OpenModem/util/FIFO16.h

#ifndef UTIL_FIFO16_H
#define UTIL_FIFO16_H

#include <stdio.h>
#include <stddef.h>
#include <stdbool.h>
#include <util/atomic.h>

typedef struct FIFOBuffer16
{
  size_t *begin;
  size_t *end;
  size_t * volatile head;
  size_t * volatile tail;
} FIFOBuffer16;

inline bool fifo16_isempty(const FIFOBuffer16 *f) {
  return f->head == f->tail;
}

inline bool fifo16_isfull(const FIFOBuffer16 *f) {
  return ((f->head == f->begin) && (f->tail == f->end)) || (f->tail == f->head - 1);
}

inline void fifo16_push(FIFOBuffer16 *f, size_t c) {
  *(f->tail) = c;

  if (f->tail == f->end) {
    f->tail = f->begin;
  } else {
    f->tail++;
  }
}

inline size_t fifo16_pop(FIFOBuffer16 *f) {
  if(f->head == f->end) {
    f->head = f->begin;
    return *(f->end);
  } else {
    return *(f->head++);
  }
}

inline void fifo16_flush(FIFOBuffer16 *f) {
  f->head = f->tail;
}

static inline bool fifo16_isempty_locked(const FIFOBuffer16 *f) {
  bool result;
  ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
    result = fifo16_isempty(f);
  }
  return result;
}

static inline bool fifo16_isfull_locked(const FIFOBuffer16 *f) {
  bool result;
  ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
    result = fifo16_isfull(f);
  }
  return result;
}

static inline void fifo16_push_locked(FIFOBuffer16 *f, size_t c) {
  ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
    fifo16_push(f, c);
  }
}

static inline size_t fifo16_pop_locked(FIFOBuffer16 *f) {
  size_t c;
  ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
    c = fifo16_pop(f);
  }
  return c;
}

inline void fifo16_init(FIFOBuffer16 *f, size_t *buffer, size_t size) {
  f->head = f->tail = f->begin = buffer;
  f->end = buffer + (size/sizeof(size_t)) - 2;
}

inline size_t fifo16_len(FIFOBuffer16 *f) {
  return ((f->end - f->begin))/sizeof(size_t);
}

#endif