// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

/*
 *
 */

#ifndef CIRCULAR_BUFFER_H
#define CIRCULAR_BUFFER_H

#include "rust_globals.h"
#include "rust_kernel.h"

class
circular_buffer : public kernel_owned<circular_buffer> {
    static const size_t INITIAL_CIRCULAR_BUFFER_SIZE_IN_UNITS = 8;

public:
    rust_kernel *kernel;
    // Size of the data unit in bytes.
    const size_t unit_sz;
    circular_buffer(rust_kernel *kernel, size_t unit_sz);
    ~circular_buffer();
    void transfer(void *dst);
    void enqueue(void *src);
    void dequeue(void *dst);
    uint8_t *peek();
    bool is_empty();
    size_t size();

private:
    // private and undefined to disable copying
    circular_buffer(const circular_buffer& rhs);
    circular_buffer& operator=(const circular_buffer& rhs);
    
private:
    size_t initial_size();
    void grow();
    void shrink();

    // Size of the buffer in bytes.
    size_t _buffer_sz;

    // Byte offset within the buffer where to read the next unit of data.
    size_t _next;

    // Number of bytes that have not been read from the buffer.
    size_t _unread;

    // The buffer itself.
    uint8_t *_buffer;
};

//
// Local Variables:
// mode: C++
// fill-column: 78;
// indent-tabs-mode: nil
// c-basic-offset: 4
// buffer-file-coding-system: utf-8-unix
// compile-command: "make -k -C $RBUILD 2>&1 | sed -e 's/\\/x\\//x:\\//g'";
// End:
//

#endif /* CIRCULAR_BUFFER_H */