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procedure Scan;

begin

GetName;

Token := KWcode[Lookup(Addr(KWlist), Value, 4) + 1];

end;

{–}

{ Match a Specific Input String }

procedure MatchString(x: string);

begin

if Value <> x then Expected('''' + x + '''');

end;

{–}

{ Generate a Unique Label }

function NewLabel: string;

var S: string;

begin

Str(LCount, S);

NewLabel := 'L' + S;

Inc(LCount);

end;

{–}

{ Post a Label To Output }

procedure PostLabel(L: string);

begin

WriteLn(L, ':');

end;

{–}

{ Output a String with Tab }

procedure Emit(s: string);

begin

Write(TAB, s);

end;

{–}

{ Output a String with Tab and CRLF }

procedure EmitLn(s: string);

begin

Emit(s);

WriteLn;

end;

{–}

{ Parse and Translate an Identifier }

procedure Ident;

begin

GetName;

if Look = '(' then begin

Match('(');

Match(')');

EmitLn('BSR ' + Value);

end

else

EmitLn('MOVE ' + Value + '(PC),D0');

end;

{–}

{ Parse and Translate a Math Factor }

procedure Expression; Forward;

procedure Factor;

begin

if Look = '(' then begin

Match('(');

Expression;

Match(')');

end

else if IsAlpha(Look) then

Ident

else begin

GetNum;

EmitLn('MOVE #' + Value + ',D0');

end;

end;

{–}

{ Parse and Translate the First Math Factor }

procedure SignedFactor;

var s: boolean;

begin

s := Look = '-';

if IsAddop(Look) then begin

GetChar;

SkipWhite;

end;

Factor;

if s then

EmitLn('NEG D0');

end;

{–}

{ Recognize and Translate a Multiply }

procedure Multiply;

begin

Match('*');

Factor;

EmitLn('MULS (SP)+,D0');

end;

{–}

{ Recognize and Translate a Divide }

procedure Divide;

begin

Match('/');

Factor;

EmitLn('MOVE (SP)+,D1');

EmitLn('EXS.L D0');

EmitLn('DIVS D1,D0');

end;

{–}

{ Completion of Term Processing (called by Term and FirstTerm }

procedure Term1;

begin

while IsMulop(Look) do begin

EmitLn('MOVE D0,-(SP)');

case Look of

'*': Multiply;

'/': Divide;

end;

end;

end;

{–}

{ Parse and Translate a Math Term }

procedure Term;

begin

Factor;

Term1;

end;

{–}

{ Parse and Translate a Math Term with Possible Leading Sign }

procedure FirstTerm;

begin

SignedFactor;

Term1;

end;

{–}

{ Recognize and Translate an Add }

procedure Add;

begin

Match('+');

Term;

EmitLn('ADD (SP)+,D0');

end;

{–}

{ Recognize and Translate a Subtract }

procedure Subtract;

begin

Match('-');

Term;

EmitLn('SUB (SP)+,D0');

EmitLn('NEG D0');

end;

{–}

{ Parse and Translate an Expression }

procedure Expression;

begin

FirstTerm;

while IsAddop(Look) do begin

EmitLn('MOVE D0,-(SP)');

case Look of

'+': Add;

'-': Subtract;

end;

end;

end;

{–}

{ Parse and Translate a Boolean Condition }

{ This version is a dummy }

Procedure Condition;

begin

EmitLn('Condition');

end;

{–}

{ Recognize and Translate an IF Construct }

procedure Block; Forward;

procedure DoIf;

var L1, L2: string;

begin

Condition;

L1 := NewLabel;

L2 := L1;

EmitLn('BEQ ' + L1);

Block;

if Token = 'l' then begin

L2 := NewLabel;

EmitLn('BRA ' + L2);

PostLabel(L1);

Block;

end;

PostLabel(L2);

MatchString('ENDIF');

end;

{–}

{ Parse and Translate an Assignment Statement }

procedure Assignment;

var Name: string;

begin

Name := Value;

Match('=');

Expression;

EmitLn('LEA ' + Name + '(PC),A0');

EmitLn('MOVE D0,(A0)');

end;

{–}

{ Recognize and Translate a Statement Block }

procedure Block;

begin

Scan;

while not (Token in ['e', 'l']) do begin

case Token of

'i': DoIf;

else Assignment;

end;

Scan;

end;

end;

{–}

{ Parse and Translate a Program }


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