RingBuffer.h 9.46 KB
 Dean Camera committed Dec 26, 2010 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 /* LUFA Library Copyright (C) Dean Camera, 2010. dean [at] fourwalledcubicle [dot] com www.lufa-lib.org */ /* Copyright 2010 Dean Camera (dean [at] fourwalledcubicle [dot] com) Permission to use, copy, modify, distribute, and sell this software and its documentation for any purpose is hereby granted without fee, provided that the above copyright notice appear in all copies and that both that the copyright notice and this permission notice and warranty disclaimer appear in supporting documentation, and that the name of the author not be used in advertising or publicity pertaining to distribution of the software without specific, written prior permission. The author disclaim all warranties with regard to this software, including all implied warranties of merchantability and fitness. In no event shall the author be liable for any special, indirect or consequential damages or any damages whatsoever resulting from loss of use, data or profits, whether in an action of contract, negligence or other tortious action, arising out of or in connection with the use or performance of this software. */ /** \file * \brief Lightweight ring buffer, for fast insertion/deletion. * * Lightweight ring buffer, for fast insertion/deletion. Multiple buffers can be created of * different sizes to suit different needs. * * Note that for each buffer, insertion and removal operations may occur at the same time (via * a multithreaded ISR based system) however the same kind of operation (two or more insertions * or deletions) must not overlap. If there is possibility of two or more of the same kind of * operating occuring at the same point in time, atomic (mutex) locking should be used. */ /** \ingroup Group_MiscDrivers * @defgroup Group_RingBuff Generic Byte Ring Buffer - LUFA/Drivers/Misc/RingBuffer.h * * \section Sec_Dependencies Module Source Dependencies * The following files must be built with any user project that uses this module: * - None * * \section Module Description * Lightweight ring buffer, for fast insertion/deletion. Multiple buffers can be created of * different sizes to suit different needs. * * Note that for each buffer, insertion and removal operations may occur at the same time (via * a multithreaded ISR based system) however the same kind of operation (two or more insertions * or deletions) must not overlap. If there is possibility of two or more of the same kind of * operating occuring at the same point in time, atomic (mutex) locking should be used. *  Dean Camera committed Dec 26, 2010 59  * Example Usage:  Dean Camera committed Dec 26, 2010 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78  * \code * // Create the buffer structure and its underlying storage array * RingBuff_t Buffer; * uint8_t BufferData[128]; * * // Initialise the buffer with the created storage array * RingBuffer_InitBuffer(&Buffer, BufferData, sizeof(BufferData)); * * // Insert some data into the buffer * RingBuffer_Insert(Buffer, 'H'); * RingBuffer_Insert(Buffer, 'E'); * RingBuffer_Insert(Buffer, 'L'); * RingBuffer_Insert(Buffer, 'L'); * RingBuffer_Insert(Buffer, 'O'); * * // Cache the number of stored bytes in the buffer * uint16_t BufferCount = RingBuffer_GetCount(&Buffer); * * // Printer stored data length  Dean Camera committed Dec 26, 2010 79  * printf("Buffer Length: %d, Buffer Data: \r\n", BufferCount);  Dean Camera committed Dec 26, 2010 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254  * * // Print contents of the buffer one character at a time * while (BufferCount--) * putc(RingBuffer_Remove(&Buffer)); * \endcode * * @{ */ #ifndef __RING_BUFF_H__ #define __RING_BUFF_H__ /* Includes: */ #include #include #include #include /* Type Defines: */ /** Type define for a new ring buffer object. Buffers should be initialized via a call to * \ref RingBuffer_InitBuffer() before use. */ typedef struct { uint8_t* In; /**< Current storage location in the circular buffer */ uint8_t* Out; /**< Current retrieval location in the circular buffer */ uint8_t* Start; /** Pointer to the start of the buffer's underlying storage array */ uint8_t* End; /** Pointer to the end of the buffer's underlying storage array */ uint8_t Size; /** Size of the buffer's underlying storage array */ uint16_t Count; /** Number of bytes currently stored in the buffer */ } RingBuff_t; /* Inline Functions: */ /** Initializes a ring buffer ready for use. Buffers must be initialized via this function * before any operations are called upon them. Already initialized buffers may be reset * by re-initializing them using this function. * * \param[out] Buffer Pointer to a ring buffer structure to initialize * \param[out] DataPtr Pointer to a global array that will hold the data stored into the ring buffer * \param[out] Size Maximum number of bytes that can be stored in the underlying data array */ static inline void RingBuffer_InitBuffer(RingBuff_t* Buffer, uint8_t* const DataPtr, const uint16_t Size) { ATOMIC_BLOCK(ATOMIC_RESTORESTATE) { GCC_FORCE_POINTER_ACCESS(Buffer); Buffer->In = DataPtr; Buffer->Out = DataPtr; Buffer->Start = &DataPtr[0]; Buffer->End = &DataPtr[Size]; Buffer->Size = Size; Buffer->Count = 0; } } /** Retrieves the minimum number of bytes stored in a particular buffer. This value is computed * by entering an atomic lock on the buffer while the IN and OUT locations are fetched, so that * the buffer cannot be modified while the computation takes place. This value should be cached * when reading out the contents of the buffer, so that as small a time as possible is spent * in an atomic lock. * * \note The value returned by this function is guaranteed to only be the minimum number of bytes * stored in the given buffer; this value may change as other threads write new data and so * the returned number should be used only to determine how many successive reads may safely * be performed on the buffer. * * \param[in] Buffer Pointer to a ring buffer structure whose count is to be computed */ static inline uint16_t RingBuffer_GetCount(RingBuff_t* const Buffer) { uint16_t Count; ATOMIC_BLOCK(ATOMIC_RESTORESTATE) { Count = Buffer->Count; } return Count; } /** Atomically determines if the specified ring buffer contains any free space. This should * be tested before storing data to the buffer, to ensure that no data is lost due to a * buffer overrun. * * \param[in,out] Buffer Pointer to a ring buffer structure to insert into * * \return Boolean true if the buffer contains no free space, false otherwise */ static inline bool RingBuffer_IsFull(RingBuff_t* const Buffer) { return (RingBuffer_GetCount(Buffer) == Buffer->Size); } /** Atomically determines if the specified ring buffer contains any data. This should * be tested before removing data from the buffer, to ensure that the buffer does not * underflow. * * If the data is to be removed in a loop, store the total number of bytes stored in the * buffer (via a call to the \ref RingBuffer_GetCount() function) in a temporary variable * to reduce the time spent in atomicity locks. * * \param[in,out] Buffer Pointer to a ring buffer structure to insert into * * \return Boolean true if the buffer contains no free space, false otherwise */ static inline bool RingBuffer_IsEmpty(RingBuff_t* const Buffer) { return (RingBuffer_GetCount(Buffer) == 0); } /** Inserts an element into the ring buffer. * * \note Only one execution thread (main program thread or an ISR) may insert into a single buffer * otherwise data corruption may occur. Insertion and removal may occur from different execution * threads. * * \param[in,out] Buffer Pointer to a ring buffer structure to insert into * \param[in] Data Data element to insert into the buffer */ static inline void RingBuffer_Insert(RingBuff_t* const Buffer, const uint8_t Data) { *Buffer->In = Data; if (++Buffer->In == Buffer->End) Buffer->In = Buffer->Start; ATOMIC_BLOCK(ATOMIC_RESTORESTATE) { Buffer->Count++; } } /** Removes an element from the ring buffer. * * \note Only one execution thread (main program thread or an ISR) may remove from a single buffer * otherwise data corruption may occur. Insertion and removal may occur from different execution * threads. * * \param[in,out] Buffer Pointer to a ring buffer structure to retrieve from * * \return Next data element stored in the buffer */ static inline uint8_t RingBuffer_Remove(RingBuff_t* const Buffer) { uint8_t Data = *Buffer->Out; if (++Buffer->Out == Buffer->End) Buffer->Out = Buffer->Start; ATOMIC_BLOCK(ATOMIC_RESTORESTATE) { Buffer->Count--; } return Data; } /** Returns the next element stored in the ring buffer, without removing it. * * \param[in,out] Buffer Pointer to a ring buffer structure to retrieve from * * \return Next data element stored in the buffer */ static inline uint8_t RingBuffer_Peek(RingBuff_t* const Buffer) { return *Buffer->Out; } #endif /** @} */