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/*
* (C) Copyright 2014 Leo C. <erbl259-lmu@yahoo.de>
*
* SPDX-License-Identifier: GPL-2.0+
*/
#ifndef RING_H
#define RING_H
struct ring {
uint8_t *data;
uint_fast8_t mask;
volatile uint_fast8_t begin;
volatile uint_fast8_t end;
};
static inline
void ring_init(struct ring *ring, uint8_t *buf, int size)
{
ring->data = buf;
ring->mask = (size-1) & 0xff;
ring->begin = 0;
ring->end = 0;
}
static inline
int ring_write_ch(struct ring *ring, uint8_t ch)
{
uint_fast8_t ep = ring->end;
ring->data[ep] = ch;
ep = (ep + 1) & ring->mask;
if ((ep) != ring->begin) {
ring->end = ep;
return 1;
}
return -1;
}
#if 0
static inline
int ring_write(struct ring *ring, uint8_t *data, int size)
{
int i;
for (i = 0; i < size; i++) {
if (ring_write_ch(ring, data[i]) < 0)
return -i;
}
return i;
}
#endif
static inline
int ring_read_ch(struct ring *ring)
{
int ret = -1;
uint_fast8_t bp = ring->begin;
if (bp != ring->end) {
ret = ring->data[bp];
ring->begin = (bp + 1) & ring->mask;
}
return ret;
}
static inline
int_fast8_t ring_is_empty(struct ring *ring)
{
return ring->begin == ring->end;
}
#endif /* RING_H */
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