+++ /dev/null
-/*
- 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
- *
- * Ultra lightweight ring buffer, for fast insertion/deletion. This uses inlined functions
- * for maximum speed. All buffers created with this library must be of the same size, however
- * multiple independant buffers can be created.
- *
- * 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.
- */
-
-#ifndef _ULW_RING_BUFF_H_
-#define _ULW_RING_BUFF_H_
-
- /* Includes: */
- #include <util/atomic.h>
-
- #include <stdint.h>
- #include <stdbool.h>
-
- /* Defines: */
- /** Size of each ring buffer, in data elements - must be between 1 and 255. */
- #define BUFFER_SIZE 255
-
- /** Type of data to store into the buffer. */
- #define RingBuff_Data_t uint8_t
-
- /** Datatype which may be used to store the count of data stored in a buffer, retrieved
- * via a call to \ref RingBuffer_GetCount().
- */
- #if (BUFFER_SIZE <= 0xFF)
- #define RingBuff_Count_t uint8_t
- #else
- #define RingBuff_Count_t uint16_t
- #endif
-
- /* 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
- {
- RingBuff_Data_t Buffer[BUFFER_SIZE]; /**< Internal ring buffer data, referenced by the buffer pointers. */
- RingBuff_Data_t* In; /**< Current storage location in the circular buffer */
- RingBuff_Data_t* Out; /**< Current retrieval location in the circular buffer */
- RingBuff_Count_t Count;
- } 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
- */
- static inline void RingBuffer_InitBuffer(RingBuff_t* const Buffer)
- {
- ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
- {
- Buffer->In = Buffer->Buffer;
- Buffer->Out = Buffer->Buffer;
- }
- }
-
- /** 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 RingBuff_Count_t RingBuffer_GetCount(RingBuff_t* const Buffer)
- {
- RingBuff_Count_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 RingBuff_Data_t Data)
- {
- *Buffer->In = Data;
-
- if (++Buffer->In == &Buffer->Buffer[BUFFER_SIZE])
- Buffer->In = Buffer->Buffer;
-
- 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 RingBuff_Data_t RingBuffer_Remove(RingBuff_t* const Buffer)
- {
- RingBuff_Data_t Data = *Buffer->Out;
-
- if (++Buffer->Out == &Buffer->Buffer[BUFFER_SIZE])
- Buffer->Out = Buffer->Buffer;
-
- 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 RingBuff_Data_t RingBuffer_Peek(RingBuff_t* const Buffer)
- {
- return *Buffer->Out;
- }
-
-#endif
-
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