Пример #1
0
        public static SObject findCode(string module, string ns, int id, int number)
        {
            // First look in programAssembly

            CodeVector cv = findCodeInAssembly(Reg.programAssembly, ns, number);

            if (cv != null)
            {
                return(cv);
            }

            // Then look in external Assembly via module in name

            Assembly moduleAssembly;

            try {
                moduleAssembly = Assembly.LoadFrom(module + ".exe");
            }
            catch {
                try {
                    moduleAssembly = Assembly.LoadFrom(module + ".dll");
                }
                catch {
                    Exn.error("code not found (no EXE or DLL file): " + module);
                    return(Factory.Impossible);
                }
            }
            cv = findCodeInAssembly(moduleAssembly, ns, number);
            if (cv != null)
            {
                return(cv);
            }
            Exn.error("code not found: " + module + " " + ns + " " + number);
            return(Factory.False);
        }
Пример #2
0
 public static void ffi_syscall()
 {
     try
     {
         SObject scode = Reg.Register2;
         ffi_syscall_main(((SFixnum)scode).value);
     }
     catch (Exception e)
     {
         Exn.error("exception in ffi: " + e.ToString());
     }
 }
Пример #3
0
 private static object unwrapF(SObject s)
 {
     if (s is SFixnum)
     {
         return(((SFixnum)s).value);
     }
     else if (s is ForeignBox)
     {
         return(((ForeignBox)s).value);
     }
     else
     {
         Exn.error("cannot unwrap foreign argument");
         return(Factory.Impossible);
     }
 }
Пример #4
0
        private static SObject foreign2datum(int conversion, SObject obj)
        {
            // foreign->datum : conversion F -> value
            object value;

            if (obj is ForeignBox)
            {
                value = ((ForeignBox)obj).value;
            }
            else if (obj is SFixnum)
            {
                value = ((SFixnum)obj).value;
            }
            else
            {
                Exn.error
                    ("foreign->datum: argument is not foreign-box or fixnum");
                return(Factory.Impossible);
            }

            switch (conversion)
            {
            case 0:
            {         // object
                return(obj);
            }

            case 1:
            {         // schemeobject
                if (value is SObject)
                {
                    return((SObject)value);
                }
                else
                {
                    Exn.error("foreign->datum (schemeobject): not a scheme value");
                    return(Factory.Impossible);
                }
            }

            case 2:
            {         // string
                if (value is string)
                {
                    return(Factory.makeUString((string)value));
                }
                else
                {
                    Exn.error("foreign->datum (string): not a string");
                    return(Factory.Impossible);
                }
            }

            case 3:
            {         // symbol
                Exn.error
                    ("foreign->datum (symbol): not handled by runtime");
                return(Factory.Impossible);
            }

            case 4:
            {         // bytes
                if (value is byte[])
                {
                    return(Factory.makeByteVector
                               ((byte[])((byte[])value).Clone()));
                }
                else
                {
                    Exn.error("foreign->datum (bytes): not byte[]");
                    return(Factory.Impossible);
                }
            }

            case 5:
            {         // int
                if (value is Enum)
                {
                    Type enum_type = value.GetType();
                    Type underlying_type
                        = Enum.GetUnderlyingType(enum_type);
                    if (underlying_type == typeof(Byte))
                    {
                        return(Factory.makeFixnum((byte)value));
                    }
                    if (underlying_type == typeof(SByte))
                    {
                        return(Factory.makeFixnum((sbyte)value));
                    }
                    if (underlying_type == typeof(char))
                    {
                        return(Factory.makeFixnum((char)value));
                    }
                    if (underlying_type == typeof(short))
                    {
                        return(Factory.makeFixnum((short)value));
                    }
                    if (underlying_type == typeof(int))
                    {
                        return(Factory.makeNumber((int)value));
                    }
                    if (underlying_type == typeof(long))
                    {
                        return(Factory.makeNumber((long)value));
                    }
                    if (underlying_type == typeof(ushort))
                    {
                        return(Factory.makeFixnum((ushort)value));
                    }
                    if (underlying_type == typeof(uint))
                    {
                        return(Factory.makeNumber((uint)value));
                    }
                    if (underlying_type == typeof(ulong))
                    {
                        return(Factory.makeNumber((ulong)value));
                    }
                    Exn.error("foreign->datum (enum): not an integer");
                    return(Factory.Impossible);
                }
                if (value is Byte)
                {
                    return(Factory.makeFixnum((byte)value));
                }
                if (value is SByte)
                {
                    return(Factory.makeFixnum((sbyte)value));
                }
                if (value is char)
                {
                    return(Factory.makeFixnum((char)value));
                }
                if (value is short)
                {
                    return(Factory.makeFixnum((short)value));
                }
                if (value is int)
                {
                    return(Factory.makeNumber((int)value));
                }
                if (value is long)
                {
                    return(Factory.makeNumber((long)value));
                }
                if (value is ushort)
                {
                    return(Factory.makeFixnum((ushort)value));
                }
                if (value is uint)
                {
                    return(Factory.makeNumber((uint)value));
                }
                if (value is ulong)
                {
                    return(Factory.makeNumber((ulong)value));
                }

                Exn.error("foreign->datum (int): not an integer");
                return(Factory.Impossible);
            }

            case 6:
            {         // float
                if (value is float)
                {
                    return(Factory.makeFlonum((float)value));
                }
                else
                {
                    Exn.error("foreign->datum (float): not a float");
                    return(Factory.Impossible);
                }
            }

            case 7:
            {         // double
                if (value is double)
                {
                    return(Factory.makeFlonum((double)value));
                }
                else
                {
                    Exn.error("foreign->datum (double): not a double");
                    return(Factory.Impossible);
                }
            }

            case 8:
            {         // void
                return(Factory.Unspecified);
            }
            }
            Exn.error("foreign->datum: unknown conversion");
            return(Factory.Impossible);
        }
Пример #5
0
        private static SObject datum2foreign(int conversion, SObject obj)
        {
            // datum->foreign : conversion value -> F

            // Always returns a foreign box.  Contents of the box is controlled
            // by the conversion switch.
            switch (conversion)
            {
            // No conversion.  Scheme object is placed in the box.
            case 0:
            {
                return(Factory.makeForeignBox(obj));
            }

            // String.
            case 1:
            {
                return(Factory.makeForeignBox
                           (((SByteVL)obj).asString()));
            }

            // various integer forms
            case 2:
            {
                return(Factory.makeForeignBox
                           ((Byte)((SFixnum)obj).value));
            }

            case 3:
            {
                return(Factory.makeForeignBox
                           ((UInt16)((SFixnum)obj).value));
            }

            case 4:
            {
                return(Factory.makeForeignBox
                           ((UInt32)((SFixnum)obj).value));
            }

            case 5:
            {
                return(Factory.makeForeignBox
                           ((SByte)((SFixnum)obj).value));
            }

            case 6:
            {
                return(Factory.makeForeignBox
                           ((Int16)((SFixnum)obj).value));
            }

            case 7:
            {
                return(Factory.makeForeignBox
                           ((Int32)((SFixnum)obj).value));
            }

            case 8:     // message filter
            {
#if HAS_WINDOWS_FORMS
                return(Factory.makeForeignBox
                           (new FFI_message_filter((Procedure)obj)));
#else
                Exn.error("datum->foreign (message_filter) not supported in this version");
                return(Factory.Impossible);
#endif
            }

            case 10:     // single precision float
            {
                return(Factory.makeForeignBox
                           ((float)((SByteVL)obj).unsafeAsDouble(0)));
            }

            case 11:     //double precision float
            {
                return(Factory.makeForeignBox
                           ((double)((SByteVL)obj).unsafeAsDouble(0)));
            }

            case 12:     // character
            {
                return(Factory.makeForeignBox((Char)((SChar)obj).val));
            }

            case 13:     // bytevector-like
            {
                object copy = ((SByteVL)obj).elements.Clone();
                return(Factory.makeForeignBox((byte[])copy));
            }

#if NEVER
            case 0:     // object
            {
                if (obj is SFixnum || obj is ForeignBox)
                {
                    return(obj);
                }
                else
                {
                    Exn.error("datum->foreign (object) expected F");
                    return(Factory.Impossible);
                }
            }

            case 1:     // schemeobject
            {
                return(Factory.makeForeignBox(obj));
            }

            case 2:     // string
            {
                if (obj is SByteVL)
                {
                    string value = ((SByteVL)obj).asString();
                    return(Factory.makeForeignBox(value));
                }
                else
                {
                    Exn.error("datum->foreign (string) expected string");
                    return(Factory.Impossible);
                }
            }

            case 3:     // symbol
            {
                Exn.error
                    ("datum->foreign (symbol) not implemented in runtime");
                return(Factory.Impossible);
            }

            case 4:     // bytes
            {
                if (obj is SByteVL)
                {
                    return(Factory.makeForeignBox
                               (((SByteVL)obj).elements));
                }
                else
                {
                    Exn.error
                        ("datum->foreign (bytes) expected bytevector");
                    return(Factory.Impossible);
                }
            }

            case 5:     // int
            {
                if (obj is SFixnum)
                {
                    return(obj);
                }
                else if (obj.isBignum())
                {
                    SByteVL n = (SByteVL)obj;
                    if (Number.getBignumLength(n) == 1)
                    {
                        uint magn = (uint)(Number.bignumRef(n, 1) << 16)
                                    + (uint)Number.bignumRef(n, 0);
                        int val = magn;
                        if (!(Number.getBignumSign(n)))
                        {
                            magn = -magn;
                        }
                        return(Factory.makeForeignBox(val));
                    }
                }
                Exn.error("datum->foreign (int) expected small integer");
                return(Factory.Impossible);
            }

            case 6:     // float
            {
                if (obj.isFlonum())
                {
                    double value = ((SByteVL)obj).unsafeAsDouble(0);
                    return(Factory.makeForeignBox((float)value));
                }
                else
                {
                    Exn.error("datum->foreign (float) expected flonum");
                    return(Factory.Impossible);
                }
            }

            case 7:     // double
            {
                if (obj.isFlonum())
                {
                    double value = ((SByteVL)obj).unsafeAsDouble(0);
                    return(Factory.makeForeignBox(value));
                }
                else
                {
                    Exn.error("datum->foreign (float) expected flonum");
                    return(Factory.Impossible);
                }
            }

            case 8:     // void
            {
                Exn.error("datum->foreign (void) not allowed");
                return(Factory.Impossible);
            }

            case 9:     // message filter
            {
                if (obj is Procedure)
                {
                    return(Factory.makeForeignBox
                               (new FFI_message_filter((Procedure)obj)));
                }
                else
                {
                    Exn.error
                        ("datum->foreign (message filter) expected procedure");
                    return(Factory.Impossible);
                }
            }
#endif
            }
            Exn.error("datum->foreign: unknown conversion");
            return(Factory.Impossible);
        }
Пример #6
0
        private static void ffi_syscall_main(int code)
        {
            // SObject arg1 = Reg.Register3;
            // SObject arg2 = Reg.Register4;
            // SObject arg3 = Reg.Register5;
            // SObject arg4 = Reg.Register6;
            switch (code)
            {
            case 0:      // clr-version
                // Return a list of integers indicating the version
                // of the CLR runtime.
            {
                Version v = Environment.Version;
                // return a list of 2, 3, or 4 elements
                Reg.Result =
                    Factory.makePair
                        (Factory.makeNumber(v.Major),
                        Factory.makePair
                            (Factory.makeNumber(v.Minor),
                            (v.Build == -1)
                                ? (SObject)Factory.Null
                                : (SObject)
                            Factory.makePair
                                (Factory.makeNumber(v.Build),
                                (v.Revision == -1)
                                    ? (SObject)Factory.Null
                                    : (SObject)
                                Factory.makePair
                                    (Factory.makeNumber(v.Revision),
                                    Factory.Null))));
                return;
            }

            case 1:     // ffi version
                // Return a list of integers indicating the version of
                // this FFI.
            {
                // Should actually do real versioning here.
                Reg.Result =
                    Factory.makePair
                        (Factory.makeNumber(0),
                        Factory.makePair(Factory.makeNumber(0),
                                         Factory.Null));
                return;
            }

            case 2:     // foreign?
                // Return True iff argument is a ForeignBox wrapper.
            {
                // SObject arg1 = Reg.Register3;
                // SObject arg2 = Reg.Register4;
                // SObject arg3 = Reg.Register5;
                // SObject arg4 = Reg.Register6;
                Reg.Result
                    = (Reg.Register3 is ForeignBox)
                              ? Factory.True : Factory.False;
                return;
            }

            case 3:     // to-string
            {
                SObject arg1 = Reg.Register3;
                object  val  = ((ForeignBox)arg1).value;
                Reg.Result
                    = Factory.makeUString((val == null)
                                                  ? "null" : val.ToString());
                return;
            }

            case 4:     // object-type
            {
                SObject arg1 = Reg.Register3;
                Reg.Result
                    = Factory.makeForeignBox
                          (((ForeignBox)arg1).value.GetType());
                return;
            }

            case 5:     // isa?
            {
                SObject arg1 = Reg.Register3;
                SObject arg2 = Reg.Register4;
                object  obj  = ((ForeignBox)arg1).value;
                Type    type = (Type)((ForeignBox)arg2).value;
                Reg.Result
                    = type.IsInstanceOfType(obj)
                              ? Factory.True : Factory.False;
                return;
            }

            case 6:     // foreign-eq?
            {
                // this is a mess and should be rewritten!  ~jrm

                SObject arg1 = Reg.Register3;
                SObject arg2 = Reg.Register4;
                // SObject arg3 = Reg.Register5;
                // SObject arg4 = Reg.Register6;
                if (arg1 == arg2)
                {
                    Reg.Result = Factory.True;
                }
                else if (arg1 is ForeignBox)
                {
                    if (arg2 is ForeignBox)
                    {
                        // We can't use the Equals method on null
                        // objects, so we have to test for those
                        // first.

                        if (((ForeignBox)arg1).value == null)
                        {
                            Reg.Result
                                = (((ForeignBox)arg2).value == null)
                                          ? Factory.True
                                          : Factory.False;
                        }
                        else if (((ForeignBox)arg2).value == null)
                        {
                            Reg.Result = Factory.False;
                        }
                        else
                        {
                            Reg.Result
                                = ((((ForeignBox)arg1).value)
                                   .Equals(((ForeignBox)arg2).value))
                                          ? Factory.True
                                          : Factory.False;
                        }
                    }
                    else if (arg2 is SFixnum)
                    {
                        Reg.Result = Factory.False;
                    }
                    else if (arg2 is SImmediate)
                    {
                        Reg.Result = Factory.False;
                    }
                    else
                    {
                        Exn.error("cannot unwrap foreign argument");
                    }
                }
                else if (arg1 is SFixnum)
                {
                    if (arg2 is SFixnum)
                    {
                        Reg.Result
                            = ((((ForeignBox)arg1).value)
                               == (((ForeignBox)arg2).value))
                                      ? Factory.True
                                      : Factory.False;
                    }
                    else if (arg2 is ForeignBox)
                    {
                        Reg.Result = Factory.False;
                    }
                    else if (arg2 is SImmediate)
                    {
                        Reg.Result = Factory.False;
                    }
                    else
                    {
                        Exn.error("cannot unwrap foreign argument");
                    }
                }

                else if (arg1 is SImmediate)
                {
                    if (arg2 is SImmediate)
                    {
                        Reg.Result = Factory.False;
                    }
                    else if (arg2 is ForeignBox)
                    {
                        Reg.Result = Factory.False;
                    }
                    else if (arg2 is SFixnum)
                    {
                        Reg.Result = Factory.False;
                    }
                    else
                    {
                        Exn.error("cannot unwrap foreign argument");
                    }
                }
                else
                {
                    Exn.error("cannot unwrap foreign argument");
                }
                return;
            }

            case 7:     // get type
            {
                // SObject arg1 = Reg.Register3;
                // string name = ((SByteVL)arg1).asString();
                // case insensitive lookup
                Type ft = Type.GetType(((SByteVL)(Reg.Register3))
                                       .asString(), false, true);
                // Return #F if not found.
                Reg.Result = (ft == null)
                                     ? Factory.False
                                     : Factory.makeForeignBox(ft);
                return;
            }

            // return the reflected field-info object associated with
            // a named field, or #F if not found

            case 8:     // get field
            {
                SObject   arg1 = Reg.Register3;
                SObject   arg2 = Reg.Register4;
                FieldInfo fi   = ((Type)((ForeignBox)arg1).value)
                                 .GetField(((SByteVL)arg2).asString());
                Reg.Result = (fi == null)
                                     ? Factory.False
                                     : Factory.makeForeignBox(fi);
                return;
            }

            // return the reflected constructor
            // #F if not found

            case 9:     // get-constructor
            {
                SObject   arg1  = Reg.Register3;
                SObject   arg2  = Reg.Register4;
                SObject[] typev = ((SVL)arg2).elements;
                Type[]    types = new Type[typev.Length];
                for (int i = 0; i < types.Length; ++i)
                {
                    types[i] = (Type)((ForeignBox)typev[i]).value;
                }
                ConstructorInfo ci = ((Type)((ForeignBox)arg1).value)
                                     .GetConstructor(types);
                Reg.Result = (ci == null)
                                     ? Factory.False
                                     : Factory.makeForeignBox(ci);
                return;
            }

            case 10:     // get method
            {
                SObject   arg1  = Reg.Register3;
                SObject   arg2  = Reg.Register4;
                SObject   arg3  = Reg.Register5;
                SObject[] typev = ((SVL)arg3).elements;
                Type[]    types = new Type[typev.Length];
                for (int i = 0; i < types.Length; ++i)
                {
                    types[i] = (Type)((ForeignBox)typev[i]).value;
                }
                MethodInfo mi = ((Type)((ForeignBox)arg1).value)
                                .GetMethod(((SByteVL)arg2).asString(),
                                           types);
                Reg.Result = (mi == null)
                                     ? Factory.False
                                     : Factory.makeForeignBox(mi);
                return;
            }

            case 11:     // get property
            {
                SObject   arg1  = Reg.Register3;
                SObject   arg2  = Reg.Register4;
                SObject   arg3  = Reg.Register5;
                SObject[] typev = ((SVL)arg3).elements;
                Type[]    types = new Type[typev.Length];
                for (int i = 0; i < types.Length; ++i)
                {
                    types[i] = (Type)((ForeignBox)typev[i]).value;
                }
                PropertyInfo
                    pi = ((Type)((ForeignBox)arg1).value)
                         .GetProperty(((SByteVL)arg2).asString(),
                                      types);
                Reg.Result = (pi == null)
                                     ? Factory.False
                                     : Factory.makeForeignBox(pi);
                return;
            }

            case 12:     // field-ref
            {
                SObject   arg1 = Reg.Register3;
                SObject   arg2 = Reg.Register4;
                FieldInfo fi   = (FieldInfo)((ForeignBox)arg1).value;
                try
                {
                    Reg.Result
                        = Factory.makeForeignBox
                              (fi.GetValue(fi.IsStatic
                                                ? null
                                                : ((ForeignBox)arg2).value));
                    return;
                }
                catch (Exception e)
                {
                    Exn.error("ffi:field-get: " + e);
                    return;
                }
            }

            case 13:     // field-set!
            {
                SObject   arg1 = Reg.Register3;
                SObject   arg2 = Reg.Register4;
                SObject   arg3 = Reg.Register5;
                FieldInfo fi   = (FieldInfo)((ForeignBox)arg1).value;
                try
                {
                    fi.SetValue(fi.IsStatic
                                            ? null
                                            : ((ForeignBox)arg2).value,
                                ((ForeignBox)arg3).value);
                    Reg.Result = Factory.Unspecified;
                    return;
                }
                catch (Exception e)
                {
                    Exn.error("ffi:field-set: " + e);
                    return;
                }
            }

            case 14:     // invoke constructor
            {
                SObject         arg1 = Reg.Register3;
                SObject         arg2 = Reg.Register4;
                ConstructorInfo ci
                    = (ConstructorInfo)((ForeignBox)arg1).value;
                SObject[] sargv = ((SVL)arg2).elements;
                object[]  args  = new object[sargv.Length];
                for (int i = 0; i < args.Length; ++i)
                {
                    args[i] = ((ForeignBox)(sargv[i])).value;
                }
                try
                {
                    Reg.Result
                        = Factory.makeForeignBox(ci.Invoke(args));
                    return;
                }
                catch (Exception e)
                {
                    Exn.error("ffi:invoke-constructor: " + e);
                    return;
                }
            }

            case 15:     // invoke method
            {
                SObject    arg1  = Reg.Register3;
                SObject    arg2  = Reg.Register4;
                SObject    arg3  = Reg.Register5;
                MethodInfo mi    = (MethodInfo)((ForeignBox)arg1).value;
                SObject[]  sargv = ((SVL)arg3).elements;
                object[]   args  = new object[sargv.Length];
                for (int i = 0; i < args.Length; i++)
                {
                    args[i] = ((ForeignBox)(sargv[i])).value;
                }

                // I wonder if this version is better?
                //    int i = 0;
                //    foreach (SObject sarg in sargv)
                //      args [i++] = ((ForeignBox) sarg).value;

                object result;
                try
                {
                    result = mi.Invoke(mi.IsStatic
                                                   ? null
                                                   : ((ForeignBox)arg2).value,
                                       args);
                }
                catch (Exception e)
                {
                    Exn.error
                        ("ffi:invoke: error in foreign function: " + e);
                    return;
                }

                Reg.Result = Factory.makeForeignBox(result);
                return;
            }

            case 16:     // property-ref
            {
                SObject   arg1  = Reg.Register3;
                SObject   arg2  = Reg.Register4;
                SObject   arg3  = Reg.Register5;
                SObject[] sargv = ((SVL)arg3).elements;
                object[]  args  = new object[sargv.Length];
                for (int i = 0; i < args.Length; ++i)
                {
                    args[i] = ((ForeignBox)(sargv[i])).value;
                }
                object result;
                try
                {
                    result
                        = ((PropertyInfo)((ForeignBox)arg1).value)
                          .GetValue(((ForeignBox)arg2).value, args);
                }
                catch (Exception e)
                {
                    Exn.error
                        ("ffi:invoke: error in foreign function: " + e);
                    return;
                }
                Reg.Result = Factory.makeForeignBox(result);
                return;
            }

            case 17:     // property-set
            {
                SObject   arg1  = Reg.Register3;
                SObject   arg2  = Reg.Register4;
                SObject   arg3  = Reg.Register5;
                SObject   arg4  = Reg.Register6;
                SObject[] sargv = ((SVL)arg4).elements;
                object[]  args  = new object[sargv.Length];
                for (int i = 0; i < args.Length; ++i)
                {
                    args[i] = ((ForeignBox)(sargv[i])).value;
                }
                try
                {
                    ((PropertyInfo)
                     ((ForeignBox)arg1).value)
                    .SetValue(((ForeignBox)arg2).value,
                              ((ForeignBox)arg3).value,
                              args);
                }
                catch (Exception e)
                {
                    Exn.error
                        ("ffi:invoke: error in foreign function: " + e);
                    return;
                }
                Reg.Result = Factory.Unspecified;
                return;
            }

            case 18:     // array ref
            {
                SObject arg1 = Reg.Register3;
                SObject arg2 = Reg.Register4;
                Reg.Result
                    = Factory.makeForeignBox
                          (((Array)
                            ((ForeignBox)arg1).value)
                          .GetValue(((SFixnum)arg2).value));
                return;
            }

            case 19:     // datum2foreign
            {
                SObject arg1 = Reg.Register3;
                SObject arg2 = Reg.Register4;
                Reg.Result = datum2foreign(((SFixnum)arg1).value, arg2);
                return;
            }

            case 20:     // foreign2datum
            {
                SObject arg1 = Reg.Register3;
                SObject arg2 = Reg.Register4;
                Reg.Result = foreign2datum(((SFixnum)arg1).value, arg2);
                return;
            }

            case 21:     // get-property-value-boolean
            {
                SObject   arg1  = Reg.Register3;
                SObject   arg2  = Reg.Register4;
                SObject   arg3  = Reg.Register5;
                SObject[] sargv = ((SVL)arg3).elements;
                object[]  args  = new object[sargv.Length];
                for (int i = 0; i < args.Length; ++i)
                {
                    args[i] = ((ForeignBox)(sargv[i])).value;
                }
                object result;
                try
                {
                    result
                        = ((PropertyInfo)
                           ((ForeignBox)arg1).value)
                          .GetValue(((ForeignBox)arg2).value, args);
                }
                catch (Exception e)
                {
                    Exn.error
                        ("ffi:invoke: error in foreign function: " + e);
                    return;
                }
                Reg.Result
                    = Factory.makeBoolean((bool)result != false);
                return;
            }

            case 22:     // get-property-value-int
            {
                SObject   arg1  = Reg.Register3;
                SObject   arg2  = Reg.Register4;
                SObject   arg3  = Reg.Register5;
                SObject[] sargv = ((SVL)arg3).elements;
                object[]  args  = new object[sargv.Length];
                for (int i = 0; i < args.Length; ++i)
                {
                    args[i] = ((ForeignBox)(sargv[i])).value;
                }
                object result;
                try
                {
                    result
                        = ((PropertyInfo)
                           ((ForeignBox)arg1).value)
                          .GetValue(((ForeignBox)arg2).value, args);
                }
                catch (Exception e)
                {
                    Exn.error
                        ("ffi:invoke: error in foreign function: " + e);
                    return;
                }
                Reg.Result = Factory.makeNumber((int)result);
                return;
            }

#if HAS_WINDOWS_FORMS
            case 23: // get-property-value-native-window
            {
                SObject   arg1  = Reg.Register3;
                SObject   arg2  = Reg.Register4;
                SObject   arg3  = Reg.Register5;
                SObject[] sargv = ((SVL)arg3).elements;
                object[]  args  = new object [sargv.Length];
                for (int i = 0; i < args.Length; ++i)
                {
                    args[i] = ((ForeignBox)(sargv[i])).value;
                }
                object result;
                try {
                    result
                        = ((PropertyInfo)
                           ((ForeignBox)arg1).value)
                          .GetValue(((ForeignBox)arg2).value, args);
                }
                catch (Exception e) {
                    Exn.error("ffi:invoke: error in foreign function: " + e);
                    return;
                }
                Reg.Result
                    = Factory.makeForeignBox
                          (System.Windows.Forms.NativeWindow.FromHandle
                              ((IntPtr)result));
                return;
            }
#else
            case 23:
            {
                Exn.error("ffi:invoke property-value as native-window not supported in this version");
                return;
            }
#endif

            case 24:     // get-property-value-intptr
            {
                SObject   arg1  = Reg.Register3;
                SObject   arg2  = Reg.Register4;
                SObject   arg3  = Reg.Register5;
                SObject[] sargv = ((SVL)arg3).elements;
                object[]  args  = new object[sargv.Length];
                for (int i = 0; i < args.Length; ++i)
                {
                    args[i] = ((ForeignBox)(sargv[i])).value;
                }
                object result;
                try
                {
                    result
                        = ((PropertyInfo)
                           ((ForeignBox)arg1).value)
                          .GetValue(((ForeignBox)arg2).value, args);
                }
                catch (Exception e)
                {
                    Exn.error
                        ("ffi:invoke: error in foreign function: " + e);
                    return;
                }
                Reg.Result = Factory.makeNumber((int)((IntPtr)result));
                return;
            }

            case 25:                          // add-event-handler
            {
                SObject arg1 = Reg.Register3; // publisher
                SObject arg2 = Reg.Register4; // event-name
                SObject arg3 = Reg.Register5; // procedure (handler)

                try
                {
                    // cast arguments to appropriate types
                    object    publisher = ((ForeignBox)arg1).value;
                    string    eventName = ((SByteVL)arg2).asString();
                    Procedure proc
                        = (Procedure)(((ForeignBox)arg3).value);

                    // get information about the event
                    EventInfo ei
                        = publisher.GetType().GetEvent(eventName);

                    // add handler for the event
                    ei.AddEventHandler(publisher,
                                       proc.makeEventHandler(ei));
                }
                catch (Exception e)
                {
                    Exn.error("ffi:add-event-handler: error in foreign function: " + e);
                    return;
                }

                // return true if we successfully added handler
                Reg.Result = Factory.True;
                return;
            }

            case 26:     // load-assembly(name, version, culture, publickey)
            {
                SObject arg1      = Reg.Register3;
                SObject arg2      = Reg.Register4;
                SObject arg3      = Reg.Register5;
                SObject arg4      = Reg.Register6;
                string  name      = ((SByteVL)arg1).asString();
                string  version   = ((SByteVL)arg2).asString();
                string  culture   = ((SByteVL)arg3).asString();
                string  publickey = ((SByteVL)arg4).asString();
                Load.LoadAssembly(name, version, culture, publickey);
                Reg.Result = Factory.Unspecified;
                return;
            }
            }

            Exn.error("bad ffi syscall code");
            return;
        }