ring_buf.h

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/*
 * SPDX-License-Identifier: MIT
 * SPDX-FileCopyrightText: 2024, Roy Ratcliffe, Northumberland, United Kingdom
 */
#ifndef __RING_BUF_H__
#define __RING_BUF_H__
 
#ifdef __cplusplus
extern "C" {
#endif
 
#include <errno.h>
#include <stdbool.h>
#include <stddef.h>
 
#ifndef EMSGSIZE
#define EMSGSIZE 115
#endif
 
typedef ptrdiff_t ring_buf_ptrdiff_t;
 
typedef size_t ring_buf_size_t;
 
#define RING_BUF_SIZE_MAX ((ring_buf_size_t)PTRDIFF_MIN)
 
struct ring_buf_zone {
  ring_buf_ptrdiff_t base;
 
  ring_buf_ptrdiff_t head;
 
  ring_buf_ptrdiff_t tail;
};
 
struct ring_buf {
  void *space;
 
  ring_buf_size_t size;
 
  struct ring_buf_zone put;
 
  struct ring_buf_zone get;
};
 
static inline ring_buf_size_t ring_buf_used_space(const struct ring_buf *buf) {
  return buf->put.tail - buf->get.head;
}
 
static inline bool ring_buf_is_empty(const struct ring_buf *buf) {
  return ring_buf_used_space(buf) == 0U;
}
 
static inline ring_buf_size_t ring_buf_free_space(const struct ring_buf *buf) {
  return buf->size - (buf->put.head - buf->get.tail);
}
 
static inline bool ring_buf_is_full(const struct ring_buf *buf) {
  return ring_buf_free_space(buf) == 0U;
}
 
void ring_buf_reset(struct ring_buf *buf, ring_buf_ptrdiff_t base);
 
ring_buf_size_t ring_buf_put_claim(struct ring_buf *buf, void **space,
                                   ring_buf_size_t size);
 
int ring_buf_put_ack(struct ring_buf *buf, ring_buf_size_t size);
 
ring_buf_size_t ring_buf_get_claim(struct ring_buf *buf, void **space,
                                   ring_buf_size_t size);
 
int ring_buf_get_ack(struct ring_buf *buf, ring_buf_size_t size);
 
ring_buf_size_t ring_buf_put(struct ring_buf *buf, const void *data,
                             ring_buf_size_t size);
 
ring_buf_size_t ring_buf_get(struct ring_buf *buf, void *data,
                             ring_buf_size_t size);
 
int ring_buf_put_all(struct ring_buf *buf, const void *data,
                     ring_buf_size_t size);
 
int ring_buf_get_all(struct ring_buf *buf, void *data, ring_buf_size_t size);
 
#include <stdint.h>
 
#define RING_BUF_DEFINE_STATIC(_name_, _size_)                                 \
  static uint8_t _ring_buf_space_##_name_[_size_];                             \
  static struct ring_buf _name_ = {.space = _ring_buf_space_##_name_,          \
                                   .size = _size_}
 
#ifdef __cplusplus
}
#endif
 
#endif /* __RING_BUF_H__ */