u_index_fifo.h

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// Copyright 2020-2023, Collabora, Ltd.
// SPDX-License-Identifier: BSL-1.0
/*!
 * @file
 * @brief  A FIFO for indices.
 * @author Jakob Bornecrantz <jakob@collabora.com>
 * @ingroup aux_util
 */
 
#pragma once
 
#include "xrt/xrt_compiler.h"
 
#include <stdint.h>
#include <stddef.h>
 
 
#define U_MAX_FIFO_INDICES 16
 
struct u_index_fifo
{
        uint32_t indices[U_MAX_FIFO_INDICES];
        size_t start;
        size_t end;
};
 
static inline int
u_index_fifo_is_empty(struct u_index_fifo *uif)
{
        if (uif->start == uif->end) {
                return 1;
        }
        return 0;
}
 
static inline int
u_index_fifo_is_full(struct u_index_fifo *uif)
{
        if (((uif->end + 1) % U_MAX_FIFO_INDICES) == uif->start) {
                return 1;
        }
        return 0;
}
 
static inline int
u_index_fifo_peek(struct u_index_fifo *uif, uint32_t *out_index)
{
        if (u_index_fifo_is_empty(uif)) {
                return -1;
        }
 
        *out_index = uif->indices[uif->start];
        return 0;
}
 
static inline int
u_index_fifo_pop(struct u_index_fifo *uif, uint32_t *out_index)
{
        if (u_index_fifo_is_empty(uif)) {
                return -1;
        }
 
        *out_index = uif->indices[uif->start];
        uif->start = (uif->start + 1) % U_MAX_FIFO_INDICES;
        return 0;
}
 
static inline int
u_index_fifo_push(struct u_index_fifo *uif, uint32_t index)
{
        if (u_index_fifo_is_full(uif)) {
                return -1;
        }
 
        uif->indices[uif->end] = index;
        uif->end = (uif->end + 1) % U_MAX_FIFO_INDICES;
 
        return 0;
}