Boot Linux faster!

Check our new training course

Boot Linux faster!

Check our new training course
and Creative Commons CC-BY-SA
lecture and lab materials

Bootlin logo

Elixir Cross Referencer

/** @file
 *  @brief Byte order helpers.
 */

/*
 * Copyright (c) 2015-2016, Intel Corporation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <stdint.h>

/* Internal helpers only used by the sys_* APIs further below */
#define __bswap_16(x) ((uint16_t) ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8)))
#define __bswap_32(x) ((uint32_t) ((((x) >> 24) & 0xff) | \
				   (((x) >> 8) & 0xff00) | \
				   (((x) & 0xff00) << 8) | \
				   (((x) & 0xff) << 24)))

/** @def sys_le16_to_cpu
 *  @brief Convert 16-bit integer from little-endian to host endianness.
 *
 *  @param val 16-bit integer in little-endian format.
 *
 *  @return 16-bit integer in host endianness.
 */

/** @def sys_cpu_to_le16
 *  @brief Convert 16-bit integer from host endianness to little-endian.
 *
 *  @param val 16-bit integer in host endianness.
 *
 *  @return 16-bit integer in little-endian format.
 */

/** @def sys_be16_to_cpu
 *  @brief Convert 16-bit integer from big-endian to host endianness.
 *
 *  @param val 16-bit integer in big-endian format.
 *
 *  @return 16-bit integer in host endianness.
 */

/** @def sys_cpu_to_be16
 *  @brief Convert 16-bit integer from host endianness to big-endian.
 *
 *  @param val 16-bit integer in host endianness.
 *
 *  @return 16-bit integer in big-endian format.
 */

/** @def sys_le32_to_cpu
 *  @brief Convert 32-bit integer from little-endian to host endianness.
 *
 *  @param val 32-bit integer in little-endian format.
 *
 *  @return 32-bit integer in host endianness.
 */

/** @def sys_cpu_to_le32
 *  @brief Convert 32-bit integer from host endianness to little-endian.
 *
 *  @param val 32-bit integer in host endianness.
 *
 *  @return 32-bit integer in little-endian format.
 */

/** @def sys_be32_to_cpu
 *  @brief Convert 32-bit integer from big-endian to host endianness.
 *
 *  @param val 32-bit integer in big-endian format.
 *
 *  @return 32-bit integer in host endianness.
 */

/** @def sys_cpu_to_be32
 *  @brief Convert 32-bit integer from host endianness to big-endian.
 *
 *  @param val 32-bit integer in host endianness.
 *
 *  @return 32-bit integer in big-endian format.
 */

#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
#define sys_le16_to_cpu(val) (val)
#define sys_cpu_to_le16(val) (val)
#define sys_be16_to_cpu(val) __bswap_16(val)
#define sys_cpu_to_be16(val) __bswap_16(val)
#define sys_le32_to_cpu(val) (val)
#define sys_cpu_to_le32(val) (val)
#define sys_be32_to_cpu(val) __bswap_32(val)
#define sys_cpu_to_be32(val) __bswap_32(val)
#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
#define sys_le16_to_cpu(val) __bswap_16(val)
#define sys_cpu_to_le16(val) __bswap_16(val)
#define sys_be16_to_cpu(val) (val)
#define sys_cpu_to_be16(val) (val)
#define sys_le32_to_cpu(val) __bswap_32(val)
#define sys_cpu_to_le32(val) __bswap_32(val)
#define sys_be32_to_cpu(val) (val)
#define sys_cpu_to_be32(val) (val)
#else
#error "Unknown byte order"
#endif

/**
 *  @brief Put a 16-bit intger as big-endian to arbitrary location.
 *
 *  Put a 16-bit integer, originally in host endianness, to a
 *  potentially unaligned memory location in big-endian format.
 *
 *  @param val 16-bit integer in host endianness.
 *  @param dst Destination memory address to store the result.
 */
static inline void sys_put_be16(uint16_t val, uint8_t dst[2])
{
	dst[0] = val >> 8;
	dst[1] = val;
}

/**
 *  @brief Put a 32-bit intger as big-endian to arbitrary location.
 *
 *  Put a 32-bit integer, originally in host endianness, to a
 *  potentially unaligned memory location in big-endian format.
 *
 *  @param val 32-bit integer in host endianness.
 *  @param dst Destination memory address to store the result.
 */
static inline void sys_put_be32(uint32_t val, uint8_t dst[4])
{
	sys_put_be16(val >> 16, dst);
	sys_put_be16(val, &dst[2]);
}

/**
 *  @brief Put a 16-bit intger as little-endian to arbitrary location.
 *
 *  Put a 16-bit integer, originally in host endianness, to a
 *  potentially unaligned memory location in little-endian format.
 *
 *  @param val 16-bit integer in host endianness.
 *  @param dst Destination memory address to store the result.
 */
static inline void sys_put_le16(uint16_t val, uint8_t dst[2])
{
	dst[0] = val;
	dst[1] = val >> 8;
}

/**
 *  @brief Put a 32-bit intger as little-endian to arbitrary location.
 *
 *  Put a 32-bit integer, originally in host endianness, to a
 *  potentially unaligned memory location in little-endian format.
 *
 *  @param val 32-bit integer in host endianness.
 *  @param dst Destination memory address to store the result.
 */
static inline void sys_put_le32(uint32_t val, uint8_t dst[4])
{
	sys_put_le16(val, dst);
	sys_put_le16(val >> 16, &dst[2]);
}

/**
 *  @brief Get a 16-bit intger stored in big-endian format.
 *
 *  Get a 16-bit integer, stored in big-endian format in a potentially
 *  unaligned memory location, and convert it to the host endianness.
 *
 *  @param src Location of the big-endian 16-bit integer to get.
 *
 *  @return 16-bit integer in host endianness.
 */
static inline uint16_t sys_get_be16(const uint8_t src[2])
{
	return ((uint16_t)src[0] << 8) | src[1];
}

/**
 *  @brief Get a 32-bit intger stored in big-endian format.
 *
 *  Get a 32-bit integer, stored in big-endian format in a potentially
 *  unaligned memory location, and convert it to the host endianness.
 *
 *  @param src Location of the big-endian 32-bit integer to get.
 *
 *  @return 32-bit integer in host endianness.
 */
static inline uint32_t sys_get_be32(const uint8_t src[4])
{
	return ((uint32_t)sys_get_be16(&src[0]) << 16) | sys_get_be16(&src[2]);
}

/**
 *  @brief Get a 16-bit intger stored in little-endian format.
 *
 *  Get a 16-bit integer, stored in little-endian format in a potentially
 *  unaligned memory location, and convert it to the host endianness.
 *
 *  @param src Location of the little-endian 16-bit integer to get.
 *
 *  @return 16-bit integer in host endianness.
 */
static inline uint16_t sys_get_le16(const uint8_t src[2])
{
	return ((uint16_t)src[1] << 8) | src[0];
}

/**
 *  @brief Get a 32-bit intger stored in little-endian format.
 *
 *  Get a 32-bit integer, stored in little-endian format in a potentially
 *  unaligned memory location, and convert it to the host endianness.
 *
 *  @param src Location of the little-endian 32-bit integer to get.
 *
 *  @return 32-bit integer in host endianness.
 */
static inline uint32_t sys_get_le32(const uint8_t src[4])
{
	return ((uint32_t)sys_get_le16(&src[2]) << 16) | sys_get_le16(&src[0]);
}