Fixed MIDI class driver send routines silently discarding packets if the endpoint...

[pub/USBasp.git] / Projects / XPLAINBridge / Lib / LightweightRingBuff.h

diff --git a/Projects/XPLAINBridge/Lib/LightweightRingBuff.h b/Projects/XPLAINBridge/Lib/LightweightRingBuff.h
index 9c25707..0205fe4 100644 (file)
--- a/Projects/XPLAINBridge/Lib/LightweightRingBuff.h
+++ b/Projects/XPLAINBridge/Lib/LightweightRingBuff.h
@@ -1,21 +1,21 @@
 /*
              LUFA Library
      Copyright (C) Dean Camera, 2010.
 /*
              LUFA Library
      Copyright (C) Dean Camera, 2010.

-              
+

   dean [at] fourwalledcubicle [dot] com
   dean [at] fourwalledcubicle [dot] com

-      www.fourwalledcubicle.com
+           www.lufa-lib.org

 */
 
 /*
   Copyright 2010  Dean Camera (dean [at] fourwalledcubicle [dot] com)
 
 */
 
 /*
   Copyright 2010  Dean Camera (dean [at] fourwalledcubicle [dot] com)
 

-  Permission to use, copy, modify, distribute, and sell this 
+  Permission to use, copy, modify, distribute, and sell this

   software and its documentation for any purpose is hereby granted
   software and its documentation for any purpose is hereby granted

-  without fee, provided that the above copyright notice appear in 
+  without fee, provided that the above copyright notice appear in

   all copies and that both that the copyright notice and this
   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 
+  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 without specific, written prior permission.
 
   The author disclaim all warranties with regard to this


@@ -30,24 +30,40 @@
 
 /** \file
  *
 
 /** \file
  *

- *  Ultra lightweight ring buffer, for fast insertion/deletion.
+ *  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>
 #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. */
                #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
-               
+               #define BUFFER_SIZE         255
+

                /** Type of data to store into the buffer. */
                /** Type of data to store into the buffer. */

-               #define RingBuff_Data_t  uint8_t
+               #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
 
        /* Type Defines: */
                /** Type define for a new ring buffer object. Buffers should be initialized via a call to


@@ -58,9 +74,9 @@
                        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_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 */

-                       uint8_t          Count; /**< Total number of bytes stored in the circular buffer */
+                       RingBuff_Count_t Count;

                } RingBuff_t;
                } 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
        /* 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


@@ -70,68 +86,96 @@
                 */
                static inline void RingBuffer_InitBuffer(RingBuff_t* const Buffer)
                {
                 */
                static inline void RingBuffer_InitBuffer(RingBuff_t* const Buffer)
                {

-                       Buffer->In    = Buffer->Buffer;
-                       Buffer->Out   = Buffer->Buffer;
-                       Buffer->Count = 0;
+                       ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
+                       {
+                               Buffer->In  = Buffer->Buffer;
+                               Buffer->Out = Buffer->Buffer;
+                       }

                }
                }

-               
-               /** Atomically inserts an element into the ring 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.

                 *
                 *

-                *  \param[in,out] Buffer  Pointer to a ring buffer structure to insert into
-                *  \param[in]     Data    Data element to insert into the buffer
+                *  \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 void RingBuffer_AtomicInsert(RingBuff_t* const Buffer, RingBuff_Data_t Data)
+               static inline RingBuff_Count_t RingBuffer_GetCount(RingBuff_t* const Buffer)

                {
                {

+                       RingBuff_Count_t Count;
+

                        ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
                        {
                        ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
                        {

-                               *Buffer->In = Data;
-                       
-                               if (++Buffer->In == &Buffer->Buffer[BUFFER_SIZE])
-                                 Buffer->In = Buffer->Buffer;
-                                 
-                               Buffer->Count++;
+                               Count = Buffer->Count;

                        }
                        }

+
+                       return Count;

                }
 
                }
 

-               /** Atomically retrieves an element from the ring buffer.
+               /** 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 retrieve from
+                *  \param[in,out] Buffer  Pointer to a ring buffer structure to insert into

                 *
                 *

-                *  \return Next data element stored in the buffer
+                *  \return Boolean true if the buffer contains no free space, false otherwise

                 */
                 */

-               static inline RingBuff_Data_t RingBuffer_AtomicRemove(RingBuff_t* const Buffer)
+               static inline bool RingBuffer_IsFull(RingBuff_t* const Buffer)

                {
                {

-                       RingBuff_Data_t Data;
-                       
-                       ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
-                       {
-                               Data = *Buffer->Out;
-                       
-                               if (++Buffer->Out == &Buffer->Buffer[BUFFER_SIZE])
-                                 Buffer->Out = Buffer->Buffer;
-                                 
-                               Buffer->Count--;
-                       }
+                       return (RingBuffer_GetCount(Buffer) == BUFFER_SIZE);
+               }

 
 

-                       return Data;
+               /** 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.
                 *
                }
 
                /** 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
                 */
                 *  \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, RingBuff_Data_t Data)
+               static inline void RingBuffer_Insert(RingBuff_t* const Buffer,
+                                                    const RingBuff_Data_t Data)

                {
                        *Buffer->In = Data;
                {
                        *Buffer->In = Data;

-                       
+

                        if (++Buffer->In == &Buffer->Buffer[BUFFER_SIZE])
                          Buffer->In = Buffer->Buffer;
                        if (++Buffer->In == &Buffer->Buffer[BUFFER_SIZE])
                          Buffer->In = Buffer->Buffer;

-                                 
-                       Buffer->Count++;
+
+                       ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
+                       {
+                               Buffer->Count++;
+                       }

                }
 
                }
 

-               /** Retrieves an element from the ring buffer.
+               /** 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
                 *
                 *
                 *  \param[in,out] Buffer  Pointer to a ring buffer structure to retrieve from
                 *


@@ -140,14 +184,17 @@
                static inline RingBuff_Data_t RingBuffer_Remove(RingBuff_t* const Buffer)
                {
                        RingBuff_Data_t Data = *Buffer->Out;
                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;
                        if (++Buffer->Out == &Buffer->Buffer[BUFFER_SIZE])
                          Buffer->Out = Buffer->Buffer;

-                                 
-                       Buffer->Count--;
+
+                       ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
+                       {
+                               Buffer->Count--;
+                       }

 
                        return Data;
                }
 
 #endif
 
                        return Data;
                }
 
 #endif

- 
\ No newline at end of file
+