bit_rev.h

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/*
 * SPDX-FileCopyrightText: Copyright The Zephyr Project Contributors
 *
 * SPDX-License-Identifier: Apache-2.0
 */
 
#ifndef ZEPHYR_INCLUDE_SYS_BIT_REV_H_
#define ZEPHYR_INCLUDE_SYS_BIT_REV_H_
 
#include <zephyr/toolchain.h>
#include <zephyr/arch/cpu.h>
#include <zephyr/types.h>
#include <zephyr/sys/util.h>
 
#ifdef __cplusplus
extern "C" {
#endif


static inline uint32_t sys_bit_rev32(uint32_t x)
{
#if HAS_BUILTIN(__builtin_bitreverse32)
        return __builtin_bitreverse32(x);
#elif defined(CONFIG_ARCH_HAS_BIT_REV)
        return arch_sys_bit_rev32(x);
#else
        x = ((x >> 1) & 0x55555555) | ((x & 0x55555555) << 1);
        x = ((x >> 2) & 0x33333333) | ((x & 0x33333333) << 2);
        x = ((x >> 4) & 0x0F0F0F0F) | ((x & 0x0F0F0F0F) << 4);
        x = ((x >> 8) & 0x00FF00FF) | ((x & 0x00FF00FF) << 8);
        return (x >> 16) | (x << 16);
#endif /* HAS_BUILTIN(__builtin_bitreverse32) */
}

static inline uint16_t sys_bit_rev16(uint16_t x)
{
#if HAS_BUILTIN(__builtin_bitreverse16)
        return __builtin_bitreverse16(x);
#elif defined(CONFIG_ARCH_HAS_BIT_REV)
        return arch_sys_bit_rev16(x);
#else
        x = ((x >> 1) & 0x5555) | ((x & 0x5555) << 1);
        x = ((x >> 2) & 0x3333) | ((x & 0x3333) << 2);
        x = ((x >> 4) & 0x0F0F) | ((x & 0x0F0F) << 4);
        return (x >> 8) | (x << 8);
#endif /* HAS_BUILTIN(__builtin_bitreverse16) */
}

static inline uint8_t sys_bit_rev8(uint8_t x)
{
#if HAS_BUILTIN(__builtin_bitreverse8)
        return __builtin_bitreverse8(x);
#elif defined(CONFIG_ARCH_HAS_BIT_REV)
        return arch_sys_bit_rev8(x);
#else
        x = ((x >> 1) & 0x55) | ((x & 0x55) << 1);
        x = ((x >> 2) & 0x33) | ((x & 0x33) << 2);
        return (x >> 4) | (x << 4);
#endif /* HAS_BUILTIN(__builtin_bitreverse8) */
}

 
#ifdef __cplusplus
}
#endif
 
#endif /* ZEPHYR_INCLUDE_SYS_BIT_REV_H_ */