// NativeCaller - generate code to call native functions at runtime
//
// (c) 2004-2007 
// Paul D. Senzee
// Senzee 5
// http://senzee.blogspot.com

#ifndef _NATIVECALLER_H
#define _NATIVECALLER_H

#include <stdio.h>
#include <stddef.h>
#include <string.h>
#include <conio.h>

class Object;

class NativeCaller
{
public:

    enum CallConvention { CALL_STDCALL, CALL_CDECL };

    // the function to be called is passed as a void pointer and the calling convention is specified
    // the out argument specifies the return type of the function one of 'v' - void, 'f' - float, 'u' - unsigned int, 's' - const char *
    // format is a string of characters, for example, 'u' and "ufuusf" for unsigned fn(unsigned, float, unsigned, unsigned, const char *, float)
    NativeCaller(void *function, CallConvention convention, char out, const char *format);

    inline unsigned arguments() const
    {
        return m_argcount;
    }

    inline Object *call(Object **array)
    {
        return m_typed_caller(&m_code[0], m_converters, m_function, array);
    }

private:

    enum { MAX_FUNCTION_SIZE = 512 };

    unsigned char   m_code[MAX_FUNCTION_SIZE];
    void           *m_function;
    unsigned        m_argcount;

    struct Converters
    {
        float       (*to_float)  (Object *);
        unsigned    (*to_uint)   (Object *);
        const char *(*to_string) (Object *);
        void       *(*to_pointer)(Object *);
    };
    // these must reflect the order of the above members
    enum Converter { CONVERT_FLOAT = 0, CONVERT_UINT = 1, CONVERT_STRING = 2, CONVERT_POINTER = 3 }; 

    typedef Object     *(*typed_caller)     (const unsigned char *, const Converters &, void *, Object **);

    typedef void        (*caller_void_t)    (const Converters &, void *, Object **);
    typedef float       (*caller_float_t)   (const Converters &, void *, Object **);
    typedef unsigned    (*caller_uint_t)    (const Converters &, void *, Object **);
    typedef const char *(*caller_string_t)  (const Converters &, void *, Object **);
    typedef void       *(*caller_pointer_t) (const Converters &, void *, Object **);

    Converters         m_converters;
    typed_caller       m_typed_caller;

    static void        m_unbox(unsigned char **c, unsigned i, Converter converter);
    static void        m_create_function(unsigned char *code, const char *format, CallConvention convention);

    static Object     *m_call_void   (const unsigned char *code, const Converters &converters, void *function, Object **array);
    static Object     *m_call_float  (const unsigned char *code, const Converters &converters, void *function, Object **array);
    static Object     *m_call_uint   (const unsigned char *code, const Converters &converters, void *function, Object **array);
    static Object     *m_call_string (const unsigned char *code, const Converters &converters, void *function, Object **array);
    static Object     *m_call_symbol (const unsigned char *code, const Converters &converters, void *function, Object **array);
    static Object     *m_call_pointer(const unsigned char *code, const Converters &converters, void *function, Object **array);
};

#endif  // _NATIVECALLER_H