jtie_tconv_utils_impl.hpp

/*
 Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.

 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation; version 2 of the License.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA
*/
/*
 * jtie_tconv_utils_impl.hpp
 */

#ifndef jtie_tconv_utils_impl_hpp
#define jtie_tconv_utils_impl_hpp

#include <jni.h>

//#include "helpers.hpp"

// ---------------------------------------------------------------------------
// Java <-> C type conversion utilities
// ---------------------------------------------------------------------------

// provides some (meta) predicates on types
template< typename C >
struct TypeInfo {
    // indicates whether a type is const
    static bool isMutable() {
        return true;
    }
};

// partial specialization for const types
template< typename C >
struct TypeInfo< const C > {
    static bool isMutable() {
        return false;
    }
};

// registers an exception with JNI for this thread
inline void
registerException(JNIEnv * env, const char * jvmClassName, const char * msg) 
{
    jclass ec = env->FindClass(jvmClassName);
    if (ec == NULL) {
        // exception pending
    } else {
        env->ThrowNew(ec, msg);
        env->DeleteLocalRef(ec);
        // exception pending
    }
}

// returns a value in big endian format
template<typename C>
C
big_endian(C c)
{
    // test if big or little endian
    C r = 1;
    if(*(char *)&r == 0) {
        // big endian, ok
        return c;
    }

    // little-endian, reverse byte order (better: use optimized swap macros)
    const size_t n = sizeof(C);
    char * s = (char *)&c;
    char * t = (char *)&r;
    for (int i = n-1, j = 0; i >= 0; i--, j++)
        t[j] = s[i];
    return r;
}

// ---------------------------------------------------------------------------

#endif // jtie_tconv_utils_impl_hpp