public void Link()
{
mUnits.Clear();
mInstructions.Clear();
mData.Clear();
mLit.Clear();
mBss = 0;
mAllSymbols.Clear();
mSymbolUsages.Clear();
//Placeholder for calling main
//mInstructions.Add(new Instruction(OpCode.NOOPERATION));
//mInstructions.Add(new Instruction(OpCode.HALT));//After main returns, HALT
foreach (string file in mInputFiles)
{
CompilationUnit unit = new CompilationUnit();
bool success = unit.Open(file);
if (success)
{
unit.InstructionOffset = mInstructions.Count;
unit.DataOffset = mData.Count;
unit.LitOffset = mLit.Count;
foreach (var i in unit.Instructions)
{
mInstructions.Add(i);
}
foreach (var b in unit.Data)
{
mData.Add(b);
}
foreach (var b in unit.Lit)
{
mLit.Add(b);
}
mBss += (int)unit.Header.BssSize;
mUnits.Add(unit);
}
}
TotalInstructionCount = mInstructions.Count;
TotalDataBytes = mData.Count;
TotalLitBytes = mLit.Count;
//Resolve internal symbols (after this, data and instructions will be modified in the unit)
foreach (var unit in mUnits)
{
unit.ResolveSymbols();
}
mInstructions.Clear();
mData.Clear();
mLit.Clear();
foreach (var unit in mUnits)
{
foreach (var i in unit.Instructions)
{
mInstructions.Add(i);
}
foreach (var b in unit.Data)
{
mData.Add(b);
}
foreach (var b in unit.Lit)
{
mLit.Add(b);
}
}
foreach (var unit in mUnits)
{
foreach (var s in unit.Symbols)
{
if (s.Flag == Symbol.EnFlag.Export)
{
if (mAllSymbols.ContainsKey(s.Name))
{
throw new Exception(string.Format("Symbol '{0}' in {1} is already defined in {2}", s.Name, unit.File, mAllSymbols[s.Name].Value.File));
}
else
{
mAllSymbols.Add(s.Name, new KeyValuePair <Symbol, CompilationUnit>(s, unit));
}
}
}
}
ResolveExternals();
//save data and lit symbol usage addresses (including internals) here in order for machine to adjust addresses in runtime
int symbolId = 0;
foreach (var unit in mUnits)
{
foreach (SymbolUsage su in unit.SymbolUsages)
{
//At this stage, symbol name is not important
int address = su.Address;
switch (su.Section)
{
case EnSection.Code:
address += unit.InstructionOffset;
break;
case EnSection.Data:
address += unit.DataOffset;
break;
}
SymbolUsage newSu = new SymbolUsage((++symbolId).ToString(), su.Section, address);
mSymbolUsages.Add(newSu);
}
}
/*
* Symbol symbolMain = null;
* foreach (var unit in mUnits)
* {
* symbolMain = unit.GetSymbol("main");
* if (null != symbolMain)
* {
* if (symbolMain.Section == EnSection.Code)
* {
* mInstructions[0].Operation = OpCode.CALL;
* mInstructions[0].Modifier1 = (UInt16)(OpModifier.Immediate | OpModifier.Absolute);
* mInstructions[0].Parameter1 = (symbolMain.Address + unit.InstructionOffset) * Instruction.InstructionSize;
* }
* else
* {
* throw new Exception("main function not found!");
* }
* break;
* }
* }
* if (null == symbolMain)
* {
* throw new Exception("main() could not be found!");
* }*/
}
//May have errors
void ResolveExternals()
{
foreach (var unit in mUnits)
{
foreach (var symbolUsage in unit.UnresolvedSymbols)
{
if (mAllSymbols.ContainsKey(symbolUsage.Name))
{
var symbolAndUnit = mAllSymbols[symbolUsage.Name];
Symbol symbol = symbolAndUnit.Key;
CompilationUnit symbolOwnerUnit = symbolAndUnit.Value;
switch (symbolUsage.Section)
{
case EnSection.Code:
{
int address = -1;
switch (symbol.Section)
{
case EnSection.Code:
address = (symbol.Address + symbolOwnerUnit.InstructionOffset) * Instruction.InstructionSize;
break;
case EnSection.Data:
address = symbolOwnerUnit.DataOffset + symbol.Address + Instruction.InstructionSize * Linker.TotalInstructionCount;
break;
}
if (address >= 0)
{
mInstructions[unit.InstructionOffset + symbolUsage.Address].Parameter1 = address;
}
else
{
throw new Exception(string.Format("Symbol location not found: {0}", symbol.Name));
}
}
break;
case EnSection.Data:
{
int address = symbol.Address + symbolOwnerUnit.LitOffset + Linker.TotalDataBytes + Instruction.InstructionSize * Linker.TotalInstructionCount;
byte[] bytes = BitConverter.GetBytes(address);
mData[unit.DataOffset + symbolUsage.Address + 0] = bytes[0];
mData[unit.DataOffset + symbolUsage.Address + 1] = bytes[1];
mData[unit.DataOffset + symbolUsage.Address + 2] = bytes[2];
mData[unit.DataOffset + symbolUsage.Address + 3] = bytes[3];
}
break;
default:
throw new Exception(string.Format("Symbol section not found: {0}", symbol.Name));
}
}
else
{
throw new Exception(string.Format("Unresolved symbol '{0}' used in {1}", symbolUsage.Name, unit.File));
}
}
}
}