mbed/platform/CThunk.h

/** \addtogroup platform */
/** @{*/
/* 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) 2014-2015 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.
 */

/* 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)
 */

#ifndef __CTHUNK_H__
#define __CTHUNK_H__

#define CTHUNK_ADDRESS 1
#define CTHUNK_VARIABLES volatile uint32_t code[2]

#if (defined(__CORTEX_M3) || defined(__CORTEX_M4) || defined(__CORTEX_M7) || defined(__CORTEX_A9))
/**
* CTHUNK disassembly for Cortex-M3/M4/M7/A9 (thumb2):
* * adr  r0, #4
* * ldm  r0, {r0, r1, r2, pc}
*
* This instruction loads the arguments for the static thunking function to r0-r2, and
* branches to that function by loading its address into PC.
*
* This is safe for both regular calling and interrupt calling, since it only touches scratch registers
* which should be saved by the caller, and are automatically saved as part of the IRQ context switch.
*/
#define CTHUNK_ASSIGMENT do {                              \
                             m_thunk.code[0] = 0xE890A001; \
                             m_thunk.code[1] = 0x00008007; \
                         } while (0)

#elif (defined(__CORTEX_M0PLUS) || defined(__CORTEX_M0))
/*
* CTHUNK disassembly for Cortex M0/M0+ (thumb):
* * adr  r0, #4
* * ldm  r0, {r0, r1, r2, r3}
* * bx   r3
*/
#define CTHUNK_ASSIGMENT do {                              \
                             m_thunk.code[0] = 0xC80FA001; \
                             m_thunk.code[1] = 0x00004718; \
                         } while (0)

#else
#error "Target is not currently suported."
#endif

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

/**
 * Class for created a pointer with data bound to it
 *
 * @Note Synchronization level: Not protected
 */
template<class T>
class CThunk
{
    public:
        typedef void (T::*CCallbackSimple)(void);
        typedef void (T::*CCallback)(void* context);

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

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

        ~CThunk() {

        }

        inline CThunk(T *instance, CCallbackSimple callback)
        {
            init(instance, (CCallback)callback, 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 void callback(CCallback callback)
        {
            m_callback = callback;
        }

        inline void callback(CCallbackSimple callback)
        {
            m_callback = (CCallback)callback;
        }

        inline void context(void* context)
        {
            m_thunk.context = (uint32_t)context;
        }

        inline void context(uint32_t context)
        {
            m_thunk.context = context;
        }

        inline uint32_t entry(void)
        {
            return (((uint32_t)&m_thunk)|CTHUNK_ADDRESS);
        }

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

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

        /* simple test function */
        inline void call(void)
        {
            (((CThunkEntry)(entry()))());
        }

    private:
        T* m_instance;
        volatile CCallback m_callback;

// TODO: this needs proper fix, to refactor toolchain header file and all its use
// PACKED there is not defined properly for IAR
#if defined (__ICCARM__)
        typedef __packed struct
        {
            CTHUNK_VARIABLES;
            volatile uint32_t instance;
            volatile uint32_t context;
            volatile uint32_t callback;
            volatile uint32_t trampoline;
        }  CThunkTrampoline;
#else
        typedef struct
        {
            CTHUNK_VARIABLES;
            volatile uint32_t instance;
            volatile uint32_t context;
            volatile uint32_t callback;
            volatile uint32_t trampoline;
        } __attribute__((__packed__)) CThunkTrampoline;
#endif

        static void trampoline(T* instance, void* context, CCallback* callback)
        {
            if(instance && *callback) {
                (static_cast<T*>(instance)->**callback)(context);
            }
        }

        volatile CThunkTrampoline m_thunk;

        inline void init(T *instance, CCallback callback, void* context)
        {
            /* remember callback - need to add this level of redirection
               as pointer size for member functions differs between platforms */
            m_callback = callback;

            /* populate thunking trampoline */
            CTHUNK_ASSIGMENT;
            m_thunk.context = (uint32_t)context;
            m_thunk.instance = (uint32_t)instance;
            m_thunk.callback = (uint32_t)&m_callback;
            m_thunk.trampoline = (uint32_t)&trampoline;

#if defined(__CORTEX_A9)
            /* Data cache clean */
            /* Cache control */
            {
                uint32_t start_addr = (uint32_t)&m_thunk & 0xFFFFFFE0;
                uint32_t end_addr   = (uint32_t)&m_thunk + sizeof(m_thunk);
                uint32_t addr;

                /* Data cache clean and invalid */
                for (addr = start_addr; addr < end_addr; addr += 0x20) {
                    __v7_clean_inv_dcache_mva((void *)addr);
                }
                /* Instruction cache invalid */
                __v7_inv_icache_all();
                __ca9u_inv_tlb_all();
                __v7_inv_btac();
            }
#endif
#if defined(__CORTEX_M7)
            /* Data cache clean and invalid */
            SCB_CleanInvalidateDCache();

            /* Instruction cache invalid */
            SCB_InvalidateICache();
#endif
            __ISB();
            __DSB();
        }
};

#endif/*__CTHUNK_H__*/

/** @}*/