/// <summary>
/// Builds an implementation method for the specified trampoline.
/// </summary>
/// <param name="trampoline">The trampoline.</param>
/// <param name="typeBuilder">The type builder for the type that will contain the method.</param>
static void BuildTrampolineMethod(Trampoline trampoline, TypeBuilder typeBuilder)
{
if (!trampoline.IsInstanceCall)
{
BuildFreeCall(trampoline, typeBuilder);
return;
}
var methodName = string.Format("CallInstance{0}", trampoline.ReturnType == typeof(void) ? string.Empty : trampoline.ReturnType.Name);
var methodBuilder = typeBuilder.DefineMethod(methodName, trampolineMethodAttributes);
var il = methodBuilder.GetILGenerator();
methodBuilder.SetSignature(trampoline.ReturnType, null, null, ExtractTypes(trampoline.ManagedParameterTypes), null, null);
methodBuilder.DefineParameter(1, ParameterAttributes.None, offsetParameterName);
methodBuilder.DefineParameter(2, ParameterAttributes.None, thisParameterName);
// Push the arguments to the native method on the stack.
for (int parameterIndex = 0; parameterIndex < trampoline.NativeParameterTypes.Count; ++parameterIndex)
{
// We use ldarg.1, ldarg.2 and ldarg.3 if possible; these opcodes are much smaller because
// they don't require an int8 parameter token (and the JIT won't inline methods over a
// certain number of bytes)
if (parameterIndex == 0)
{
il.Emit(OpCodes.Ldarg_1);
}
else if (parameterIndex == 1)
{
il.Emit(OpCodes.Ldarg_2);
}
else if (parameterIndex == 2)
{
il.Emit(OpCodes.Ldarg_3);
}
else
{
il.Emit(OpCodes.Ldarg_S, parameterIndex + 1);
}
}
// Load the instance pointer, and dereference it to leave the base address of
// the virtual table on the stack.
il.Emit(OpCodes.Ldarg_1);
il.Emit(OpCodes.Ldind_I);
// Load the byte offset from the start of the table and add them to yeild
// the pointer to the slot containing the desired method's address.
il.Emit(OpCodes.Ldarg_0);
il.Emit(OpCodes.Add);
// Read the table slot, leaving the address of the target method on the stack.
il.Emit(OpCodes.Ldind_I);
// Finally, call the method.
il.EmitCalli(OpCodes.Calli, CallingConvention.StdCall, trampoline.ReturnType, ExtractTypes(trampoline.NativeParameterTypes));
il.Emit(OpCodes.Ret);
}
static void BuildFreeCall(Trampoline trampoline, TypeBuilder typeBuilder)
{
var methodName = string.Format("CallFree{0}", trampoline.ReturnType == typeof(void) ? string.Empty : trampoline.ReturnType.Name);
var methodBuilder = typeBuilder.DefineMethod(methodName, trampolineMethodAttributes);
var il = methodBuilder.GetILGenerator();
methodBuilder.SetSignature(trampoline.ReturnType, null, null, ExtractTypes(trampoline.ManagedParameterTypes), null, null);
methodBuilder.DefineParameter(1, ParameterAttributes.None, offsetParameterName);
methodBuilder.DefineParameter(2, ParameterAttributes.None, thisParameterName);
// Push the arguments to the native method on the stack.
for (int parameterIndex = 0; parameterIndex < trampoline.NativeParameterTypes.Count; ++parameterIndex)
{
// We use ldarg.1, ldarg.2 and ldarg.3 if possible; these opcodes are much smaller because
// they don't require an int8 parameter token (and the JIT won't inline methods over a
// certain number of bytes)
if (parameterIndex == 0)
il.Emit(OpCodes.Ldarg_1);
else if (parameterIndex == 1)
il.Emit(OpCodes.Ldarg_2);
else if (parameterIndex == 2)
il.Emit(OpCodes.Ldarg_3);
else
il.Emit(OpCodes.Ldarg_S, parameterIndex + 1);
}
// Load the instance pointer, and dereference it to leave the base address of
// the virtual table on the stack.
//il.Emit(OpCodes.Ldarg_1);
//il.Emit(OpCodes.Ldind_I);
//// Load the byte offset from the start of the table and add them to yeild
//// the pointer to the slot containing the desired method's address.
// For free functions, the offset is the actual entry point.
il.Emit(OpCodes.Ldarg_0);
//il.Emit(OpCodes.Add);
// Read the table slot, leaving the address of the target method on the stack.
//il.Emit(OpCodes.Ldind_I);
// Finally, call the method.
il.EmitCalli(OpCodes.Calli, CallingConvention.StdCall, trampoline.ReturnType, ExtractTypes(trampoline.NativeParameterTypes));
il.Emit(OpCodes.Ret);
}
/// <summary>
/// Adds a trampoline to the builder.
/// </summary>
/// <param name="trampoline">The trampoline to add.</param>
public void Add(Trampoline trampoline)
{
trampolines.Add(trampoline);
}
/// <summary>
/// Adds a trampoline to the builder.
/// </summary>
/// <param name="trampoline">The trampoline to add.</param>
public void Add(Trampoline trampoline)
{
trampolines.Add(trampoline);
}
