75 Hard Time Tracker in MMIX

75easy.mms

    LOC #1000

START_TIME IS 1767310000
DAY  IS 86400

Main
    TRAP   0, Time, 0
    SETI   $1, START_TIME
    SETI   $3, DAY
    MULI   $3, $3, 3        % buffer for 3 days
    ADDU   $1, $1, $3
    SUBU   $0, $255, $1
    BN     $0, Error
    BZ     $0, Done
    SETI   $1, DAY
    DIVU   $0, $0, $1
    JMP    Done

Done
    LDA    $255, Message
    TRAP   0, Fputs, StdOut
    % $0 has number of days
    PUSHJ  $0, PrintDays
    LDA    $255, Unit
    TRAP   0, Fputs, StdOut

    SETI   $255, '\n'       % newline
    TRAP   0, Fputc, StdOut
    SETI   $255, 0
    TRAP   0, Halt, 0

Error
    SETI   $255, -1
    TRAP   0, Halt, 0

Tmp IS $254
Reversed IS $253

% Print $0 as a number
% Algorithm: reverse the number into $253, then print digits in order
PrintDays
    BZ     $0, PrintZero
    
    % Reverse the number: reversed = 0
    SETI   Reversed, 0
    SET    Tmp, $0
    
ReverseLoop
    BZ     Tmp, PrintLoop
    % Extract one digit
    DIVI   $1, Tmp, 10      % $1 = quotient, rR = remainder
    GET    $2, rR           % $2 = digit
    
    % Build reversed number: reversed = reversed * 10 + digit
    MULI   Reversed, Reversed, 10
    ADDU   Reversed, Reversed, $2
    
    SET    Tmp, $1
    JMP    ReverseLoop
    
PrintLoop
    BZ     Reversed, PrintDone
    % Extract rightmost digit from reversed number
    DIVI   $1, Reversed, 10
    GET    $2, rR
    
    % Print digit
    ADDUI  $255, $2, '0'
    TRAP   0, Fputc, StdOut
    
    SET    Reversed, $1
    JMP    PrintLoop
    
PrintZero
    SETI   $255, '0'
    TRAP   0, Fputc, StdOut
    
PrintDone
    POP    0, 0

    LOC Data_Segment
Message
    BYTE  "You have completed ", 0
Unit
    BYTE  " days", 0