/*-
 * Copyright (c) 2021 Beckhoff Automation GmbH & Co. KG
 * Copyright (c) 2022 Bjoern A. Zeeb
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 */

#ifndef _LINUXKPI_LINUX_KFIFO_H_
#define _LINUXKPI_LINUX_KFIFO_H_

#include <sys/types.h>

#include <linux/slab.h>
#include <linux/gfp.h>

/*
 * INIT_KFIFO() is used to initialize the structure declared with
 * DECLARE_KFIFO(). It doesn't work with DECLARE_KFIFO_PTR().
 */
#define INIT_KFIFO(_kf)                                                 \
        ({                                                              \
                (_kf).total = nitems((_kf).head);                       \
                (_kf).count = 0;                                        \
                (_kf).first = 0;                                        \
                (_kf).last = 0;                                         \
        })

#define DECLARE_KFIFO(_name, _type, _size)                              \
        struct kfifo_ ## _name {                                        \
                size_t          total;                                  \
                size_t          count;                                  \
                size_t          first;                                  \
                size_t          last;                                   \
                _type           head[_size];                            \
        } _name

#define DECLARE_KFIFO_PTR(_name, _type)                                 \
        struct kfifo_ ## _name {                                        \
                size_t          total;                                  \
                size_t          count;                                  \
                size_t          first;                                  \
                size_t          last;                                   \
                _type           *head;                                  \
        } _name

#define kfifo_len(_kf)                                                  \
({                                                                      \
        (_kf)->count;                                                   \
})

#define kfifo_is_empty(_kf)                                             \
({                                                                      \
        ((_kf)->count == 0) ? true : false;                             \
})

#define kfifo_is_full(_kf)                                              \
({                                                                      \
        ((_kf)->count == (_kf)->total) ? true : false;                  \
})

#define kfifo_put(_kf, _e)                                              \
({                                                                      \
        bool _rc;                                                       \
                                                                        \
        /* Would overflow. */                                           \
        if (kfifo_is_full(_kf)) {                                       \
                _rc = false;                                            \
        } else {                                                        \
                (_kf)->head[(_kf)->last] = (_e);                        \
                (_kf)->count++;                                         \
                (_kf)->last++;                                          \
                if ((_kf)->last > (_kf)->total)                         \
                        (_kf)->last = 0;                                \
                _rc = true;                                             \
        }                                                               \
                                                                        \
        _rc;                                                            \
})

#define kfifo_get(_kf, _e)                                              \
({                                                                      \
        bool _rc;                                                       \
                                                                        \
        if (kfifo_is_empty(_kf)) {                                      \
                _rc = false;                                            \
        } else {                                                        \
                *(_e) = (_kf)->head[(_kf)->first];                      \
                (_kf)->count--;                                         \
                (_kf)->first++;                                         \
                if ((_kf)->first > (_kf)->total)                        \
                        (_kf)->first = 0;                               \
                _rc = true;                                             \
        }                                                               \
                                                                        \
        _rc;                                                            \
})

#define kfifo_alloc(_kf, _s, _gfp)                                      \
({                                                                      \
        int _error;                                                     \
                                                                        \
        (_kf)->head = kmalloc(sizeof(__typeof(*(_kf)->head)) * (_s), _gfp); \
        if ((_kf)->head == NULL)                                        \
                _error = ENOMEM;                                        \
        else {                                                          \
                (_kf)->total = (_s);                                    \
                _error = 0;                                             \
        }                                                               \
                                                                        \
        _error;                                                         \
})

#define kfifo_free(_kf)                                                 \
({                                                                      \
        kfree((_kf)->head);                                             \
        (_kf)->head = NULL;                                             \
        (_kf)->total = (_kf)->count = (_kf)->first = (_kf)->last = 0;   \
})

#endif  /* _LINUXKPI_LINUX_KFIFO_H_*/