-/*\r
- LUFA Library\r
- Copyright (C) Dean Camera, 2010.\r
- \r
- dean [at] fourwalledcubicle [dot] com\r
- www.fourwalledcubicle.com\r
-*/\r
-\r
-/*\r
- Copyright 2010 Dean Camera (dean [at] fourwalledcubicle [dot] com)\r
-\r
- Permission to use, copy, modify, distribute, and sell this \r
- software and its documentation for any purpose is hereby granted\r
- without fee, provided that the above copyright notice appear in \r
- all copies and that both that the copyright notice and this\r
- permission notice and warranty disclaimer appear in supporting \r
- documentation, and that the name of the author not be used in \r
- advertising or publicity pertaining to distribution of the \r
- software without specific, written prior permission.\r
-\r
- The author disclaim all warranties with regard to this\r
- software, including all implied warranties of merchantability\r
- and fitness. In no event shall the author be liable for any\r
- special, indirect or consequential damages or any damages\r
- whatsoever resulting from loss of use, data or profits, whether\r
- in an action of contract, negligence or other tortious action,\r
- arising out of or in connection with the use or performance of\r
- this software.\r
-*/\r
-\r
-/** \file\r
- *\r
- * Ultra lightweight ring buffer, for fast insertion/deletion.\r
- */\r
- \r
-#ifndef _ULW_RING_BUFF_H_\r
-#define _ULW_RING_BUFF_H_\r
-\r
- /* Includes: */\r
- #include <stdint.h>\r
- #include <stdbool.h>\r
-\r
- /* Defines: */\r
- /** Size of each ring buffer, in bytes */\r
- #define BUFFER_SIZE 128\r
- \r
- /** Type of data to store into the buffer */\r
- #define RingBuff_Data_t uint8_t\r
-\r
- /* Type Defines: */\r
- typedef struct\r
- {\r
- RingBuff_Data_t Buffer[BUFFER_SIZE];\r
- RingBuff_Data_t* In;\r
- RingBuff_Data_t* Out;\r
- } RingBuff_t;\r
- \r
- /* Inline Functions: */\r
- static inline void RingBuffer_InitBuffer(RingBuff_t* const Buffer)\r
- {\r
- Buffer->In = Buffer->Buffer;\r
- Buffer->Out = Buffer->Buffer; \r
- }\r
- \r
- static inline void RingBuffer_Insert(RingBuff_t* const Buffer, RingBuff_Data_t Data)\r
- {\r
- *Buffer->In = Data;\r
- \r
- if (++Buffer->In == &Buffer->Buffer[BUFFER_SIZE])\r
- Buffer->In = Buffer->Buffer;\r
- }\r
-\r
- static inline RingBuff_Data_t RingBuffer_Remove(RingBuff_t* const Buffer)\r
- {\r
- RingBuff_Data_t Data = *Buffer->Out;\r
- \r
- if (++Buffer->Out == &Buffer->Buffer[BUFFER_SIZE])\r
- Buffer->Out = Buffer->Buffer;\r
- \r
- return Data;\r
- }\r
-\r
- static inline bool RingBuffer_Empty(RingBuff_t* const Buffer)\r
- {\r
- return (Buffer->In == Buffer->Out);\r
- }\r
-\r
-#endif\r
-
\ No newline at end of file
+/*
+ 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;
+ }
+
+#endif
+
projects / pub / USBasp.git / blobdiff