chrissx

Probably pointless, but could useful depending on the individual who is interested in IL programming and this snippet is about 140 lines of code. I created it on a whim.
 
The purpose of this snippet is basically to emit Brainf*ck programming language into IL during runtime in C#:
 
using System; using System.Collections.Generic; using System.Reflection.Emit; using System.Runtime.InteropServices; using System.IO; namespace BFJIT { public unsafe class BFJIT { public static void ZeroOutMemory(byte* ptr, int size) { for (int I = 0; I < size; I++) ptr[I] = 0; } public delegate IntPtr BrainFkCompile(); public BrainFkCompile Compile(string code) { var WhileBeginMarkStack = new Stack<Label>(); var WhileEndMarkStack = new Stack<Label>(); var reader = new StringReader(code); var method = new DynamicMethod($"BrainFk{Guid.NewGuid().ToString().Replace("-", "_")}", typeof(IntPtr), null); var il = method.GetILGenerator(); // Set the locals il.DeclareLocal(typeof(byte*)); il.DeclareLocal(typeof(IntPtr)); // Allocate pointer il.Emit(OpCodes.Ldc_I4, 1048576); // 1 MB Memory il.EmitCall(OpCodes.Call, typeof(Marshal).GetMethod("AllocHGlobal", new Type[] { typeof(int) }), null); il.Emit(OpCodes.Stloc_1); il.Emit(OpCodes.Ldloca_S, 1); il.EmitCall(OpCodes.Call, typeof(IntPtr).GetMethod("ToPointer"), null); il.Emit(OpCodes.Stloc_0); il.Emit(OpCodes.Ldloc_0); il.Emit(OpCodes.Ldc_I4, 1048576); // 1 MB Memory il.EmitCall(OpCodes.Call, typeof(BFJIT).GetMethod("ZeroOutMemory"), null); int currentCharacter = -1; do { currentCharacter = reader.Read(); switch ((char)currentCharacter) { case '>': { il.Emit(OpCodes.Ldloc_0); il.Emit(OpCodes.Ldc_I4_1); il.Emit(OpCodes.Add); il.Emit(OpCodes.Stloc_0); break; } case '<': { il.Emit(OpCodes.Ldloc_0); il.Emit(OpCodes.Ldc_I4_1); il.Emit(OpCodes.Sub); il.Emit(OpCodes.Stloc_0); break; } case '+': { il.Emit(OpCodes.Ldloc_0); il.Emit(OpCodes.Dup); il.Emit(OpCodes.Ldind_U1); int increment = 1; while (reader.Peek() == '+') { ++increment; reader.Read(); } il.Emit(OpCodes.Ldc_I4, increment); il.Emit(OpCodes.Add); il.Emit(OpCodes.Conv_U1); il.Emit(OpCodes.Stind_I1); break; } case '-': { il.Emit(OpCodes.Ldloc_0); il.Emit(OpCodes.Dup); il.Emit(OpCodes.Ldind_U1); int decrement = 1; while (reader.Peek() == '-') { ++decrement; reader.Read(); } il.Emit(OpCodes.Ldc_I4, decrement); il.Emit(OpCodes.Sub); il.Emit(OpCodes.Conv_U1); il.Emit(OpCodes.Stind_I1); break; } case '.': { il.Emit(OpCodes.Ldloc_0); il.Emit(OpCodes.Ldind_U1); il.EmitCall(OpCodes.Call, typeof(Console).GetMethod("Write", new[] { typeof(byte) }), null); break; } case '[': { Label begin = il.DefineLabel(); Label end = il.DefineLabel(); il.Emit(OpCodes.Br, end); il.MarkLabel(begin); WhileBeginMarkStack.Push(begin); WhileEndMarkStack.Push(end); break; } case ']': { il.MarkLabel(WhileEndMarkStack.Pop()); il.Emit(OpCodes.Ldloc_0); il.Emit(OpCodes.Ldind_U1); il.Emit(OpCodes.Brtrue, WhileBeginMarkStack.Pop()); break; } default: continue; } } while (currentCharacter > -1); il.Emit(OpCodes.Ldloc_1); il.Emit(OpCodes.Ret); return (BrainFkCompile)method.CreateDelegate(typeof(BrainFkCompile)); } static unsafe void Main(string[] args) { var jitter = new BFJIT(); var func = jitter.Compile("++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>.>---.+++++++..+++.>>.<-.<.+++.------.--------.>>+.>++."); Console.WriteLine("Brainfk Compiled"); var ptr = func(); Console.WriteLine(); Console.WriteLine("Program Terminated."); Marshal.FreeHGlobal(ptr); Console.ReadLine(); } } }