private OpCode OpcodeFromInstruction(AtlasParser.InstructionContext context)
{
AtlasParser.InstructionCodeContext instructionCode = context.instructionCode();
AtlasParser.InstructionCodeNeedsArgContext instructionNeedsArgumentCode = context.instructionCodeNeedsArg();
string s = instructionCode != null?instructionCode.GetText() : (instructionNeedsArgumentCode != null ? instructionNeedsArgumentCode.GetText() : "MISSINGINSTRUCTIONERROR");
return(OpcodeFromString(s));
}
public override void ExitInstruction(AtlasParser.InstructionContext context)
{
OpCode opCode = OpcodeFromInstruction(context);
int argSize = AtlasCPU.ArgSizeFromOpCode(opCode);
bool needsArg = argSize != 0;
if (m_currentPass == AssemblerSemanticAnalysisPass.RecordLabels)
{
//space for opcode
m_fileSize++;
//does this instruction take an argument?
if (!needsArg)
{
return;
}
//space for arg
m_fileSize += argSize;
}
else if (m_currentPass == AssemblerSemanticAnalysisPass.CodeGen)
{
EmitOpCode(opCode);
//does this instruction take an argument?
if (!needsArg)
{
return;
}
//if it does, emit that value
int argVal = 0;
//argument is a label
if (context.ID() != null)
{
//check that the label exists
if (!m_labels.ContainsKey(context.ID().Symbol.Text))
{
SematicError(context, "Label " + context.ID().GetText() + " is undefined");
}
argVal = m_labels[context.ID().Symbol.Text];
}
//argument is a literal
else if (context.literal() != null)
{
argVal = GetLiteralValue(context.literal());
}
EmitWord(argVal);
}
}
