本篇讲解怎么加载和保存参数，以及参数起始序号的确定。
参数的加载
加载参数的指令是Ldarg、Ldarg_S、Ldarg_0、Ldarg_1、Ldarg_2、Ldarg_3。
Ldarg_0是加载第0个参数，例子 ilGenerator.Emit(OpCodes.Ldarg_0);
Ldarg_1是加载第1个参数，例子 ilGenerator.Emit(OpCodes.Ldarg_1);
Ldarg_2是加载第2个参数，例子 ilGenerator.Emit(OpCodes.Ldarg_2);
Ldarg_3是加载第3个参数，例子 ilGenerator.Emit(OpCodes.Ldarg_3);
Ldarg_S是加载次序为0到255的参数，例子 ilGenerator.Emit(OpCodes.Ldarg_S,5);
Ldarg加载任意次序的参数,例子 ilGenerator.Emit(OpCodes.Ldarg,6)。
我们可以根据指令的说明实现一个方便调用的方法，源码如下
public static void LoadArg(ILGenerator ilGenerator, int argIndex)
{
switch (argIndex)
{
case :
ilGenerator.Emit(OpCodes.Ldarg_0);
return;
case :
ilGenerator.Emit(OpCodes.Ldarg_1);
return;
case :
ilGenerator.Emit(OpCodes.Ldarg_2);
return;
case :
ilGenerator.Emit(OpCodes.Ldarg_3);
return;
}
if (argIndex > && argIndex <= )
{
ilGenerator.Emit(OpCodes.Ldarg_S, argIndex);
return;
}
else
{
ilGenerator.Emit(OpCodes.Ldarg, argIndex);
return;
}
}
参数的保存
保存参数的指令是Starg、Starg_S
Ldarg_S是保存次序为0到255的参数，例子 ilGenerator.Emit(OpCodes.Starg_S,1);
Starg加载任意次序的参数,例子 ilGenerator.Emit(OpCodes.Starg,6)。
我们可以根据指令的说明实现一个方便调用的方法，源码如下
public static void StormArg(ILGenerator ilGenerator, int argIndex)
{
if (argIndex > 0 && argIndex <= 255)
{
ilGenerator.Emit(OpCodes.Starg_S, argIndex);
return;
}
else
{
ilGenerator.Emit(OpCodes.Starg, argIndex);
return;
}
}
参数起始序号的确定
参数的起始序号不一定从0开始，也可能从1开始，这是由方法是否是static决定的。
如果参数所在的方法是static修饰的，序号从0开始；
如果不是static修饰，则从0开始。
完整的一个例子如下
using System;
using System.Reflection;
using System.Reflection.Emit;namespace LX1_ILDemo
{
class Demo08_Arg
{
static string binaryName = "Demo08_Arg.exe";
static string namespaceName = "LX1_ILDemo";
static string typeName = "ArgTest"; static AssemblyBuilder assemblyBuilder;
static ModuleBuilder moduleBuilder;
static TypeBuilder typeBuilder;
static MethodBuilder mainMethod;
static MethodBuilder printStaticMethod;
static MethodBuilder printInstaceMethod;
static ConstructorBuilder constructorBuilder; static void Emit_PrintInstace()
{
printInstaceMethod = typeBuilder.DefineMethod("PrintInstanceArg", MethodAttributes.Public,
typeof(void), new Type[] { typeof(int), typeof(int), typeof(int), typeof(int), typeof(string) });
ILGenerator printILInstaceGenerator = printInstaceMethod.GetILGenerator();
ParameterBuilder ab1 = printStaticMethod.DefineParameter(, ParameterAttributes.None, "i1");
ParameterBuilder ab2 = printStaticMethod.DefineParameter(, ParameterAttributes.None, "i2");
ParameterBuilder ab3 = printStaticMethod.DefineParameter(, ParameterAttributes.None, "i3");
ParameterBuilder ab4 = printStaticMethod.DefineParameter(, ParameterAttributes.None, "i4");
ParameterBuilder ab5 = printStaticMethod.DefineParameter(, ParameterAttributes.None, "s5"); MethodInfo writeIntLineMethod = typeof(Console).GetMethod("WriteLine", new Type[] { typeof(int) });
MethodInfo writeStringLineMethod = typeof(Console).GetMethod("WriteLine", new Type[] { typeof(string) });
LoadArg(printILInstaceGenerator,);
printILInstaceGenerator.Emit(OpCodes.Call, writeIntLineMethod);
LoadArg(printILInstaceGenerator, );
printILInstaceGenerator.Emit(OpCodes.Call, writeIntLineMethod);
LoadArg(printILInstaceGenerator, );
printILInstaceGenerator.Emit(OpCodes.Call, writeIntLineMethod);
LoadArg(printILInstaceGenerator, );
printILInstaceGenerator.Emit(OpCodes.Call, writeIntLineMethod);
LoadArg(printILInstaceGenerator, );
printILInstaceGenerator.Emit(OpCodes.Call, writeStringLineMethod);
printILInstaceGenerator.Emit(OpCodes.Ldstr, "world");
StormArg(printILInstaceGenerator, );
LoadArg(printILInstaceGenerator, );
printILInstaceGenerator.Emit(OpCodes.Call, writeStringLineMethod);
printILInstaceGenerator.Emit(OpCodes.Ret);
} public static void LoadArg(ILGenerator ilGenerator, int argIndex)
{
switch (argIndex)
{
case :
ilGenerator.Emit(OpCodes.Ldarg_0);
return;
case :
ilGenerator.Emit(OpCodes.Ldarg_1);
return;
case :
ilGenerator.Emit(OpCodes.Ldarg_2);
return;
case :
ilGenerator.Emit(OpCodes.Ldarg_3);
return;
}
if (argIndex > && argIndex <= )
{
ilGenerator.Emit(OpCodes.Ldarg_S, argIndex);
return;
}
else
{
ilGenerator.Emit(OpCodes.Ldarg, argIndex);
return;
}
} public static void StormArg(ILGenerator ilGenerator, int argIndex)
{
if (argIndex > && argIndex <= )
{
ilGenerator.Emit(OpCodes.Starg_S, argIndex);
return;
}
else
{
ilGenerator.Emit(OpCodes.Starg, argIndex);
return;
}
} static void Emit_PrintStatic()
{
printStaticMethod = typeBuilder.DefineMethod("PrintStaticArg", MethodAttributes.Public
| MethodAttributes.Static, typeof(void), new Type[] { typeof(int), typeof(int), typeof(int), typeof(int), typeof(string) });
ILGenerator printILGenerator = printStaticMethod.GetILGenerator();
ParameterBuilder ab1 = printStaticMethod.DefineParameter(, ParameterAttributes.None, "i1");
ParameterBuilder ab2 = printStaticMethod.DefineParameter(, ParameterAttributes.None, "i2");
ParameterBuilder ab3 = printStaticMethod.DefineParameter(, ParameterAttributes.None, "i3");
ParameterBuilder ab4 = printStaticMethod.DefineParameter(, ParameterAttributes.None, "i4");
ParameterBuilder ab5 = printStaticMethod.DefineParameter(, ParameterAttributes.None, "s5"); MethodInfo writeIntLineMethod = typeof(Console).GetMethod("WriteLine", new Type[] { typeof(int) });
MethodInfo writeStringLineMethod = typeof(Console).GetMethod("WriteLine", new Type[] { typeof(string) });
printILGenerator.Emit(OpCodes.Ldarg_0);
printILGenerator.Emit(OpCodes.Call, writeIntLineMethod);
printILGenerator.Emit(OpCodes.Ldarg_1);
printILGenerator.Emit(OpCodes.Call, writeIntLineMethod);
printILGenerator.Emit(OpCodes.Ldarg_2);
printILGenerator.Emit(OpCodes.Call, writeIntLineMethod);
printILGenerator.Emit(OpCodes.Ldarg_3);
printILGenerator.Emit(OpCodes.Call, writeIntLineMethod);
printILGenerator.Emit(OpCodes.Ldarg_S,);
printILGenerator.Emit(OpCodes.Call, writeStringLineMethod);
printILGenerator.Emit(OpCodes.Ldstr, "world");
printILGenerator.Emit(OpCodes.Starg_S, );
printILGenerator.Emit(OpCodes.Ldarg_S, );
printILGenerator.Emit(OpCodes.Call, writeStringLineMethod);
printILGenerator.Emit(OpCodes.Ret);
} public static void Generate()
{
InitAssembly();
typeBuilder = moduleBuilder.DefineType( namespaceName+"."+ typeName, TypeAttributes.Public);
constructorBuilder = typeBuilder.DefineDefaultConstructor( MethodAttributes.Public);
Emit_PrintStatic();
Emit_PrintInstace();
EmitMain(); /* 设置assembly入口方法 */
assemblyBuilder.SetEntryPoint(mainMethod, PEFileKinds.ConsoleApplication);
SaveAssembly();
Console.WriteLine("生成成功");
} static void EmitMain()
{
mainMethod = typeBuilder.DefineMethod("Main", MethodAttributes.Public
| MethodAttributes.Static, typeof(void), new Type[] { });
ILGenerator mainILGenerator = mainMethod.GetILGenerator(); mainILGenerator.Emit(OpCodes.Ldc_I4,(int));
mainILGenerator.Emit(OpCodes.Ldc_I4, (int));
mainILGenerator.Emit(OpCodes.Ldc_I4, (int));
mainILGenerator.Emit(OpCodes.Ldc_I4, (int));
mainILGenerator.Emit(OpCodes.Ldstr,"hello static");
mainILGenerator.Emit(OpCodes.Call, printStaticMethod); LocalBuilder localBuilder = mainILGenerator.DeclareLocal(typeof(string));
mainILGenerator.Emit(OpCodes.Newobj, constructorBuilder);
mainILGenerator.Emit(OpCodes.Stloc_0);
mainILGenerator.Emit(OpCodes.Ldloc_0);
mainILGenerator.Emit(OpCodes.Ldc_I4, (int));
mainILGenerator.Emit(OpCodes.Ldc_I4, (int));
mainILGenerator.Emit(OpCodes.Ldc_I4, (int));
mainILGenerator.Emit(OpCodes.Ldc_I4, (int));
mainILGenerator.Emit(OpCodes.Ldstr, "hello instance");
mainILGenerator.Emit(OpCodes.Call, printInstaceMethod); MethodInfo readKeyMethod = typeof(Console).GetMethod("ReadKey", new Type[] { });
mainILGenerator.Emit(OpCodes.Call, readKeyMethod);
mainILGenerator.Emit(OpCodes.Pop);
mainILGenerator.Emit(OpCodes.Ret); } static void InitAssembly()
{
AssemblyName assemblyName = new AssemblyName(namespaceName);
assemblyBuilder = AppDomain.CurrentDomain.DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.RunAndSave);
moduleBuilder = assemblyBuilder.DefineDynamicModule(assemblyName.Name, binaryName);
} static void SaveAssembly()
{
Type t = typeBuilder.CreateType(); //完成Type，这是必须的
assemblyBuilder.Save(binaryName);
}
}
}
