File content as of revision 0:7de85300ea3a:

/* General C++ Object Thunking class
 *
 * - allows direct callbacks to non-static C++ class functions
 * - keeps track for the corresponding class instance
 * - supports an optional context parameter for the called function
 * - ideally suited for class object receiving interrupts (NVIC_SetVector)
 *
 * Copyright (c) 2014 ARM Limited
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 
#ifndef __CTHUNK_H__
#define __CTHUNK_H__

/* IRQ/Exception compatible thunk entry function */
typedef void (*CThunkEntry)(void);

/* template for thunk trampoline */
#ifdef __thumb__
#define CTHUNK_OPCODES_SIZE 8
#else
#error "TODO: add support for non-thumb trampoline, too"
#endif

extern const uint8_t g_cthunk_opcodes[CTHUNK_OPCODES_SIZE];

template<class T>
class CThunk
{
    public:
        typedef void (T::*CCallbackSimple)(void);
        typedef void (T::*CCallback)(void* context);

        inline CThunk(void)
        {
            /* copy ARM thumb compatible pcode preamble */
            memcpy(
                &m_thunk.code,
                &g_cthunk_opcodes,
                CTHUNK_OPCODES_SIZE
            );
            /* set remainder to zero */
            memset(
                &m_thunk.code + CTHUNK_OPCODES_SIZE,
                0, sizeof(m_thunk.code) - CTHUNK_OPCODES_SIZE
            );
        }

        inline CThunk(T &instance)
        {
            init(instance, NULL, NULL);
        }

        inline CThunk(T &instance, CCallback callback)
        {
            init(instance, callback, NULL);
        }

        inline CThunk(T &instance, CCallbackSimple callback)
        {
            init(instance, (CCallback)callback, NULL);
        }

        inline CThunk(T &instance, CCallback callback, void* context)
        {
            init(instance, callback, context);
        }

        inline CThunk& operator=(T &instance)
        {
            m_thunk.instance = &instance;
            return *this;
        }

        inline CThunk& operator=(CCallback callback)
        {
            m_thunk.callback = callback;
            return *this;
        }

        inline CThunk& operator=(CCallbackSimple callback)
        {
            m_thunk.callback = (CCallback)callback;
            return *this;
        }

        inline CThunk& operator=(void* context)
        {
            m_thunk.context = context;
            return *this;
        }

        inline CThunk& operator=(uint32_t context)
        {
            m_thunk.context = (void*)context;
            return *this;
        }

        /* get thunk entry point for connecting rhunk to an IRQ table */
        inline operator CThunkEntry(void)
        {
            return (CThunkEntry)&m_thunk.code;
        }

        /* get thunk entry point for connecting rhunk to an IRQ table */
        inline operator uint32_t(void)
        {
            return (uint32_t)&m_thunk.code;
        }

        /* simple test function */
        inline void call(void)
        {
            ((CThunkEntry)&m_thunk.code)();
        }

    private:
        typedef struct
        {
            uint8_t code[CTHUNK_OPCODES_SIZE];
            T* instance;
            void* context;
            CCallback callback;
        } __attribute__((packed)) CThunkTrampoline;

        CThunkTrampoline m_thunk;

        inline void init(T &instance, CCallback callback, void* context)
        {
            memcpy(&m_thunk.code, &g_cthunk_opcodes, CTHUNK_OPCODES_SIZE);
            m_thunk.instance = &instance;
            m_thunk.context = context;
            m_thunk.callback = callback;
        }
};

#endif/*__CTHUNK_H__*/