s0, $t8, writeToConverted
        la $t9, sym7
        lbu $t8, ($t9)
        la $t2, var7
        beq $s0, $t8, writeToConverted
        la $t9, sym8
        lbu $t8, ($t9)
        la $t2, var8
        beq $s0, $t8, writeToConverted
        la $t9, sym9    
        lbu $t8, ($t9)
        la $t2, var9
        beq $s0, $t8, writeToConverted    
        la $t9, symA    
        lbu $t8, ($t9)
        la $t2, varA
        beq $s0, $t8, writeToConverted    
        la $t9, symB
        lbu $t8, ($t9)
        la $t2, varB
        beq $s0, $t8, writeToConverted
        la $t9, symC
        lbu $t8, ($t9)
        la $t2, varC
        beq $s0, $t8, writeToConverted
        la $t9, symD
        lbu $t8, ($t9)
        la $t2, varD
        beq $s0, $t8, writeToConverted
        la $t9, symE
        lbu $t8, ($t9)
        la $t2, varE
        beq $s0, $t8, writeToConverted
        la $t9, symF
        lbu $t8, ($t9)
        la $t2, varF
        beq $s0, $t8, writeToConverted



    writeToConverted:               # Writes the converted hex digit into binary, then writes that binary string to binaryConvertedStr
        lbu $s1, ($t2)              # Loads next byte of var(N) into s1
        beqz $s1, increment         # Checks if var(N)'s null terminator has been reached; if so, then jumps back to findChar after incrementing 
                                # t0 (hexInput's address) by 1
        sb $s1, ($t1)               # Writes s1 (byte of var(N)) to t1 (binaryConvertedStr)
        addi $t1, $t1, 1            # Increments the address-to-be-edited of t1 (binaryConvertedStr)
        addi $t2, $t2, 1            # Increments the address-to-be-read of t2 (var(N))
        j writeToConverted          # Loops back around until the null terminator of var(N) is found

    increment:                  # Increments t0 (hexInput's address) by 1
        addi $t0, $t0, 1
        j findChar              # Loop back to findChar


    Done:                       # Tells the user what their string in binary is. 
        li $v0, 4
        la $a0, outputMsg
        syscall

        li $v0, 4
        la $a0, binaryConvertedStr
        syscall

    li $v0, 10
    syscall

assembly
mips
cpu-architecture
mars
asked on Stack Overflow Feb 19, 2020 by Devon Caron

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