ringbuffer.h

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/* Copyright 2017 Wirepas Ltd. All Rights Reserved.
 *
 * See file LICENSE.txt for full license details.
 *
 */
 
#ifndef RINGBUFFER_H_
#define RINGBUFFER_H_
 
/*----------------------------------------------------------------------------
 Notes:
 The length of the receive and transmit buffers must be a power of 2.
 Each buffer has a next_in and a next_out index.
 If next_in = next_out, the buffer is empty.
 (next_in - next_out) % buffer_size = the number of characters in the buffer.
 *----------------------------------------------------------------------------*/
 
#if !defined BUFFER_SIZE
#error Please define BUFFER_SIZE before including this header!
#endif
 
#if BUFFER_SIZE < 2
#error BUFFER_SIZE is too small.  It must be larger than 1.
#elif ((BUFFER_SIZE & (BUFFER_SIZE-1)) != 0)
#error BUFFER_SIZE must be a power of 2.
#endif
 
#define MASK    (BUFFER_SIZE-1)
 
typedef struct
{
    uint16_t    in;                     // Next In Index
    uint16_t    out;                    // Next Out Index
    uint8_t     buf[BUFFER_SIZE];       // Buffer
} ringbuffer_t;
 
#define Ringbuffer_size(p)          (BUFFER_SIZE)
 
#define Ringbuffer_usage(p)         ((uint16_t)((p).in - (p).out))
 
#define Ringbuffer_free(p)          (Ringbuffer_size(p)-Ringbuffer_usage(p))
 
#define Ringbuffer_contents(p)      ((p).buf)
 
#define Ringbuffer_reset(p)         do{ (p).out = 0; (p).in = 0; }while(false)
 
#define Ringbuffer_isReset(p)       ((p).out == 0 && (p).in == 0)
 
#define Ringbuffer_getHeadIdx(p)    ((p).in & MASK)
 
#define Ringbuffer_getHeadByte(p)   ((p).buf[Ringbuffer_getHeadIdx(p)])
 
#define Ringbuffer_getHeadPtr(p)    (uint8_t *)(&Ringbuffer_getHeadByte(p))
 
#define Ringbuffer_incrHead(p, a)   ((p).in += (a))
 
#define Ringbuffer_getTailIdx(p)    ((p).out & MASK)
 
#define Ringbuffer_getTailByte(p)   ((p).buf[Ringbuffer_getTailIdx(p)])
 
#define Ringbuffer_getTailPtr(p)    (uint8_t *)(&Ringbuffer_getTailByte(p))
 
#define Ringbuffer_incrTail(p, a)   ((p).out += (a))
 
#endif /* RINGBUFFER_H_ */