rte_sched_common.h

/* SPDX-License-Identifier: BSD-3-Clause
 * Copyright(c) 2010-2014 Intel Corporation
 */

#ifndef __INCLUDE_RTE_SCHED_COMMON_H__
#define __INCLUDE_RTE_SCHED_COMMON_H__

#ifdef __cplusplus
extern "C" {
#endif

#include <stdint.h>
#include <sys/types.h>

#if 0
static inline uint32_t
rte_min_pos_4_u16(uint16_t *x)
{
    uint32_t pos0, pos1;

    pos0 = (x[0] <= x[1])? 0 : 1;
    pos1 = (x[2] <= x[3])? 2 : 3;

    return (x[pos0] <= x[pos1])? pos0 : pos1;
}

#else

/* simplified version to remove branches with CMOV instruction */
static inline uint32_t
rte_min_pos_4_u16(uint16_t *x)
{
    uint32_t pos0 = 0;
    uint32_t pos1 = 2;

    if (x[1] <= x[0]) pos0 = 1;
    if (x[3] <= x[2]) pos1 = 3;
    if (x[pos1] <= x[pos0]) pos0 = pos1;

    return pos0;
}

#endif

/*
 * Compute the Greatest Common Divisor (GCD) of two numbers.
 * This implementation uses Euclid's algorithm:
 *    gcd(a, 0) = a
 *    gcd(a, b) = gcd(b, a mod b)
 */
static inline uint64_t
rte_get_gcd64(uint64_t a, uint64_t b)
{
    uint64_t c;

    if (a == 0)
        return b;
    if (b == 0)
        return a;

    if (a < b) {
        c = a;
        a = b;
        b = c;
    }

    while (b != 0) {
        c = a % b;
        a = b;
        b = c;
    }

    return a;
}

/*
 * 32-bit version of Greatest Common Divisor (GCD).
 */
static inline uint32_t
rte_get_gcd(uint32_t a, uint32_t b)
{
    return rte_get_gcd64(a, b);
}

/*
 * Compute the Lowest Common Denominator (LCD) of two numbers.
 * This implementation computes GCD first:
 *    LCD(a, b) = (a * b) / GCD(a, b)
 */
static inline uint32_t
rte_get_lcd(uint32_t a, uint32_t b)
{
    return (a * b) / rte_get_gcd(a, b);
}

#ifdef __cplusplus
}
#endif

#endif /* __INCLUDE_RTE_SCHED_COMMON_H__ */