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 a4b0f8b..768e49a 100644 (file)
--- a/Projects/Benito/Lib/LightweightRingBuff.h
+++ b/Projects/Benito/Lib/LightweightRingBuff.h
@@ -30,61 +30,170 @@
 
 /** \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: */
  */
  
 #ifndef _ULW_RING_BUFF_H_
 #define _ULW_RING_BUFF_H_
 
        /* Includes: */

+               #include <util/atomic.h>
+       

                #include <stdint.h>
                #include <stdbool.h>
 
        /* Defines: */
                #include <stdint.h>
                #include <stdbool.h>
 
        /* Defines: */

-               /** Size of each ring buffer, in bytes. */
-               #define BUFFER_SIZE      128
+               /** 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. */
                
                /** 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 Defines: */

+               /** Type define for a new ring buffer object. Buffers should be initialized via a call to
+                *  \ref RingBuffer_InitBuffer() before use.
+                */

                typedef struct
                {
                typedef struct
                {

-                       RingBuff_Data_t  Buffer[BUFFER_SIZE];
-                       RingBuff_Data_t* In;
-                       RingBuff_Data_t* Out;
-                       uint8_t          Count;
+                       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: */
                } 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)
                {
                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;
+                       }

                }
                
                }
                

-               static inline void RingBuffer_Insert(RingBuff_t* const Buffer, RingBuff_Data_t Data)
+               /** 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)

                {
                {

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

-                         
-                       Buffer->Count++;
+
+                       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;
                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