private void verifyBranchLength()
{
long physicalAddress = 0;
Scope parentScope = _globalScope;
foreach (var scope in parentScope.Children)
{
foreach (var instruction in scope.Statements)
{
if (instruction is CpuInstructionStatement)
{
var cpuInstruction = instruction as CpuInstructionStatement;
if (cpuInstruction.AddressingMode == CpuAddressingMode.Relative)
{
int instructionSize = (int)instruction.ComputeSize();
if (cpuInstruction.Arguments[0] is LabelInstructionArgument)
{
var labelArgument = cpuInstruction.Arguments[0] as LabelInstructionArgument;
int labelAddress = (int)scope.AddressFor(labelArgument.Label);
int branchLength = labelAddress - ((int)physicalAddress + instructionSize);
if (branchLength > sbyte.MaxValue || branchLength < sbyte.MinValue)
{
ErrorMessage error = new ErrorMessage();
error.SourceFile = SourceFilePath;
error.Message = String.Format("Branch label '{0}' is too far away. Consider reducing the distance or use a jmp.", labelArgument.Label);
error.Line = instruction.Line;
error.Column = instruction.Column;
Errors.Add(error);
}
}
}
}
physicalAddress += instruction.ComputeSize();
}
}
}