using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using Iced.Intel;
using static Iced.Intel.AssemblerRegisters;

var asm = new Assembler(64);

var msgHello = asm.CreateLabel();

asm.push(rbp);
asm.mov(rbp, rsp);

asm.push(rsi);
asm.push(rdi);

asm.push(r15);
asm.push(r14);


// label address to register --- mov rcx, msgHello
asm.lea(rcx, __[msgHello]);
asm.call((ulong)typeof(Test).GetMethod(nameof(Test.UnsafeWriteCString))!.MethodHandle.GetFunctionPointer());



asm.pop(r14);
asm.pop(r15);

asm.pop(rdi);
asm.pop(rsi);

asm.mov(rsp, rbp);
asm.pop(rbp);
asm.ret();

asm.Label(ref msgHello);
asm.db("Hello, World!\n\r\0"u8);

unsafe
{
    var func = AsmExecutor.MakeFunction<long>(asm);

    Console.WriteLine(func());
    Console.WriteLine("Hi");
}

public class Test
{
    [MethodImpl(MethodImplOptions.AggressiveOptimization)]
    public static unsafe void UnsafeWriteCString(byte* ptr)
    {
        while (*ptr != '\0')
        {
            Console.Write((char)*ptr);
            ptr++;
        }
    }
}


public static partial class AsmExecutor
{
    private const uint PageExecuteReadwrite = 0x40;
    private const uint MemCommit = 0x1000;

    [LibraryImport("kernel32.dll", SetLastError = true)]
    private static partial IntPtr VirtualAlloc(IntPtr lpAddress, uint dwSize, uint flAllocationType, uint flProtect);

    public static unsafe delegate*<T> MakeFunction<T>(Assembler asm)
    {
        const ulong rip = 0x10;
        var stream = new MemoryStream();
        asm.Assemble(new StreamCodeWriter(stream), rip);

        var ptr = VirtualAlloc(IntPtr.Zero, (uint)stream.Length, MemCommit, PageExecuteReadwrite);
        Marshal.Copy(stream.ToArray(), 0, ptr, (int)stream.Length);

        return (delegate*<T>)ptr;
    }
}