[SOLVED] Print all digits of a given number in LMC

Print all digits of a given number in LMC

I need to print all digits of a given number in LMC. I tried with this code who gives me the last digit but I don't know how to keep going with the other digits.

    INP
L0  STA R0
    SUB R1
    BRP L0
    LDA R0
    OUT
    HLT
R0  DAT 000
R1  DAT 010

Solution

The code you have will output the least significant digit. To produce the other two digits (knowing that the LMC is limited to 3 digit numbers), first subtract 100 repeatedly and count how many times you could do that: this would be the first digit to output. Then subtract 10 repeatedly and count... and finally output the remainder.

For the repeated subtraction you need a loop. You could consider using self modifying code in order to reuse the same loop for subtracting 100 and later on for subtracting 10. But you might as well write a separate loop for each of these two cases:

#input:321
          INP
          STA input
          LDA zero   ; prepare for finding first digit
          BRA enter1

loop1     STA input
          LDA digit  ; increment digit
          ADD one
enter1    STA digit
          LDA input
          SUB hundred ; output number of 100s
          BRP loop1
          LDA digit
          OUT

          LDA zero   ; prepare for finding second digit
          BRA enter2

loop2     STA input
          LDA digit  ; increment digit
          ADD one
enter2    STA digit
          LDA input
          SUB ten
          BRP loop2
          LDA digit  ; output number of 10s
          OUT
          LDA input  ; output remainder
          OUT
zero      HLT

one       DAT 001
ten       DAT 010
hundred   DAT 100

input     DAT
digit     DAT

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