/*
* ringbuf.h
* ---------
* Ring buffers for more reliable UART receives.
*
* Copyright (c) 2016, NORDUnet A/S All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of the NORDUnet nor the names of its contributors may
* be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef RINGBUF_SIZE
#define RINGBUF_SIZE 256
#endif
typedef struct {
int ridx;
volatile int widx;
uint8_t buf[RINGBUF_SIZE];
} ringbuf_t;
inline void ringbuf_init(ringbuf_t *rb)
{
memset(rb, 0, sizeof(*rb));
}
inline int ringbuf_read_char(ringbuf_t *rb, uint8_t *c)
{
if (rb->ridx != rb->widx) {
*c = rb->buf[rb->ridx];
if (++rb->ridx >= sizeof(rb->buf))
rb->ridx = 0;
return 1;
}
return 0;
}
inline void ringbuf_write_char(ringbuf_t *rb, uint8_t c)
{
rb->buf[rb->widx] = c;
if (++rb->widx >= sizeof(rb->buf))
rb->widx = 0;
}
inline int ringbuf_empty(ringbuf_t *rb)
{
return (rb->ridx == rb->widx);
}
inline int ringbuf_count(ringbuf_t *rb)
{
int len = rb->widx - rb->ridx;
if (len < 0)
len += sizeof(rb->buf);
return len;
}
