Assembly Random Number within Range using Easy 68K (68000)

Question

I\'m creating a simple black jack game using the Easy 68K simulator and need to use a random number to assign the cards. My cards must be in the range 2 to 11. I seem to be gett

Answer 1

You need to use the right mask depending on your interval (minimum and maximum), This code will solve all your problems, it take two arguments : Minimum in D5 and Maximum in D6, it also uses D0, D7 and A1.

RAND_GEN
    SUB     D5,D6             ;You should give Min in D5 and Max in D6
    MOVE    D6,D7
    ADDI     #1,D6
    MULU    #$FFFF,D7
    LEA     SEED,A1
    MOVE.B  #8,d0
    TRAP    #15
    ADD    (A1),D1
    MULU  #$FFFF,D1
    EOR.L     #$F321F23A,D1
    MOVE    D1,(A1)
    AND.L   D7,D1    ;PREVENT OVERFLOW FOR (Max-Min)
    DIVU    D6,D1         ;time count / (Max-Min)
    SWAP    D1              ;swap upper and lower words of D1 to put remainder in low word
    ADD  D5,d1           ;D1.W contains number in the range of (Min,Max)
    RTS

* Put variables and constants here
SEED
    DC.W    1

The SEED will be by default 1 at the start of program and updates itself automatically after each RAND_GEN call, you can also change it at any time.

Tested on EASY68K.