Joachim Andersen / keypad

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FPointer.h@17:643241424fd2, 2019-10-03 (annotated)

Committer:
jRix
Date:
Thu Oct 03 13:21:53 2019 +0000
Revision:
17:643241424fd2
11

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jRix 17:643241424fd2 1 /*
jRix 17:643241424fd2 2 Copyright (c) 2011 Andy Kirkham
jRix 17:643241424fd2 3
jRix 17:643241424fd2 4 Permission is hereby granted, free of charge, to any person obtaining a copy
jRix 17:643241424fd2 5 of this software and associated documentation files (the "Software"), to deal
jRix 17:643241424fd2 6 in the Software without restriction, including without limitation the rights
jRix 17:643241424fd2 7 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
jRix 17:643241424fd2 8 copies of the Software, and to permit persons to whom the Software is
jRix 17:643241424fd2 9 furnished to do so, subject to the following conditions:
jRix 17:643241424fd2 10
jRix 17:643241424fd2 11 The above copyright notice and this permission notice shall be included in
jRix 17:643241424fd2 12 all copies or substantial portions of the Software.
jRix 17:643241424fd2 13
jRix 17:643241424fd2 14 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
jRix 17:643241424fd2 15 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
jRix 17:643241424fd2 16 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
jRix 17:643241424fd2 17 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
jRix 17:643241424fd2 18 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
jRix 17:643241424fd2 19 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
jRix 17:643241424fd2 20 THE SOFTWARE.
jRix 17:643241424fd2 21 */
jRix 17:643241424fd2 22
jRix 17:643241424fd2 23 #ifndef AJK_FPOINTER_H
jRix 17:643241424fd2 24 #define AJK_FPOINTER_H
jRix 17:643241424fd2 25
jRix 17:643241424fd2 26 namespace AjK {
jRix 17:643241424fd2 27
jRix 17:643241424fd2 28 class FPointerDummy;
jRix 17:643241424fd2 29
jRix 17:643241424fd2 30 /** FPointer - Adds callbacks that take and return a 32bit uint32_t data type.
jRix 17:643241424fd2 31 *
jRix 17:643241424fd2 32 * The Mbed library supplies a callback using the FunctionPointer object as
jRix 17:643241424fd2 33 * defined in FunctionPointer.h However, this callback system does not allow
jRix 17:643241424fd2 34 * the caller to pass a value to the callback. Likewise, the callback itself
jRix 17:643241424fd2 35 * cannot return a value.
jRix 17:643241424fd2 36 *
jRix 17:643241424fd2 37 * FPointer operates in the same way but allows the callback function to be
jRix 17:643241424fd2 38 * passed one arg, a uint32_t value. Additionally, the callback can return
jRix 17:643241424fd2 39 * a single uint32_t value. The reason for using uint32_t is that the Mbed
jRix 17:643241424fd2 40 * and the microcontroller (LPC1768) have a natural data size of 32bits and
jRix 17:643241424fd2 41 * this means we can use the uint32_t as a pointer. See example1.h for more
jRix 17:643241424fd2 42 * information. This example passes an "int" by passing a pointer to that
jRix 17:643241424fd2 43 * int as a 32bit value. Using this technique you can pass any value you like.
jRix 17:643241424fd2 44 * All you have to do is pass a pointer to your value cast to (uint32_t). Your
jRix 17:643241424fd2 45 * callback can the deference it to get the original value.
jRix 17:643241424fd2 46 *
jRix 17:643241424fd2 47 * example2.h shows how to do the same thing but demostrates how to specify
jRix 17:643241424fd2 48 * the callback into a class object/method.
jRix 17:643241424fd2 49 *
jRix 17:643241424fd2 50 * Finally, example3.h shows how to pass multiple values. In this example we
jRix 17:643241424fd2 51 * define a data structure and in the callback we pass a pointer to that
jRix 17:643241424fd2 52 * data structure thus allowing the callback to again get the values.
jRix 17:643241424fd2 53 *
jRix 17:643241424fd2 54 * Note, when passing pointers to variables to the callback, if the callback
jRix 17:643241424fd2 55 * function/method changes that variable's value then it will also change the
jRix 17:643241424fd2 56 * value the caller sees. If C pointers are new to you, you are strongly
jRix 17:643241424fd2 57 * advised to read up on the subject. It's pointers that often get beginners
jRix 17:643241424fd2 58 * into trouble when mis-used.
jRix 17:643241424fd2 59 *
jRix 17:643241424fd2 60 * @see example1.h
jRix 17:643241424fd2 61 * @see example2.h
jRix 17:643241424fd2 62 * @see example3.h
jRix 17:643241424fd2 63 * @see http://mbed.org/handbook/C-Data-Types
jRix 17:643241424fd2 64 * @see http://mbed.org/projects/libraries/svn/mbed/trunk/FunctionPointer.h
jRix 17:643241424fd2 65 */
jRix 17:643241424fd2 66 class FPointer {
jRix 17:643241424fd2 67
jRix 17:643241424fd2 68 protected:
jRix 17:643241424fd2 69
jRix 17:643241424fd2 70 //! C callback function pointer.
jRix 17:643241424fd2 71 uint32_t (*c_callback)(uint32_t);
jRix 17:643241424fd2 72
jRix 17:643241424fd2 73 //! C++ callback object/method pointer (the object part).
jRix 17:643241424fd2 74 FPointerDummy *obj_callback;
jRix 17:643241424fd2 75
jRix 17:643241424fd2 76 //! C++ callback object/method pointer (the method part).
jRix 17:643241424fd2 77 uint32_t (FPointerDummy::*method_callback)(uint32_t);
jRix 17:643241424fd2 78
jRix 17:643241424fd2 79 public:
jRix 17:643241424fd2 80
jRix 17:643241424fd2 81 /** Constructor
jRix 17:643241424fd2 82 */
jRix 17:643241424fd2 83 FPointer() {
jRix 17:643241424fd2 84 c_callback = NULL;
jRix 17:643241424fd2 85 obj_callback = NULL;
jRix 17:643241424fd2 86 method_callback = NULL;
jRix 17:643241424fd2 87 }
jRix 17:643241424fd2 88
jRix 17:643241424fd2 89 /** attach - Overloaded attachment function.
jRix 17:643241424fd2 90 *
jRix 17:643241424fd2 91 * Attach a C type function pointer as the callback.
jRix 17:643241424fd2 92 *
jRix 17:643241424fd2 93 * Note, the callback function prototype must be:-
jRix 17:643241424fd2 94 * @code
jRix 17:643241424fd2 95 * uint32_t myCallbackFunction(uint32_t);
jRix 17:643241424fd2 96 * @endcode
jRix 17:643241424fd2 97 * @param A C function pointer to call.
jRix 17:643241424fd2 98 */
jRix 17:643241424fd2 99 void attach(uint32_t (*function)(uint32_t) = 0) { c_callback = function; }
jRix 17:643241424fd2 100
jRix 17:643241424fd2 101 /** attach - Overloaded attachment function.
jRix 17:643241424fd2 102 *
jRix 17:643241424fd2 103 * Attach a C++ type object/method pointer as the callback.
jRix 17:643241424fd2 104 *
jRix 17:643241424fd2 105 * Note, the callback method prototype must be:-
jRix 17:643241424fd2 106 * @code
jRix 17:643241424fd2 107 * public:
jRix 17:643241424fd2 108 * uint32_t myCallbackFunction(uint32_t);
jRix 17:643241424fd2 109 * @endcode
jRix 17:643241424fd2 110 * @param A C++ object pointer.
jRix 17:643241424fd2 111 * @param A C++ method within the object to call.
jRix 17:643241424fd2 112 */
jRix 17:643241424fd2 113 template<class T>
jRix 17:643241424fd2 114 void attach(T* item, uint32_t (T::*method)(uint32_t)) {
jRix 17:643241424fd2 115 obj_callback = (FPointerDummy *)item;
jRix 17:643241424fd2 116 method_callback = (uint32_t (FPointerDummy::*)(uint32_t))method;
jRix 17:643241424fd2 117 }
jRix 17:643241424fd2 118
jRix 17:643241424fd2 119 /** call - Overloaded callback initiator.
jRix 17:643241424fd2 120 *
jRix 17:643241424fd2 121 * call the callback function.
jRix 17:643241424fd2 122 *
jRix 17:643241424fd2 123 * @param uint32_t The value to pass to the callback.
jRix 17:643241424fd2 124 * @return uint32_t The value the callback returns.
jRix 17:643241424fd2 125 */
jRix 17:643241424fd2 126 uint32_t call(uint32_t arg) {
jRix 17:643241424fd2 127 if (c_callback != NULL) {
jRix 17:643241424fd2 128 return (*c_callback)(arg);
jRix 17:643241424fd2 129 }
jRix 17:643241424fd2 130 else {
jRix 17:643241424fd2 131 if (obj_callback != NULL && method_callback != NULL) {
jRix 17:643241424fd2 132 return (obj_callback->*method_callback)(arg);
jRix 17:643241424fd2 133 }
jRix 17:643241424fd2 134 }
jRix 17:643241424fd2 135 return (uint32_t)NULL;
jRix 17:643241424fd2 136 }
jRix 17:643241424fd2 137
jRix 17:643241424fd2 138 /** call - Overloaded callback initiator.
jRix 17:643241424fd2 139 *
jRix 17:643241424fd2 140 * Call the callback function without passing an argument.
jRix 17:643241424fd2 141 * The callback itself is passed NULL. Note, the callback
jRix 17:643241424fd2 142 * prototype should still be <b>uint32_t callback(uint32_t)</b>.
jRix 17:643241424fd2 143 *
jRix 17:643241424fd2 144 * @return uint32_t The value the callback returns.
jRix 17:643241424fd2 145 */
jRix 17:643241424fd2 146 uint32_t call(void) {
jRix 17:643241424fd2 147 if (c_callback != NULL) {
jRix 17:643241424fd2 148 return (*c_callback)((uint32_t)NULL);
jRix 17:643241424fd2 149 }
jRix 17:643241424fd2 150 else {
jRix 17:643241424fd2 151 if (obj_callback != NULL && method_callback != NULL) {
jRix 17:643241424fd2 152 return (obj_callback->*method_callback)((uint32_t)NULL);
jRix 17:643241424fd2 153 }
jRix 17:643241424fd2 154 }
jRix 17:643241424fd2 155 return (uint32_t)NULL;
jRix 17:643241424fd2 156 }
jRix 17:643241424fd2 157 };
jRix 17:643241424fd2 158
jRix 17:643241424fd2 159 }; // namespace AjK ends
jRix 17:643241424fd2 160
jRix 17:643241424fd2 161 using namespace AjK;
jRix 17:643241424fd2 162
jRix 17:643241424fd2 163 #endif