private static void Disasm(Stream stream, uint size, TextWriter writer, Formatter formatter = null)
{
var buffer = ArrayPool <byte> .Shared.Rent((int)size);
var startPosition = stream.Position;
stream.Read(buffer, 0, (int)size);
stream.Position = startPosition;
// You can also pass in a hex string, eg. "90 91 929394", or you can use your own CodeReader
// reading data from a file or memory etc
var codeReader = new StreamCodeReader(stream, size);
var decoder = Decoder.Create(IntPtr.Size * 8, codeReader);
decoder.IP = (ulong)0;
ulong endRip = decoder.IP + (uint)size;
// This list is faster than List<Instruction> since it uses refs to the Instructions
// instead of copying them (each Instruction is 32 bytes in size). It has a ref indexer,
// and a ref iterator. Add() uses 'in' (ref readonly).
var instructions = new InstructionList();
while (decoder.IP < endRip)
{
// The method allocates an uninitialized element at the end of the list and
// returns a reference to it which is initialized by Decode().
decoder.Decode(out instructions.AllocUninitializedElement());
}
// Formatters: Masm*, Nasm* and Gas* (AT&T)
if (formatter == null)
{
formatter = new NasmFormatter();
formatter.Options.DigitSeparator = "";
formatter.Options.FirstOperandCharIndex = 10;
}
var output = new StringBuilderFormatterOutput();
// Use InstructionList's ref iterator (C# 7.3) to prevent copying 32 bytes every iteration
foreach (ref var instr in instructions)
{
// Don't use instr.ToString(), it allocates more, uses masm syntax and default options
formatter.Format(instr, output);
writer.Write($"{instr.IP:X16} ");
for (int i = 0; i < instr.ByteLength; i++)
{
writer.Write(buffer[(int)instr.IP + i].ToString("X2"));
}
writer.Write(new string(' ', 16 * 2 - instr.ByteLength * 2));
writer.WriteLine($"{output.ToStringAndReset()}");
}
}
public unsafe XrefScanner(IntPtr codeStart, int lengthLimit = 1000)
{
if (codeStart == IntPtr.Zero)
{
throw new NullReferenceException(nameof(codeStart));
}
myUnmanagedMemoryStream = new UnmanagedMemoryStream((byte *)codeStart, lengthLimit, lengthLimit, FileAccess.Read);
var codeReader = new StreamCodeReader(myUnmanagedMemoryStream);
myDecoder = Decoder.Create(IntPtr.Size * 8, codeReader);
myDecoder.IP = (ulong)codeStart;
}
private static int CalcAsmLength(Assembler asm)
{
var stream = new MemoryStream();
asm.Assemble(new StreamCodeWriter(stream), 0);
// Disassemble the result
stream.Position = 0;
var reader = new StreamCodeReader(stream);
var decoder = Decoder.Create(64, reader);
return(decoder.Select(i => i.Length).Sum());
}
internal static unsafe Decoder DecoderForAddress(IntPtr codeStart, int lengthLimit = 1000)
{
if (codeStart == IntPtr.Zero)
{
throw new NullReferenceException(nameof(codeStart));
}
var stream = new UnmanagedMemoryStream((byte *)codeStart, lengthLimit, lengthLimit, FileAccess.Read);
var codeReader = new StreamCodeReader(stream);
var decoder = Decoder.Create(IntPtr.Size * 8, codeReader);
decoder.IP = (ulong)codeStart;
return(decoder);
}
private byte[] Assemble(Assembler assembler)
{
using var stream = new MemoryStream();
assembler.Assemble(new StreamCodeWriter(stream), 0);
stream.Position = 0;
var reader = new StreamCodeReader(stream);
int next;
var bytes = new byte[stream.Length];
while ((next = reader.ReadByte()) >= 0)
{
bytes[stream.Position - 1] = (byte)next;
}
return(bytes);
}
