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/* 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.
*/
#ifndef __CTHUNK_H__
#define __CTHUNK_H__
#define CTHUNK_ADDRESS 1
#if defined(__CORTEX_M3) || defined(__CORTEX_M4) || defined(__thumb2__)
#define CTHUNK_VARIABLES volatile uint32_t code[1]
/**
* CTHUNK disassembly for Cortex-M3/M4 (thumb2):
* * ldm.w pc,{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 m_thunk.code[0] = 0x8007E89F
#elif defined(__CORTEX_M0PLUS) || defined(__CORTEX_M0)
/*
* CTHUNK disassembly for Cortex M0 (thumb):
* * push {r0,r1,r2,r3,r4,lr} save touched registers and return address
* * movs r4,#4 set up address to load arguments from (immediately following this code block) (1)
* * add r4,pc set up address to load arguments from (immediately following this code block) (2)
* * ldm r4!,{r0,r1,r2,r3} load arguments for static thunk function
* * blx r3 call static thunk function
* * pop {r0,r1,r2,r3,r4,pc} restore scratch registers and return from function
*/
#define CTHUNK_VARIABLES volatile uint32_t code[3]
#define CTHUNK_ASSIGMENT do { \
m_thunk.code[0] = 0x2404B51F; \
m_thunk.code[1] = 0xCC0F447C; \
m_thunk.code[2] = 0xBD1F4798; \
} while (0)
#else
#error "Target is not currently suported."
#endif
/* IRQ/Exception compatible thunk entry function */
typedef void (*CThunkEntry)(void);
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;
__ISB();
__DSB();
}
};
#endif/*__CTHUNK_H__*/
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