sta-core/include/sta/endian.hpp

/**
 * @file
 * @brief Helper macros for managing endian handling.
 */
#ifndef STA_CORE_ENDIAN_HPP
#define STA_CORE_ENDIAN_HPP


#include <sta/config.hpp>

#if !defined(STA_MCU_BIG_ENDIAN) && !defined(STA_MCU_LITTLE_ENDIAN)
#  error "Endian-ness unknown. Please specify in <sta/config.hpp>"
#endif // !STA_MCU_BIG_ENDIAN && !STA_MCU_LITTLE_ENDIAN


/**
 * @defgroup sta_core_endian Endian
 * @ingroup sta_core
 * @brief Endian handling.
 * @{
 */


/**
 * @brief Get 16-bit value with swapped byte order.
 *
 * @param u16   16-bit input value
 * @return      16-bit value w/ swapped byte order
 */
#define STA_UINT16_SWAP_BYTE_ORDER(u16) \
    ( \
        ((u16 & 0x00FF) << 8) \
      | ((u16 & 0xFF00) >> 8) \
    )

/**
 * @brief Get 32-bit value with swapped byte order.
 *
 * @param u32   32-bit input value
 * @return      32-bit value w/ swapped byte order
 */
#define STA_UINT32_SWAP_BYTE_ORDER(u32) \
    ( \
        ((u32 & 0x000000FF) << 24) \
      | ((u32 & 0x0000FF00) << 8) \
      | ((u32 & 0x00FF0000) >> 8) \
      | ((u32 & 0xFF000000) >> 24) \
    )

/**
 * @brief Get initializer list for byte array with big-endian byte order from 16-bit value.
 *
 * @param u16   16-bit input value
 * @return      Initializer list for uint8_t[2]
 */
#define STA_UINT16_TO_BYTES_BE(u16) \
    { \
        static_cast<uint8_t>(u16 >> 8), \
        static_cast<uint8_t>(u16) \
    }

/**
 * @brief Get initializer list for byte array with little-endian byte order from 16-bit value.
 *
 * @param u16   16-bit input value
 * @return      Initializer list for uint8_t[2]
 */
#define STA_UINT16_TO_BYTES_LE(u16) \
    { \
        static_cast<uint8_t>(u16), \
        static_cast<uint8_t>(u16 >> 8) \
    }

/**
 * @brief Get initializer list for byte array with big-endian byte order from 32-bit value.
 *
 * @param u32   32-bit input value
 * @return      Initializer list for uint8_t[4]
 */
#define STA_UINT32_TO_BYTES_BE(u32) \
    { \
        static_cast<uint8_t>(u32 >> 24), \
        static_cast<uint8_t>(u32 >> 16), \
        static_cast<uint8_t>(u32 >> 8), \
        static_cast<uint8_t>(u32) \
    }

/**
 * @brief Get initializer list for byte array with little-endian byte order from 32-bit value.
 *
 * @param u32   32-bit input value
 * @return      Initializer list for uint8_t[4]
 */
#define STA_UINT32_TO_BYTES_LE(u32) \
    { \
        static_cast<uint8_t>(u32), \
        static_cast<uint8_t>(u32 >> 8), \
        static_cast<uint8_t>(u32 >> 16), \
        static_cast<uint8_t>(u32 >> 24) \
    }


/**
 * @def STA_UINT16_TO_BE(u16)
 * @brief Convert 16-bit value to big-endian byte order.
 *
 * @param u16   16-bit input value
 * @return      16-bit value w/ big-endian byte order
 */

/**
 * @def STA_UINT16_TO_LE(u16)
 * @brief Convert 16-bit value to little-endian byte order.
 *
 * @param u16   16-bit input value
 * @return      16-bit value w/ little-endian byte order
 */

/**
 * @def STA_UINT16_TO_BYTES(u16)
 * @brief Get initializer list for byte array w/ MCU byte order from 16-bit value.
 *
 * @param u16   16-bit input value
 * @return      Initializer list for uint8_t[2]
 */

/**
 * @def STA_UINT16_TO_BYTES_SWAP(u16)
 * @brief Get initializer list for byte array w/ swapped MCU byte order from 16-bit value.
 *
 * @param u16   16-bit input value
 * @return      Initializer list for uint8_t[2]
 */

/**
 * @def STA_UINT32_TO_BE(u32)
 * @brief Convert 32-bit value to big-endian byte order.
 *
 * @param u32   32-bit input value
 * @return      32-bit value w/ big-endian byte order
 */

/**
 * @def STA_UINT32_TO_LE(u32)
 * @brief Convert 32-bit value to little-endian byte order.
 *
 * @param u32   32-bit input value
 * @return      32-bit value w/ little-endian byte order
 */

/**
 * @def STA_UINT32_TO_BYTES(u32)
 * @brief Get initializer list for byte array from 32-bit value.
 *
 * @param u32   32-bit input value
 * @return      Initializer list for uint8_t[4]
 */

/**
 * @def STA_UINT32_TO_BYTES_SWAP(u32)
 * @brief Get initializer list for byte array w/ swapped byte order from 32-bit value.
 *
 * @param u32   32-bit input value
 * @return      Initializer list for uint8_t[4]
 */


/** @} */


#ifdef STA_MCU_LITTLE_ENDIAN

#  define STA_UINT16_TO_BE(u16)             STA_UINT16_SWAP_BYTE_ORDER(u16)
#  define STA_UINT16_TO_LE(u16)             (u16)
#  define STA_UINT16_TO_BYTES(u16)          STA_UINT16_TO_BYTES_LE(u16)
#  define STA_UINT16_TO_BYTES_SWAP(u16)     STA_UINT16_TO_BYTES_BE(u16)

#  define STA_UINT32_TO_BE(u32)             STA_UINT32_SWAP_BYTE_ORDER(u32)
#  define STA_UINT32_TO_LE(u32)             (u32)
#  define STA_UINT32_TO_BYTES(u32)          STA_UINT32_TO_BYTES_LE(u32)
#  define STA_UINT32_TO_BYTES_SWAP(u32)     STA_UINT32_TO_BYTES_BE(u32)

#else // STA_MCU_BIG_ENDIAN

#  define STA_UINT16_TO_BE(u16)             (u16)
#  define STA_UINT16_TO_LE(u16)             STA_UINT16_SWAP_BYTE_ORDER(u16)
#  define STA_UINT16_TO_BYTES(u16)          STA_UINT16_TO_BYTES_BE(u16)
#  define STA_UINT16_TO_BYTES_SWAP(u16)     STA_UINT16_TO_BYTES_LE(u16)

#  define STA_UINT32_TO_BE(u32)             (u32)
#  define STA_UINT32_TO_LE(u32)             STA_UINT32_SWAP_BYTE_ORDER(u32)
#  define STA_UINT32_TO_BYTES(u32)          STA_UINT32_TO_BYTES_BE(u32)
#  define STA_UINT32_TO_BYTES_SWAP(u32)     STA_UINT32_TO_BYTES_LE(u32)

#endif // STA_MCU_BIG_ENDIAN


#endif // STA_CORE_ENDIAN_HPP