From 39ac72f2d12a9c62b2e876de4eee6c34a864ff74 Mon Sep 17 00:00:00 2001 From: Dean Camera Date: Sun, 26 Dec 2010 13:01:37 +0000 Subject: Make a new general RingBuffer.h misc library driver, instead of the per-application LightweightRingBuff.h ring buffers. Change over projects to use the new driver. Add ORDERED_EP_CONFIG to the device Projects (only) that use only a single class driver, or where the endpoint ordering is fixed, to save on compiled binary size. Added new GCC_FORCE_POINTER_ACCESS() macro to correct GCC's mishandling of struct pointers. --- LUFA/Drivers/Misc/RingBuffer.h | 254 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 254 insertions(+) create mode 100644 LUFA/Drivers/Misc/RingBuffer.h (limited to 'LUFA/Drivers/Misc') diff --git a/LUFA/Drivers/Misc/RingBuffer.h b/LUFA/Drivers/Misc/RingBuffer.h new file mode 100644 index 000000000..30493e33a --- /dev/null +++ b/LUFA/Drivers/Misc/RingBuffer.h @@ -0,0 +1,254 @@ +/* + 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. + * + * Example Usage: + * \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 + * printf("Buffer Length: %d, Buffer Data:\r\n", BufferCount); + * + * // 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 + +/** @} */ + -- cgit v1.2.3