ringbuf/ringbuf.h

/* SPDX-License-Identifier: MIT */

#pragma once

#ifndef rb_size_t
#define rb_size_t int
#endif

/** Signatures of generic functions */
typedef void *(*ALLOC_T)(rb_size_t);
typedef void *(*MEMCPY_T)(void *, const void *, rb_size_t);

/**
 * Ring buffer, also known as circular buffer.
 */
struct RingBuf {
  rb_size_t struct_size; /* Size of the struct */
  rb_size_t capacity;    /* The physical capacity of the entire ringbuf */
  rb_size_t size;        /* The current size of the ring buffer */
  rb_size_t count;       /* The number of elements in the buffer */
  void     *write_head;  /* Address of the write head */
  void     *read_head;   /* Address of the read head */
  void     *buffer;      /* The actual data */
  void     *buffer_end;  /* The end of the buffer */
} __attribute__((packed));

// TODO: Perhaps unify these to RBResult?

enum WriteResult { Full, WriteOk }; /** Result of a write */
enum ReadResult { Empty, ReadOk };  /** Result of a read */

/** Initialize the ring buffer */
void rb_init(struct RingBuf *rb, rb_size_t capacity, void *(*alloc)(rb_size_t),
             rb_size_t struct_size);

/** Insert data to the ring buffer */
enum WriteResult rb_push_back(struct RingBuf *rb, const void *item,
                              MEMCPY_T memcpy_fn);

/** Read data from the ring buffer */
enum ReadResult rb_pop_front(struct RingBuf *rb, void *item);

/** Free the ring buffer */
void rb_destroy(struct RingBuf *rb, void(free)());