Reduced HOST_DEVICE_SETTLE_DELAY_MS to 1000ms down from 1500ms to improve device...

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

diff --git a/Projects/Benito/Lib/LightweightRingBuff.h b/Projects/Benito/Lib/LightweightRingBuff.h
index 55af753..768e49a 100644 (file)
--- a/Projects/Benito/Lib/LightweightRingBuff.h
+++ b/Projects/Benito/Lib/LightweightRingBuff.h
@@ -30,7 +30,14 @@
 
 /** \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_
  */
  
 #ifndef _ULW_RING_BUFF_H_


@@ -44,10 +51,19 @@
 
        /* Defines: */
                /** Size of each ring buffer, in data elements - must be between 1 and 255. */
 
        /* Defines: */
                /** Size of each ring buffer, in data elements - must be between 1 and 255. */

-               #define BUFFER_SIZE      128
+               #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


@@ -58,7 +74,7 @@
                        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;
        
        /* Inline Functions: */
                } RingBuff_t;
        
        /* Inline Functions: */


@@ -70,30 +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;
+                       }
+               }
+               
+               /** 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.
                 *
                /** 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;
+                       
+                       if (++Buffer->In == &Buffer->Buffer[BUFFER_SIZE])
+                         Buffer->In = Buffer->Buffer;
+

                        ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
                        {
                        ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
                        {

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

                                Buffer->Count++;
                        }
                }
 
                                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
                 *


@@ -101,20 +183,17 @@
                 */
                static inline RingBuff_Data_t RingBuffer_Remove(RingBuff_t* const Buffer)
                {
                 */
                static inline RingBuff_Data_t RingBuffer_Remove(RingBuff_t* const Buffer)
                {

-                       RingBuff_Data_t Data;
+                       RingBuff_Data_t Data = *Buffer->Out;

                        
                        

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

                        ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
                        {
                        ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
                        {

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

                                Buffer->Count--;
                        }
                                Buffer->Count--;
                        }

-
+                       

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

- 
\ No newline at end of file