private static ImmutableDictionary <int, AstLocal> ReadLocals(MemoryScanner scanner, AstBodyBuilder bodyBuilder)
{
var map = ImmutableDictionary.CreateBuilder <int, AstLocal>();
var address = 0;
while (true)
{
var sizeByte = scanner.NextByte();
var countByte = scanner.NextByte();
if (sizeByte == 0 && countByte == 0)
{
break;
}
var size = SizeByteToValueSize(sizeByte);
// The Glulx spec states that locals will have padding to bring values
// to their natural alignment. We should account for that here. Note that
// the spec guarantees that the locals will start at a 4-byte boundary.
if (size != ValueSize.Byte && address % sizeByte != 0)
{
address += sizeByte;
}
for (int i = 0; i < countByte; i++)
{
var local = bodyBuilder.DeclareLocal(size);
map.Add(address, local);
address += sizeByte;
}
}
return(map.ToImmutable());
}
private static Operand ReadOperand(MemoryScanner scanner, byte type)
{
switch (type)
{
case 0x0: return(new Operand(OperandType.Constant, 0));
case 0x1: return(new Operand(OperandType.Constant, (uint)(sbyte)scanner.NextByte()));
case 0x2: return(new Operand(OperandType.Constant, (uint)(short)scanner.NextWord()));
case 0x3: return(new Operand(OperandType.Constant, scanner.NextDWord()));
case 0x5: return(new Operand(OperandType.Address, scanner.NextByte()));
case 0x6: return(new Operand(OperandType.Address, scanner.NextWord()));
case 0x7: return(new Operand(OperandType.Address, scanner.NextDWord()));
case 0x8: return(new Operand(OperandType.Stack, 0));
case 0x9: return(new Operand(OperandType.LocalAddress, scanner.NextByte()));
case 0xa: return(new Operand(OperandType.LocalAddress, scanner.NextWord()));
case 0xb: return(new Operand(OperandType.LocalAddress, scanner.NextDWord()));
case 0xd: return(new Operand(OperandType.RamAddress, scanner.NextByte()));
case 0xe: return(new Operand(OperandType.RamAddress, scanner.NextWord()));
case 0xf: return(new Operand(OperandType.RamAddress, scanner.NextDWord()));
default: throw new InvalidOperationException($"Invalid operand type byte: {type}");
}
}
private static FunctionKind ReadType(MemoryScanner scanner)
{
FunctionKind type;
var typeByte = scanner.NextByte();
switch (typeByte)
{
case 0xC0:
type = FunctionKind.StackArgument;
break;
case 0xC1:
type = FunctionKind.LocalArgument;
break;
default:
if (typeByte >= 0xC0 && typeByte <= 0xDF)
{
throw new InvalidOperationException($"Unknown function type: {typeByte}");
}
throw new InvalidOperationException($"Non-function: {typeByte}");
}
return(type);
}
private static uint ReadOpcodeNumber(MemoryScanner scanner)
{
var firstByte = scanner.PeekByte();
if ((firstByte & 0xC0) == 0xC0)
{
return(scanner.NextDWord() & 0x0fffffffu);
}
if ((firstByte & 0x80) == 0x80)
{
return(scanner.NextWord() & 0x3fffu);
}
return(scanner.NextByte() & 0x7fu);
}
private static (ImmutableList <Operand> loadOps, ImmutableList <Operand> storeOps) ReadOperands(MemoryScanner scanner, OpcodeDescriptor opcode)
{
var loadOpsBuilder = ImmutableList.CreateBuilder <Operand>();
var storeOpsBuilder = ImmutableList.CreateBuilder <Operand>();
var count = opcode.OperandCount;
if (count > 0)
{
var typesLength = count / 2;
if (count % 2 != 0)
{
typesLength++;
}
var dataScanner = scanner.Memory.CreateScanner(scanner.Address + typesLength);
for (int i = 0; i < count; i += 2)
{
var opsBuilder = opcode.OperandKinds[i] == OperandKind.Load
? loadOpsBuilder
: storeOpsBuilder;
var typeByte = scanner.NextByte();
var type = (byte)(typeByte & 0x0f);
var operand = ReadOperand(dataScanner, type);
opsBuilder.Add(operand);
if (i + 1 < count)
{
opsBuilder = opcode.OperandKinds[i + 1] == OperandKind.Load
? loadOpsBuilder
: storeOpsBuilder;
type = (byte)(typeByte >> 4);
operand = ReadOperand(dataScanner, type);
opsBuilder.Add(operand);
}
}
scanner.SetAddress(dataScanner.Address);
}
return(loadOpsBuilder.ToImmutable(), storeOpsBuilder.ToImmutable());
}
