public static void SUBN(JITContext ctx, Disassembler.DecompEntry inst, ILGenerator gen)
{
Label CaseNotOverflow = gen.DefineLabel();
Label Continue = gen.DefineLabel();
gen.EmitGetRegister(inst.Value.Reg0, ctx);
gen.EmitGetRegister(inst.Value.Reg1, ctx);
gen.Emit(OpCodes.Ldind_I1);
gen.Emit(OpCodes.Conv_U1);
gen.EmitGetRegister(inst.Value.Reg0, ctx);
gen.Emit(OpCodes.Ldind_I1);
gen.Emit(OpCodes.Conv_U1);
gen.Emit(OpCodes.Sub);
//now the stack contains the difference and the register address
gen.Emit(OpCodes.Dup);
gen.Emit(OpCodes.Ldc_I4_M1);
gen.Emit(OpCodes.Bgt, CaseNotOverflow);
//CaseOverflow
gen.EmitGetRegister(0xF, ctx);
gen.Emit(OpCodes.Ldc_I4, 0);
gen.Emit(OpCodes.Br, Continue);
gen.MarkLabel(CaseNotOverflow);
gen.EmitGetRegister(0xF, ctx);
gen.Emit(OpCodes.Ldc_I4, 1);
//Assign value to VF and store sum
gen.MarkLabel(Continue);
gen.Emit(OpCodes.Stind_I1); //Store the VF value that's on the stack
gen.Emit(OpCodes.Conv_U1); //Store the difference
gen.Emit(OpCodes.Stind_I1);
}
public static void LRI(JITContext ctx, Disassembler.DecompEntry inst, ILGenerator gen)
{
gen.Emit(OpCodes.Ldarg_0);
gen.Emit(OpCodes.Ldc_I4, inst.Value.Immediate16);
//gen.Emit(OpCodes.Conv_I2);
gen.Emit(OpCodes.Call, ctx.RegisterI.SetMethod);
}
public static void XOR(JITContext ctx, Disassembler.DecompEntry inst, ILGenerator gen)
{
gen.EmitPushRegistersAndIndirectTarget(inst.Value.Reg0, inst.Value.Reg1, ctx);
gen.Emit(OpCodes.Xor);
gen.Emit(OpCodes.Conv_U1);
gen.Emit(OpCodes.Stind_I1);
}
public static void SHL(JITContext ctx, Disassembler.DecompEntry inst, ILGenerator gen)
{
Label Continue = gen.DefineLabel();
Label HighBitNotSet = gen.DefineLabel();
gen.EmitGetRegister(inst.Value.Reg0, ctx);
gen.Emit(OpCodes.Dup); //Duplicate address for loading
gen.Emit(OpCodes.Ldind_U1); //Load value
gen.Emit(OpCodes.Dup); //duplicate value for VF comparison
gen.Emit(OpCodes.Stloc_0); //Store for VF comparison
gen.Emit(OpCodes.Ldc_I4_1);
gen.Emit(OpCodes.Shl); //Shift and store
gen.Emit(OpCodes.Stind_I1);
gen.Emit(OpCodes.Ldloc_0);
gen.Emit(OpCodes.Ldc_I4, 0x80);
gen.Emit(OpCodes.And);
gen.Emit(OpCodes.Ldc_I4_0);
gen.Emit(OpCodes.Beq, HighBitNotSet);
//HighBitSet:
gen.EmitGetRegister(0xF, ctx);
gen.Emit(OpCodes.Ldc_I4_1);
gen.Emit(OpCodes.Br, Continue);
//Not set
gen.MarkLabel(HighBitNotSet);
gen.EmitGetRegister(0xF, ctx);
gen.Emit(OpCodes.Ldc_I4_0);
gen.MarkLabel(Continue);
gen.Emit(OpCodes.Stind_I1);
}
public static void ADD(JITContext ctx, Disassembler.DecompEntry inst, ILGenerator gen)
{
Label CaseNotOverflow = gen.DefineLabel();
Label Continue = gen.DefineLabel();
gen.EmitPushRegistersAndIndirectTarget(inst.Value.Reg0, inst.Value.Reg1, ctx);
gen.Emit(OpCodes.Add);
//now the stack contains the sum and the register address
gen.Emit(OpCodes.Dup); //Duplicate the sum for comparison
gen.Emit(OpCodes.Ldc_I4, 0xFF);
gen.Emit(OpCodes.Ble, CaseNotOverflow); //If greater goto case overflow
//else CaseOverflow:
gen.EmitGetRegister(0xF, ctx); //Push VF register addres for storing the overflow bit
gen.Emit(OpCodes.Ldc_I4, 1);
gen.Emit(OpCodes.Br, Continue);
//CaseNotOverflow:
gen.MarkLabel(CaseNotOverflow);
gen.EmitGetRegister(0xF, ctx); //Push VF register addres for storing the overflow bit
gen.Emit(OpCodes.Ldc_I4, 0);
//Assign value to VF and store sum
gen.MarkLabel(Continue);
gen.Emit(OpCodes.Stind_I1); //Store the VF value that's on the stack
gen.Emit(OpCodes.Conv_U1); //Store the sum value we duplicated earlier
gen.Emit(OpCodes.Stind_I1);
}
public static void LD(JITContext ctx, Disassembler.DecompEntry inst, ILGenerator gen)
{
gen.EmitGetRegister(inst.Value.Reg0, ctx); //Push target address
gen.EmitGetRegister(inst.Value.Reg1, ctx); //Push source address
gen.Emit(OpCodes.Ldind_U1); //Pop source address, push value
gen.Emit(OpCodes.Stind_I1); //assign value
}
public static void SDT(JITContext ctx, Disassembler.DecompEntry inst, ILGenerator gen)
{
gen.EmitGetRegister(inst.Value.Reg0, ctx);
gen.Emit(OpCodes.Ldarg_0);
gen.Emit(OpCodes.Call, ctx.RegisterDT.GetMethod);
gen.Emit(OpCodes.Stind_I1);
}
public static void IN(JITContext ctx, Disassembler.DecompEntry inst, ILGenerator gen)
{
Debug.WriteLine("WARN: Unimplemented input instruction");
//Wait for a key press, store the value of the key in Vx.
gen.EmitGetRegister(inst.Value.Reg0, ctx);
gen.Emit(OpCodes.Ldc_I4_0);
gen.Emit(OpCodes.Stind_I1);
}
public static void SEI(JITContext ctx, Disassembler.DecompEntry inst, ILGenerator gen)
{
gen.EmitGetRegister(inst.Value.Reg0, ctx);
gen.Emit(OpCodes.Ldind_I1);
gen.Emit(OpCodes.Conv_U1);
gen.EmitLoadImmediate(inst);
gen.Emit(OpCodes.Beq, ctx.Label(inst.Offset + 4));
}
public static void CLS(JITContext ctx, Disassembler.DecompEntry inst, ILGenerator gen)
{
var method = typeof(Interpreter.Implementation).GetMethod(nameof(Implementation.CLS));
//Args are: Chip8State state
gen.Emit(OpCodes.Ldarg_0);
gen.Emit(OpCodes.Call, method);
}
public static void STBCD(JITContext ctx, Disassembler.DecompEntry inst, ILGenerator gen)
{
var method = typeof(Interpreter.Implementation).GetMethod(nameof(Implementation.STBCD));
//Args are: Chip8State state, ref byte regx
gen.Emit(OpCodes.Ldarg_0);
gen.EmitGetRegister(inst.Value.Reg0, ctx);
gen.Emit(OpCodes.Call, method);
}
public static void LDREG(JITContext ctx, Disassembler.DecompEntry inst, ILGenerator gen)
{
var method = typeof(Interpreter.Implementation).GetMethod(nameof(Implementation.LDREG));
//Args are: Chip8State state, byte regx
gen.Emit(OpCodes.Ldarg_0);
gen.Emit(OpCodes.Ldc_I4_S, inst.Value.Reg0);
gen.Emit(OpCodes.Call, method);
}
public static void ADDI(JITContext ctx, Disassembler.DecompEntry inst, ILGenerator gen)
{
gen.EmitGetRegister(inst.Value.Reg0, ctx);
gen.Emit(OpCodes.Dup);
gen.Emit(OpCodes.Ldind_U1);
gen.EmitLoadImmediate(inst);
gen.Emit(OpCodes.Add);
gen.Emit(OpCodes.Conv_U1);
gen.Emit(OpCodes.Stind_I1);
}
public static void SNER(JITContext ctx, Disassembler.DecompEntry inst, ILGenerator gen)
{
gen.EmitGetRegister(inst.Value.Reg0, ctx);
gen.Emit(OpCodes.Ldind_I1);
gen.Emit(OpCodes.Conv_U1);
gen.EmitGetRegister(inst.Value.Reg1, ctx);
gen.Emit(OpCodes.Ldind_I1);
gen.Emit(OpCodes.Conv_U1);
gen.Emit(OpCodes.Bne_Un, ctx.Label(inst.Offset + 4));
}
public static void JMP(JITContext ctx, Disassembler.DecompEntry inst, ILGenerator gen)
{
if (inst.Instr.Value.Immediate16 == inst.Offset)
{
gen.Emit(OpCodes.Ret);
}
else
{
gen.Emit(OpCodes.Br, ctx.Labels[inst.Value.Immediate16]);
}
}
public static void ADDRI(JITContext ctx, Disassembler.DecompEntry inst, ILGenerator gen)
{
gen.Emit(OpCodes.Ldarg_0); //reference for the last store call
gen.EmitGetRegister(inst.Value.Reg0, ctx);
gen.Emit(OpCodes.Ldind_I1);
gen.Emit(OpCodes.Conv_U1);
gen.Emit(OpCodes.Ldarg_0);
gen.Emit(OpCodes.Call, ctx.RegisterI.GetMethod);
gen.Emit(OpCodes.Add);
gen.Emit(OpCodes.Call, ctx.RegisterI.SetMethod);
}
public static void DRW(JITContext ctx, Disassembler.DecompEntry inst, ILGenerator gen)
{
var method = typeof(Interpreter.Implementation).GetMethod(nameof(Implementation.DRW));
//Args are: Chip8State state, ref byte regx, ref byte regy, byte imm4
gen.Emit(OpCodes.Ldarg_0);
gen.EmitGetRegister(inst.Value.Reg0, ctx);
gen.EmitGetRegister(inst.Value.Reg1, ctx);
gen.Emit(OpCodes.Ldc_I4_S, inst.Value.Immediate4);
gen.Emit(OpCodes.Call, method);
}
private (DynamicMethod, ILGenerator) CreateMethod(string name, JITContext ctx)
{
DynamicMethod res = (DynamicMethod)(object)new DynamicMethod(name, typeof(void), new[]
{
typeof(Chip8State),
typeof(Registers).MakeByRefType()
});
ILGenerator gen = res.GetILGenerator();
gen.DeclareLocal(typeof(int));
return(res, gen);
}
public static void JMP0(JITContext ctx, Disassembler.DecompEntry inst, ILGenerator gen)
{
List <Label> JumpTable = new List <Label>();
for (int i = inst.Value.Immediate16; i < inst.Value.Immediate16 + 256; i++)
{
JumpTable.Add(ctx.Label(i));
}
gen.EmitGetRegister(0, ctx);
gen.Emit(OpCodes.Ldind_I1);
gen.Emit(OpCodes.Conv_U1);
gen.Emit(OpCodes.Switch, JumpTable.ToArray());
}
public JITROMDelegate JITROM(Span <byte> ROM, SortedSet <UInt16> BreakPoints = null)
{
if (BreakPoints == null)
{
BreakPoints = new SortedSet <ushort>();
}
var exe = disasm.DisassembleProgram(ROM);
JITContext ctx = new JITContext
{
BreakPoints = BreakPoints,
Disasm = exe
};
var(res, gen) = CreateMethod("JITROM", ctx);
//Find all function calls
Dictionary <UInt16, TranslatedFunction> Functions = exe.Entries.Where(x => !x.IsData && x.Instr.Value.Instruction == Instruction.CALL)
.Select(x => x.Instr.Value.Immediate16)
.Distinct()
.ToDictionary(x => x, x => (TranslatedFunction)null);
//Function calls will get translated to their own method to use the runtime call stack
foreach (var f in Functions.Keys.ToArray())
{
var(tmpMethod, TmpGen) = CreateMethod("method_" + f.ToString("X4"), ctx);
Functions[f] = new TranslatedFunction
{
Method = tmpMethod,
Generator = TmpGen,
Info = tmpMethod
};
}
ctx.Functions = Functions;
//As detecting where a funnction ends is not trivial we're just going to JIT all functions to the end of the rom, disgusting i know
foreach (var f in Functions.Keys.Where(x => x >= Chip8State.ProgramStart))
{
JITBlock(Functions[f].Generator, ctx, (f - Chip8State.ProgramStart) / 2, exe.Entries.Length);
}
//Then JIT the whole ROM
JITBlock(gen, ctx, 0, exe.Entries.Length);
return((JITROMDelegate)res.CreateDelegate(typeof(JITROMDelegate)));
}
public static void SHR(JITContext ctx, Disassembler.DecompEntry inst, ILGenerator gen)
{
gen.EmitGetRegister(inst.Value.Reg0, ctx);
gen.Emit(OpCodes.Dup); //Duplicate address for loading
gen.Emit(OpCodes.Ldind_U1); //Load value
gen.Emit(OpCodes.Dup); //duplicate value for VF comparison
gen.Emit(OpCodes.Stloc_0); //Store for VF comparison
gen.Emit(OpCodes.Ldc_I4_1);
gen.Emit(OpCodes.Shr_Un); //Shift and store
gen.Emit(OpCodes.Stind_I1);
gen.EmitGetRegister(0xF, ctx);
gen.Emit(OpCodes.Ldloc_0);
gen.Emit(OpCodes.Ldc_I4_1);
gen.Emit(OpCodes.And);
gen.Emit(OpCodes.Stind_I1);
}
public static void RET(JITContext ctx, Disassembler.DecompEntry inst, ILGenerator gen)
{
gen.Emit(OpCodes.Ret);
}
/// <summary>
/// Pushes the address of the N register on the stack
/// </summary>
internal static void EmitGetRegister(this ILGenerator gen, int N, JITContext ctx)
{
gen.Emit(OpCodes.Ldarg_1);
gen.Emit(OpCodes.Ldflda, Registers.Fields[N]);
}
public static void SYS(JITContext ctx, Disassembler.DecompEntry inst, ILGenerator gen)
{
Debug.WriteLine("WARN: Sys called");
}
public static void CALL(JITContext ctx, Disassembler.DecompEntry inst, ILGenerator gen)
{
gen.Emit(OpCodes.Ldarg_0);
gen.Emit(OpCodes.Ldarg_1);
gen.Emit(OpCodes.Call, ctx.Functions[inst.Value.Immediate16].Method);
}
public static void SKNP(JITContext ctx, Disassembler.DecompEntry inst, ILGenerator gen)
{
Debug.WriteLine("WARN: Unimplemented input instruction");
//Skip next instruction if key with the value of Vx is pressed.
}
/// <summary>
/// After the code emitted by this method the managed stack looks like:
///
/// <br>--bottom--</br>
/// <br>target register address</br>
/// <br>target value </br>
/// <br>source value </br>
///
/// </summary>
/// <param name="target">target register index</param>
/// <param name="source">source register index</param>
/// <param name="ctx">state ctx</param>
internal static void EmitPushRegistersAndIndirectTarget(this ILGenerator gen, int target, int source, JITContext ctx)
{
gen.EmitGetRegister(target, ctx);
gen.Emit(OpCodes.Dup);
gen.Emit(OpCodes.Ldind_U1);
gen.EmitGetRegister(source, ctx);
gen.Emit(OpCodes.Ldind_U1);
}
void JITBlock(ILGenerator gen, JITContext ctx, int start, int end)
{
//Every function has its own set of labels
ctx.Labels = new Dictionary <ushort, Label>();
void AddLabel(int v)
{
//Is this offset outside of the ROM ? Sometimes data can be misinterpreted as code
if (v < Chip8State.ProgramStart)
{
return;
}
//Are we trying to jump from a function to code outside of it ?
if ((v - Chip8State.ProgramStart) / 2 < start)
{
Debugger.Break();
}
if (!ctx.Labels.ContainsKey((UInt16)v))
{
ctx.Labels.Add((UInt16)v, gen.DefineLabel());
}
}
//Calculate all the labels we need beforehand
for (int i = start; i < end; i++)
{
var entry = ctx.Disasm.Entries[i];
if (entry.IsData)
{
continue;
}
if (!entry.Value.IsControlFlow() || entry.Instruction == Instruction.RET)
{
continue;
}
if (entry.Value.IsSkipNext())
{
AddLabel(entry.Offset + 4);
}
else if (entry.Value.IsJumpStatic())
{
AddLabel(entry.Value.Immediate16);
}
else if (entry.Instr.Value.IsJumpVariable())
{
/*
* The JMP0 instruction jumps to immediate value + V0
* The optimal way to implement this would be hooking jumps and JIT based on the address...
* ...Or we can bruteforce all 256 cases by using a jumptable with the MSIL "switch" instruction
*/
for (int j = entry.Value.Immediate16; j < entry.Instr.Value.Immediate16 + 256; j++)
{
AddLabel(j);
}
}
else
{
throw new Exception("Invalid jump instruction");
}
}
SortedSet <UInt16> MarkedLabels = new SortedSet <ushort>();
for (int i = start; i < end; i++)
{
var entry = ctx.Disasm.Entries[i];
if (entry.IsData)
{
continue;
}
var instr = entry.Instr.Value.Instruction;
//This is not really useful as visual studio can't debug "Lightweight functions"
if (ctx.BreakPoints.Contains(entry.Offset))
{
gen.Emit(OpCodes.Break);
}
//Mark labels as we go
if (ctx.Labels.ContainsKey(entry.Offset))
{
gen.MarkLabel(ctx.Labels[entry.Offset]);
MarkedLabels.Add(entry.Offset);
}
LinkEmitters[instr](ctx, entry, gen);
}
//Set all other labels to end of the fnction
foreach (var lbl in ctx.Labels)
{
if (!MarkedLabels.Contains(lbl.Key))
{
gen.MarkLabel(lbl.Value);
}
}
gen.Emit(OpCodes.Ret);
}