/ ; *************************************************** /
/ ; *** HiLow.68                                    *** /
/ ; *** Tests branching instructions of Sim68k      *** /
/ ; *** Tests BRA, BEQ, BGE, CMP, TST               *** /
/ ; *** Also uses MOVE, ADDQ, INP, DSP, DSR and HLT *** /
/ ; *************************************************** /
/  /
/ ; Branching instructions  (and status bits updating)  are  hard /
/ ; to verify. Here is a little game that will test some of these /
/ ; instructions.  Complete your verification with your own tests. /
/  /
/ ; This is the High-Low Game. /
/ ; Here is what it would look like in Pascal: /
/ ; /
/ ;    R.W := $FFFF;     { Initializes R (Result)            } /
/ ;    C.W := $0000;     { Initializes C (Counter)           } /
/ ;    Repeat /
/ ;       Readln(D0.B)      { "Random" number to find        } /
/ ;    Until (D0.B <> 0);   { D0 must be different from 0    } /
/ ;    Read (D1.B);         { Player is guessing a number    } /
/ ;                 { Player can enter 0 to exit the game    } /
/ ;    While (D1.B <> 0) And (R.W <> 0) Do /
/ ;     Begin /
/ ;       If (D1.B <> D0.B) /
/ ;       then /
/ ;          If (D1.B < D0.B) /
/ ;          then /
/ ;             R.W := $1  { Too low } /
/ ;          else /
/ ;             R.W := $2  { Too high } /
/ ;       else /
/ ;          R.W := $0;    { Found! } /
/ ;       Writeln (R.W);   { Display the message } /
/ ;       Inc(C.W); /
/ ;       If R.W <> 0 /
/ ;       then /
/ ;          Read (D1.B) /
/ ;     End; /
/ ;    Writeln (C.W) { Display the number of guesses } /
/  /
/  /
/ ;    Assembly Language       OpCode  Oper1   Oper2 /
/ ;                           MSB LSB MSB LSB MSL LSB /
/ ;-------------------------------------------------- /
/ ; Branch to the first instruction /
/ BRA.W  @Repeat             ; / $92 $60 $00 $0E
/  /
/ ; Declarations /
/ DEF.W  @R,    #$FFFF     ; / $FF $FF
/ DEF.W  @C,    #$0000     ; / $00 $00
/ DEF.W  @Zero, #$0000     ; / $00 $00
/ DEF.W  @One,  #$0001     ; / $00 $01
/ DEF.W  @Two,  #$0002     ; / $00 $02
/ ; Choose a random number not 0 /
/ LABEL  @Repeat           ; /
/     INP.B  D0            ; / $E0 $00
/     BEQ.W  @Repeat       ; / $A2 $60 $00 $0E
/  /
/ ; Player is guessing a number /
/     INP.B  D1            ; / $E0 $10
/  /
/ LABEL  @While            ; /
/     TST.B  D1            ; / $88 $10
/     BEQ.W  @End          ; / $A2 $60 $00 $62
/     TST.W  @R            ; / $8A $60 $00 $04
/     BEQ.W  @End          ; / $A2 $60 $00 $62
/  /
/ ; D1 <> D0 ? /
/     CMP.B  D0, D1        ; / $81 $01
/     BEQ.W  @Found        ; / $A2 $60 $00 $2E
/     BRA.W  @TooLow       ; / $92 $60 $00 $38
/  /
/ LABEL  @Found            ; /
/     MOVE.W @Zero, @R     ; / $C3 $66 $00 $08 $00 $04
/     BRA.W  @Display      ; / $92 $60 $00 $4C
/  /
/ LABEL  @TooLow           ; /
/     BGE.W  @TooHigh      ; / $B2 $60 $00 $46
/     MOVE.W @One, @R      ; / $C3 $66 $00 $0A $00 $04
/     BRA.W  @Display      ; / $92 $60 $00 $4C
/  /
/ LABEL  @TooHigh          ; /
/     MOVE.W @Two, @R      ; / $C3 $66 $00 $0C $00 $04
/ ; No need for a branching instruction to @Display... /
/  /
/ LABEL  @Display          ; /
/ ; Display the message /
/     DSP.W  @R            ; / $EA $60 $00 $04
/ ; Increment the number of guesses (C) /
/     ADDQ.W #$1, @C       ; / $0A $16 $00 $06
/     TST.W  @R            ; / $8A $60 $00 $04
/     BEQ.W  @End          ; / $A2 $60 $00 $62
/     INP.B  D1            ; / $E0 $10
/  /
/ LABEL  @EndWhile         ; /
/     BRA.W  @While        ; / $92 $60 $00 $16
/  /
/ LABEL  @End              ; /
/ ; Display the number of guesses /
/     DSP.W  @C            ; / $EA $60 $00 $06
/     HLT.B                ; / $F8 $00