promptHex:      .asciiz "Enter a hexadecimal number i.e.1234ABCD: "
hexInt:         .asciiz "Integer equivalent: "
buffer:         .space  80
hexadecimal:    .space  8
 
la      $a0,    promptHex
               li      $v0,    4
               syscall
 
               li      $v0,    8
               la      $a0,    buffer
               li      $a1,    80
               syscall
 
 
               la      $a0,    buffer
               li      $a1,    64
               jal     hexToInt
               sw      $v0,    integer
 
       li $v0, 4
               la $a0, hexInt
       syscall
 
       li     $v0,     1
               lw     $a0,     integer
       syscall
 
hexToInt:
#-----------------------------------------------------------------
 
               li              $v0,    0
               li              $t1,    0
               li              $t2,    32
 
htoi:
#----------------------------------------------         #shift 16 bits
               lbu             $t0,    0($a0)
       addi    $t1,    $t1,    -4
               beq             $t0,    48,             Number
               beq             $t0,    49,             Number
               beq             $t0,    50,             Number
               beq             $t0,    51,             Number
               beq             $t0,    52,             Number
               beq             $t0,    53,             Number
               beq             $t0,    54,             Number
               beq             $t0,    55,             Number
               beq             $t0,    56,             Number
               beq             $t0,    57,             Number
               beq             $t0,    65,     Letter
               beq             $t0,    66,     Letter
               beq             $t0,    67,     Letter
               beq             $t0,    68,     Letter
               beq             $t0,    69,     Letter
               beq             $t0,    70,     Letter
               beq             $t0,    0x00,   Done
Number:
#----------------------------------------------         #convert number
               addi    $t0,    $t0,    -48
               sll             $t0,    $t0,    $t1
               add             $v0,    $v0,    $t0
               addi    $a0,    $a0,    -1
               addi    $a1,    $a1,    -7
               j htoi
Letter:
#----------------------------------------------         #convert letter
       addi    $t0,    $t0,    -55
       sll     $t0,    $t0,    $t1
       add     $v0,    $v0,    $t0
               addi    $a0,    $a0,    -1
               addi    $a1,    $a1,    -7
       j       htoi
Done:
#----------------------------------------------         #end subroutine
               jr  $ra
--------------------