libpd-sys 0.3.4

/*
 * Copyright (c) 2012 Peter Brinkmann (peter.brinkmann@gmail.com)
 *
 * For information on usage and redistribution, and for a DISCLAIMER OF ALL
 * WARRANTIES, see the file, "LICENSE.txt," in this distribution.
 *
 * See https://github.com/libpd/libpd/wiki for documentation
 *
 */

#ifndef __Z_RING_BUFFER_H__
#define __Z_RING_BUFFER_H__

#include "m_private_utils.h"

/// simple lock-free ring buffer implementation for one writer thread
/// and one consumer thread
typedef struct ring_buffer {
    int size;
    char *buf_ptr;
    atomic_int write_idx;
    atomic_int read_idx;
} ring_buffer;

/// create a ring buffer, size must be a multiple of 256
/// returns NULL on failure
ring_buffer *rb_create(int size);

/// free a ring buffer
void rb_free(ring_buffer *buffer);

/// get the number of bytes that can currently be written
/// this is safe to call from any thread
int rb_available_to_write(ring_buffer *buffer);

/// get the number of bytes that can currently be read
/// this is safe to called from any thread
int rb_available_to_read(ring_buffer *buffer);

/// write bytes from n sources to the ring buffer (if the ring buffer has
/// enough space), varargs are pairs of type (const char*, int) giving a pointer
/// to a buffer and the number of bytes to be copied
/// note: call this from a single writer thread only
/// returns 0 on success
int rb_write_to_buffer(ring_buffer *buffer, int n, ...);

/// writes single byte value n times to the ring buffer (if the ring buffer has
/// enough space)
/// note: call this from a single writer thread only
/// returns 0 on success
int rb_write_value_to_buffer(ring_buffer *buffer, int value, int n);

/// read given number of bytes from the ring buffer to dest (if the ring
/// buffer has enough data)
/// note: call this from a single reader thread only
/// returns 0 on success
int rb_read_from_buffer(ring_buffer *buffer, char *dest, int len);

/// clears the contents of the ring buffer
/// this is safe to call from any thread
void rb_clear_buffer(ring_buffer *buffer);

#endif