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Diffstat (limited to 'lib/lufa/LUFA/Drivers/Misc/RingBuffer.h')
| -rw-r--r-- | lib/lufa/LUFA/Drivers/Misc/RingBuffer.h | 308 |
1 files changed, 308 insertions, 0 deletions
diff --git a/lib/lufa/LUFA/Drivers/Misc/RingBuffer.h b/lib/lufa/LUFA/Drivers/Misc/RingBuffer.h new file mode 100644 index 0000000000..0e76a0779a --- /dev/null +++ b/lib/lufa/LUFA/Drivers/Misc/RingBuffer.h @@ -0,0 +1,308 @@ +/* + LUFA Library + Copyright (C) Dean Camera, 2017. + + dean [at] fourwalledcubicle [dot] com + www.lufa-lib.org +*/ + +/* + Copyright 2017 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 disclaims 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 (circular) buffer, for fast insertion/deletion of bytes. + * + * 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 multi-threaded 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 occurring 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 + * \brief Lightweight ring buffer, for fast insertion/deletion of bytes. + * + * \section Sec_RingBuff_Dependencies Module Source Dependencies + * The following files must be built with any user project that uses this module: + * - None + * + * \section Sec_RingBuff_ModDescription 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 multi-threaded 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 occurring at the same point in time, atomic (mutex) locking should be used. + * + * \section Sec_RingBuff_ExampleUsage Example Usage + * The following snippet is an example of how this module may be used within a typical + * application. + * + * \code + * // Create the buffer structure and its underlying storage array + * RingBuffer_t Buffer; + * uint8_t BufferData[128]; + * + * // Initialize 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_BUFFER_H__ +#define __RING_BUFFER_H__ + + /* Includes: */ + #include "../../Common/Common.h" + + /* Enable C linkage for C++ Compilers: */ + #if defined(__cplusplus) + extern "C" { + #endif + + /* Type Defines: */ + /** \brief Ring Buffer Management Structure. + * + * 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. */ + uint16_t Size; /**< Size of the buffer's underlying storage array. */ + uint16_t Count; /**< Number of bytes currently stored in the buffer. */ + } RingBuffer_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(RingBuffer_t* Buffer, + uint8_t* const DataPtr, + const uint16_t Size) ATTR_NON_NULL_PTR_ARG(1) ATTR_NON_NULL_PTR_ARG(2); + static inline void RingBuffer_InitBuffer(RingBuffer_t* Buffer, + uint8_t* const DataPtr, + const uint16_t Size) + { + GCC_FORCE_POINTER_ACCESS(Buffer); + + uint_reg_t CurrentGlobalInt = GetGlobalInterruptMask(); + GlobalInterruptDisable(); + + Buffer->In = DataPtr; + Buffer->Out = DataPtr; + Buffer->Start = &DataPtr[0]; + Buffer->End = &DataPtr[Size]; + Buffer->Size = Size; + Buffer->Count = 0; + + SetGlobalInterruptMask(CurrentGlobalInt); + } + + /** Retrieves the current number of bytes stored in a particular buffer. This value is computed + * by entering an atomic lock on the buffer, 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, thus + * 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. + * + * \return Number of bytes currently stored in the buffer. + */ + static inline uint16_t RingBuffer_GetCount(RingBuffer_t* const Buffer) ATTR_WARN_UNUSED_RESULT ATTR_NON_NULL_PTR_ARG(1); + static inline uint16_t RingBuffer_GetCount(RingBuffer_t* const Buffer) + { + uint16_t Count; + + uint_reg_t CurrentGlobalInt = GetGlobalInterruptMask(); + GlobalInterruptDisable(); + + Count = Buffer->Count; + + SetGlobalInterruptMask(CurrentGlobalInt); + return Count; + } + + /** Retrieves the free space in a particular buffer. This value is computed by entering an atomic lock + * on the buffer, so that the buffer cannot be modified while the computation takes place. + * + * \note The value returned by this function is guaranteed to only be the maximum number of bytes + * free in the given buffer; this value may change as other threads write new data, thus + * the returned number should be used only to determine how many successive writes may safely + * be performed on the buffer when there is a single writer thread. + * + * \param[in] Buffer Pointer to a ring buffer structure whose free count is to be computed. + * + * \return Number of free bytes in the buffer. + */ + static inline uint16_t RingBuffer_GetFreeCount(RingBuffer_t* const Buffer) ATTR_WARN_UNUSED_RESULT ATTR_NON_NULL_PTR_ARG(1); + static inline uint16_t RingBuffer_GetFreeCount(RingBuffer_t* const Buffer) + { + return (Buffer->Size - RingBuffer_GetCount(Buffer)); + } + + /** 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 \c true if the buffer contains no free space, \c false otherwise. + */ + static inline bool RingBuffer_IsEmpty(RingBuffer_t* const Buffer) ATTR_WARN_UNUSED_RESULT ATTR_NON_NULL_PTR_ARG(1); + static inline bool RingBuffer_IsEmpty(RingBuffer_t* const Buffer) + { + return (RingBuffer_GetCount(Buffer) == 0); + } + + /** 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 \c true if the buffer contains no free space, \c false otherwise. + */ + static inline bool RingBuffer_IsFull(RingBuffer_t* const Buffer) ATTR_WARN_UNUSED_RESULT ATTR_NON_NULL_PTR_ARG(1); + static inline bool RingBuffer_IsFull(RingBuffer_t* const Buffer) + { + return (RingBuffer_GetCount(Buffer) == Buffer->Size); + } + + /** Inserts an element into the ring buffer. + * + * \warning 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(RingBuffer_t* Buffer, + const uint8_t Data) ATTR_NON_NULL_PTR_ARG(1); + static inline void RingBuffer_Insert(RingBuffer_t* Buffer, + const uint8_t Data) + { + GCC_FORCE_POINTER_ACCESS(Buffer); + + *Buffer->In = Data; + + if (++Buffer->In == Buffer->End) + Buffer->In = Buffer->Start; + + uint_reg_t CurrentGlobalInt = GetGlobalInterruptMask(); + GlobalInterruptDisable(); + + Buffer->Count++; + + SetGlobalInterruptMask(CurrentGlobalInt); + } + + /** Removes an element from the ring buffer. + * + * \warning 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(RingBuffer_t* Buffer) ATTR_NON_NULL_PTR_ARG(1); + static inline uint8_t RingBuffer_Remove(RingBuffer_t* Buffer) + { + GCC_FORCE_POINTER_ACCESS(Buffer); + + uint8_t Data = *Buffer->Out; + + if (++Buffer->Out == Buffer->End) + Buffer->Out = Buffer->Start; + + uint_reg_t CurrentGlobalInt = GetGlobalInterruptMask(); + GlobalInterruptDisable(); + + Buffer->Count--; + + SetGlobalInterruptMask(CurrentGlobalInt); + + 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(RingBuffer_t* const Buffer) ATTR_WARN_UNUSED_RESULT ATTR_NON_NULL_PTR_ARG(1); + static inline uint8_t RingBuffer_Peek(RingBuffer_t* const Buffer) + { + return *Buffer->Out; + } + + /* Disable C linkage for C++ Compilers: */ + #if defined(__cplusplus) + } + #endif + +#endif + +/** @} */ + |