Saving integers as Strings in MIPS

Question

Hello , i was just wondering, is there any way in MIPS to store a summation of numbers as a string and later read them byte by byte, for example:

the sum 657 -> sw into a .ascii directive -> later lb on the first index to get 6 (in ascii code) same with 5 and so on

Is this possible ?

//Thx in advance

Answer 1

Of course. The ".ascii" directive is none but a .byte directive focused on the storage of ASCII text

   .ascii "PP"

is like

   .byte 80,80

You can use .space to make room for your ASCII string, and then use the buffer in the convertion from integer to ASCII, if you mean this by "sw into .ascii directive" of in integer. The following code converts the "binary number" into a ASCII string using itoa and prints it (just for testing) with print_string. The function uses a buffer and returns the pointer to the first ASCII digit usable for printing. This could be used as a first helper function for a sprintf-like function implementation.

       .data

buffer:
         .space 32


      .text
      # the main supposes env. like spim or MARS
main:
      li   $a0, 1234      # a number
      jal  itoa
      move $a0, $v0
      li   $v0, 4         # print_string    
      syscall
      li   $v0, 10
      syscall             # exit

itoa:
      la   $t0, buffer    # load buf
      add  $t0, $t0, 30   # seek the end
      sb   $0, 1($t0)     # null-terminated str
      li   $t1, '0'  
      sb   $t1, ($t0)     # init. with ascii 0
      slt  $t2, $a0, $0   # keep the sign
      li   $t3, 10        # preload 10
      beq  $a0, $0, iend  # end if 0
      neg  $a0, $a0
loop:
      div  $a0, $t3       # a /= 10
      mflo $a0
      mfhi $t4            # get remainder
      add  $t4, $t4, $t1  # convert to ASCII digit
      sb   $t4, ($t0)     # store it
      sub  $t0, $t0, 1    # dec. buf ptr
      bne  $a0, $0, loop  # if not zero, loop
      addi $t0, $t0, 1    # adjust buf ptr
iend:
      beq  $t2, $0, nolz  # was < 0?
      addi $t0, $t0, -1
      li   $t1, '-'
      sb   $t1, ($t0)
nolz:
      move $v0, $t0      # return the addr.
      jr   $ra           # of the string

After you have $v0 in the main, lb R, ($v0) picks "1", lb R, 1($v0) picks second digit (2) and so on; remember the string is null-terminated, so if you pick 0 (numeric), you have to stop