/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Support for Intel Camera Imaging ISP subsystem.
 * Copyright (c) 2015, Intel Corporation.
 */

#ifndef _IA_CSS_CIRCBUF_DESC_H_
#define _IA_CSS_CIRCBUF_DESC_H_

#include <type_support.h>
#include <math_support.h>
#include <platform_support.h>
#include <sp.h>
#include "ia_css_circbuf_comm.h"
/****************************************************************
 *
 * Inline functions.
 *
 ****************************************************************/
/**
 * @brief Test if the circular buffer is empty.
 *
 * @param cb_desc The pointer to the circular buffer descriptor.
 *
 * @return
 *      - true when it is empty.
 *      - false when it is not empty.
 */
static inline bool ia_css_circbuf_desc_is_empty(
    ia_css_circbuf_desc_t *cb_desc)
{
        OP___assert(cb_desc);
        return (cb_desc->end == cb_desc->start);
}

/**
 * @brief Test if the circular buffer descriptor is full.
 *
 * @param cb_desc       The pointer to the circular buffer
 *                      descriptor.
 *
 * @return
 *      - true when it is full.
 *      - false when it is not full.
 */
static inline bool ia_css_circbuf_desc_is_full(
    ia_css_circbuf_desc_t *cb_desc)
{
        OP___assert(cb_desc);
        return (OP_std_modadd(cb_desc->end, 1, cb_desc->size) == cb_desc->start);
}

/**
 * @brief Initialize the circular buffer descriptor
 *
 * @param cb_desc       The pointer circular buffer descriptor
 * @param size          The size of the circular buffer
 */
static inline void ia_css_circbuf_desc_init(
    ia_css_circbuf_desc_t *cb_desc,
    int8_t size)
{
        OP___assert(cb_desc);
        cb_desc->size = size;
}

/**
 * @brief Get a position in the circular buffer descriptor.
 *
 * @param cb     The pointer to the circular buffer descriptor.
 * @param base   The base position.
 * @param offset The offset.
 *
 * @return the position in the circular buffer descriptor.
 */
static inline uint8_t ia_css_circbuf_desc_get_pos_at_offset(
    ia_css_circbuf_desc_t *cb_desc,
    u32 base,
    int offset)
{
        u8 dest;

        OP___assert(cb_desc);
        OP___assert(cb_desc->size > 0);

        /* step 1: adjust the offset  */
        while (offset < 0) {
                offset += cb_desc->size;
        }

        /* step 2: shift and round by the upper limit */
        dest = OP_std_modadd(base, offset, cb_desc->size);

        return dest;
}

/**
 * @brief Get the offset between two positions in the circular buffer
 * descriptor.
 * Get the offset from the source position to the terminal position,
 * along the direction in which the new elements come in.
 *
 * @param cb_desc       The pointer to the circular buffer descriptor.
 * @param src_pos       The source position.
 * @param dest_pos      The terminal position.
 *
 * @return the offset.
 */
static inline int ia_css_circbuf_desc_get_offset(
    ia_css_circbuf_desc_t *cb_desc,
    u32 src_pos,
    uint32_t dest_pos)
{
        int offset;

        OP___assert(cb_desc);

        offset = (int)(dest_pos - src_pos);
        offset += (offset < 0) ? cb_desc->size : 0;

        return offset;
}

/**
 * @brief Get the number of available elements.
 *
 * @param cb_desc The pointer to the circular buffer.
 *
 * @return The number of available elements.
 */
static inline uint32_t ia_css_circbuf_desc_get_num_elems(
    ia_css_circbuf_desc_t *cb_desc)
{
        int num;

        OP___assert(cb_desc);

        num = ia_css_circbuf_desc_get_offset(cb_desc,
                                             cb_desc->start,
                                             cb_desc->end);

        return (uint32_t)num;
}

/**
 * @brief Get the number of free elements.
 *
 * @param cb_desc The pointer to the circular buffer descriptor.
 *
 * @return: The number of free elements.
 */
static inline uint32_t ia_css_circbuf_desc_get_free_elems(
    ia_css_circbuf_desc_t *cb_desc)
{
        u32 num;

        OP___assert(cb_desc);

        num = ia_css_circbuf_desc_get_offset(cb_desc,
                                             cb_desc->start,
                                             cb_desc->end);

        return (cb_desc->size - num);
}
#endif /*_IA_CSS_CIRCBUF_DESC_H_ */