Projects/USBtoSerial/Lib/LightweightRingBuff.h

   1 /*
   2              LUFA Library
   3      Copyright (C) Dean Camera, 2010.
   4
   5   dean [at] fourwalledcubicle [dot] com
   6       www.fourwalledcubicle.com
   7 */
   8
   9 /*
  10   Copyright 2010  Dean Camera (dean [at] fourwalledcubicle [dot] com)
  11
  12   Permission to use, copy, modify, distribute, and sell this
  13   software and its documentation for any purpose is hereby granted
  14   without fee, provided that the above copyright notice appear in
  15   all copies and that both that the copyright notice and this
  16   permission notice and warranty disclaimer appear in supporting
  17   documentation, and that the name of the author not be used in
  18   advertising or publicity pertaining to distribution of the
  19   software without specific, written prior permission.
  20
  21   The author disclaim all warranties with regard to this
  22   software, including all implied warranties of merchantability
  23   and fitness.  In no event shall the author be liable for any
  24   special, indirect or consequential damages or any damages
  25   whatsoever resulting from loss of use, data or profits, whether
  26   in an action of contract, negligence or other tortious action,
  27   arising out of or in connection with the use or performance of
  28   this software.
  29 */
  30
  31 /** \file
  32  *
  33  *  Ultra lightweight ring buffer, for fast insertion/deletion.
  34  */
  35
  36 #ifndef _ULW_RING_BUFF_H_
  37 #define _ULW_RING_BUFF_H_
  38
  39         /* Includes: */
  40                 #include <util/atomic.h>
  41
  42                 #include <stdint.h>
  43                 #include <stdbool.h>
  44
  45         /* Defines: */
  46                 /** Size of each ring buffer, in data elements - must be between 1 and 255. */
  47                 #define BUFFER_SIZE      128
  48
  49                 /** Type of data to store into the buffer. */
  50                 #define RingBuff_Data_t  uint8_t
  51
  52         /* Type Defines: */
  53                 /** Type define for a new ring buffer object. Buffers should be initialized via a call to
  54                  *  \ref RingBuffer_InitBuffer() before use.
  55                  */
  56                 typedef struct
  57                 {
  58                         RingBuff_Data_t  Buffer[BUFFER_SIZE]; /**< Internal ring buffer data, referenced by the buffer pointers. */
  59                         RingBuff_Data_t* In; /**< Current storage location in the circular buffer */
  60                         RingBuff_Data_t* Out; /**< Current retrieval location in the circular buffer */
  61                         uint8_t          Count; /**< Total number of bytes stored in the circular buffer */
  62                 } RingBuff_t;
  63
  64         /* Inline Functions: */
  65                 /** Initializes a ring buffer ready for use. Buffers must be initialized via this function
  66                  *  before any operations are called upon them. Already initialized buffers may be reset
  67                  *  by re-initializing them using this function.
  68                  *
  69                  *  \ref Buffer  Pointer to a ring buffer structure to initialize
  70                  */
  71                 static inline void RingBuffer_InitBuffer(RingBuff_t* const Buffer)
  72                 {
  73                         Buffer->In    = Buffer->Buffer;
  74                         Buffer->Out   = Buffer->Buffer;
  75                         Buffer->Count = 0;
  76                 }
  77
  78                 /** Inserts an element into the ring buffer.
  79                  *
  80                  *  \ref Buffer  Pointer to a ring buffer structure to insert into
  81                  *  \ref Data    Data element to insert into the buffer
  82                  */
  83                 static inline void RingBuffer_Insert(RingBuff_t* const Buffer, RingBuff_Data_t Data)
  84                 {
  85                         ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
  86                         {
  87                                 *Buffer->In = Data;
  88
  89                                 if (++Buffer->In == &Buffer->Buffer[BUFFER_SIZE])
  90                                   Buffer->In = Buffer->Buffer;
  91
  92                                 Buffer->Count++;
  93                         }
  94                 }
  95
  96                 /** Retrieves an element from the ring buffer.
  97                  *
  98                  *  \ref Buffer  Pointer to a ring buffer structure to retrieve from
  99                  *
 100                  *  \return Next data element stored in the buffer
 101                  */
 102                 static inline RingBuff_Data_t RingBuffer_Remove(RingBuff_t* const Buffer)
 103                 {
 104                         RingBuff_Data_t Data;
 105
 106                         ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
 107                         {
 108                                 Data = *Buffer->Out;
 109
 110                                 if (++Buffer->Out == &Buffer->Buffer[BUFFER_SIZE])
 111                                   Buffer->Out = Buffer->Buffer;
 112
 113                                 Buffer->Count--;
 114                         }
 115
 116                         return Data;
 117                 }
 118
 119 #endif
 120