private void ProcessLine()
{
if (lexer.PeekAndDiscard(TokenType.EOL))
{
return;
}
if (lexer.PeekAndDiscard(TokenType._Page))
{
return;
}
if (lexer.Peek().Type == TokenType.Id)
{
var id = (string)lexer.Expect(TokenType.Id);
if (lexer.PeekAndDiscard(TokenType.Eq))
{
var exp = ParseExpression();
Assembler.Equate(id, exp);
lexer.PeekAndDiscard(TokenType.EOL);
return;
}
else if (lexer.PeekAndDiscard(TokenType.Colon))
{
Assembler.Label(id);
}
else
{
lexer.Unexpected(lexer.Get());
}
}
switch (lexer.Peek().Type)
{
case TokenType.EOL:
lexer.Get();
return;
case TokenType._Word:
lexer.Get();
ProcessWords(PrimitiveType.Word16);
break;
case TokenType._Dot:
lexer.Get();
lexer.Expect(TokenType.Eq);
lexer.Expect(TokenType._Dot);
lexer.Expect(TokenType.Plus);
var delta = (int)ParseExpression();
emitter.Reserve(delta);
break;
case TokenType.ASR: ProcessSingleOperand(Assembler.Asr); break;
case TokenType.CLR: ProcessSingleOperand(Assembler.Clr); break;
case TokenType.CLRB: ProcessSingleOperand(Assembler.Clrb); break;
case TokenType.BEQ: ProcessBranch(Assembler.Beq); break;
case TokenType.DEC: ProcessSingleOperand(Assembler.Dec); break;
case TokenType.INC: ProcessSingleOperand(Assembler.Inc); break;
case TokenType.JSR: lexer.Get(); Assembler.Jsr(ParseOperands()); break;
case TokenType.MOV: ProcessDoubleOperand(Assembler.Mov); break;
case TokenType.MOVB: ProcessDoubleOperand(Assembler.Movb); break;
case TokenType.RESET: lexer.Get(); Assembler.Reset(); break;
case TokenType.SUB: ProcessDoubleOperand(Assembler.Sub); break;
default:
lexer.Unexpected(lexer.Get());
break;
}
}
public ParsedOperand ParseOperand()
{
var tok = lexer.Get();
switch (tok.Type)
{
case TokenType.Register:
return(new ParsedOperand
{
Type = AddressMode.Register,
Register = arch.GetRegister((string)tok.Value)
});
case TokenType.Hash:
tok = lexer.Get();
switch (tok.Type)
{
case TokenType.Id:
return(new ParsedOperand
{
Type = AddressMode.Immediate,
Symbol = asm.Symtab.CreateSymbol((string)tok.Value)
});
default:
lexer.Unexpected(tok);
return(null);
}
case TokenType.At:
var op = ParseOperand();
switch (op.Type)
{
case AddressMode.Register: op.Type = AddressMode.RegDef; break;
case AddressMode.RegDef:
case AddressMode.AutoIncrDef:
case AddressMode.AutoDecrDef:
case AddressMode.IndexedDef:
throw new FormatException("Can't re-defer.");
case AddressMode.AutoIncr: op.Type = AddressMode.AutoIncrDef; break;
case AddressMode.AutoDecr: op.Type = AddressMode.AutoDecrDef; break;
case AddressMode.Indexed: op.Type = AddressMode.IndexedDef; break;
}
return(op);
case TokenType.Minus:
lexer.Expect(TokenType.LParen);
var regStr = (string)lexer.Expect(TokenType.Register);
lexer.Expect(TokenType.RParen);
return(new ParsedOperand
{
Type = AddressMode.AutoDecr,
Register = arch.GetRegister(regStr),
});
case TokenType.LParen:
regStr = (string)lexer.Expect(TokenType.Register);
lexer.Expect(TokenType.RParen);
if (lexer.PeekAndDiscard(TokenType.Plus))
{
return(new ParsedOperand
{
Type = AddressMode.AutoIncr,
Register = arch.GetRegister(regStr)
});
}
else
{
return(new ParsedOperand
{
Type = AddressMode.RegDef,
Register = arch.GetRegister(regStr)
});
}
default:
return(new ParsedOperand
{
Type = AddressMode.Absolute,
Symbol = asm.Symtab.CreateSymbol((string)tok.Value)
});
}
}