Diff: api/CThunk.h

Revision:

525:c320967f86b9

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/api/CThunk.h	Tue Apr 28 11:45:12 2015 +0100
@@ -0,0 +1,202 @@
+/* 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__*/