library/alignment.h

/**
 * \file alignment.h
 *
 * \brief Utility code for dealing with unaligned memory accesses
 */
/*
 *  Copyright The Mbed TLS Contributors
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  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.
 */

#ifndef MBEDTLS_LIBRARY_ALIGNMENT_H
#define MBEDTLS_LIBRARY_ALIGNMENT_H

#include <stdint.h>
#include <string.h>
#include <stdlib.h>

#include "mbedtls/build_info.h"

/**
 * Read the unsigned 16 bits integer from the given address, which need not
 * be aligned.
 *
 * \param   p pointer to 2 bytes of data
 * \return  Data at the given address
 */
inline uint16_t mbedtls_get_unaligned_uint16( const void *p )
{
    uint16_t r;
    memcpy( &r, p, sizeof( r ) );
    return r;
}

/**
 * Write the unsigned 16 bits integer to the given address, which need not
 * be aligned.
 *
 * \param   p pointer to 2 bytes of data
 * \param   x data to write
 */
inline void mbedtls_put_unaligned_uint16( void *p, uint16_t x )
{
    memcpy( p, &x, sizeof( x ) );
}

/**
 * Read the unsigned 32 bits integer from the given address, which need not
 * be aligned.
 *
 * \param   p pointer to 4 bytes of data
 * \return  Data at the given address
 */
inline uint32_t mbedtls_get_unaligned_uint32( const void *p )
{
    uint32_t r;
    memcpy( &r, p, sizeof( r ) );
    return r;
}

/**
 * Write the unsigned 32 bits integer to the given address, which need not
 * be aligned.
 *
 * \param   p pointer to 4 bytes of data
 * \param   x data to write
 */
inline void mbedtls_put_unaligned_uint32( void *p, uint32_t x )
{
    memcpy( p, &x, sizeof( x ) );
}

/**
 * Read the unsigned 64 bits integer from the given address, which need not
 * be aligned.
 *
 * \param   p pointer to 8 bytes of data
 * \return  Data at the given address
 */
inline uint64_t mbedtls_get_unaligned_uint64( const void *p )
{
    uint64_t r;
    memcpy( &r, p, sizeof( r ) );
    return r;
}

/**
 * Write the unsigned 64 bits integer to the given address, which need not
 * be aligned.
 *
 * \param   p pointer to 8 bytes of data
 * \param   x data to write
 */
inline void mbedtls_put_unaligned_uint64( void *p, uint64_t x )
{
    memcpy( p, &x, sizeof( x ) );
}

/** Byte Reading Macros
 *
 * Given a multi-byte integer \p x, MBEDTLS_BYTE_n retrieves the n-th
 * byte from x, where byte 0 is the least significant byte.
 */
#define MBEDTLS_BYTE_0( x ) ( (uint8_t) (   ( x )         & 0xff ) )
#define MBEDTLS_BYTE_1( x ) ( (uint8_t) ( ( ( x ) >> 8  ) & 0xff ) )
#define MBEDTLS_BYTE_2( x ) ( (uint8_t) ( ( ( x ) >> 16 ) & 0xff ) )
#define MBEDTLS_BYTE_3( x ) ( (uint8_t) ( ( ( x ) >> 24 ) & 0xff ) )
#define MBEDTLS_BYTE_4( x ) ( (uint8_t) ( ( ( x ) >> 32 ) & 0xff ) )
#define MBEDTLS_BYTE_5( x ) ( (uint8_t) ( ( ( x ) >> 40 ) & 0xff ) )
#define MBEDTLS_BYTE_6( x ) ( (uint8_t) ( ( ( x ) >> 48 ) & 0xff ) )
#define MBEDTLS_BYTE_7( x ) ( (uint8_t) ( ( ( x ) >> 56 ) & 0xff ) )

/*
 * Detect GCC built-in byteswap routines
 */
#if defined(__GNUC__) && defined(__GNUC_PREREQ)
#if __GNUC_PREREQ(4,8)
#define MBEDTLS_BSWAP16 __builtin_bswap16
#endif /* __GNUC_PREREQ(4,8) */
#if __GNUC_PREREQ(4,3)
#define MBEDTLS_BSWAP32 __builtin_bswap32
#define MBEDTLS_BSWAP64 __builtin_bswap64
#endif /* __GNUC_PREREQ(4,3) */
#endif /* defined(__GNUC__) && defined(__GNUC_PREREQ) */

/*
 * Detect Clang built-in byteswap routines
 */
#if defined(__clang__) && defined(__has_builtin)
#if __has_builtin(__builtin_bswap16)
#define MBEDTLS_BSWAP16 __builtin_bswap16
#endif /* __has_builtin(__builtin_bswap16) */
#if __has_builtin(__builtin_bswap32)
#define MBEDTLS_BSWAP32 __builtin_bswap32
#endif /* __has_builtin(__builtin_bswap32) */
#if __has_builtin(__builtin_bswap64)
#define MBEDTLS_BSWAP64 __builtin_bswap64
#endif /* __has_builtin(__builtin_bswap64) */
#endif /* defined(__clang__) && defined(__has_builtin) */

/*
 * Detect MSVC built-in byteswap routines
 */
#if defined(_MSC_VER)
#define MBEDTLS_BSWAP16 _byteswap_ushort
#define MBEDTLS_BSWAP32 _byteswap_ulong
#define MBEDTLS_BSWAP64 _byteswap_uint64
#endif /* defined(_MSC_VER) */

/*
 * Where compiler built-ins are not present, fall back to C code that the
 * compiler may be able to detect and transform into the relevant bswap or
 * similar instruction.
 */
#if !defined(MBEDTLS_BSWAP16)
static inline uint16_t mbedtls_bswap16( uint16_t x ) {
    return
         ( x & 0x00ff ) << 8 |
         ( x & 0xff00 ) >> 8;
}
#define MBEDTLS_BSWAP16 mbedtls_bswap16
#endif /* !defined(MBEDTLS_BSWAP16) */

#if !defined(MBEDTLS_BSWAP32)
static inline uint32_t mbedtls_bswap32( uint32_t x ) {
    return
         ( x & 0x000000ff ) << 24 |
         ( x & 0x0000ff00 ) <<  8 |
         ( x & 0x00ff0000 ) >>  8 |
         ( x & 0xff000000 ) >> 24;
}
#define MBEDTLS_BSWAP32 mbedtls_bswap32
#endif /* !defined(MBEDTLS_BSWAP32) */

#if !defined(MBEDTLS_BSWAP64)
static inline uint64_t mbedtls_bswap64( uint64_t x ) {
    return
         ( x & 0x00000000000000ff ) << 56 |
         ( x & 0x000000000000ff00 ) << 40 |
         ( x & 0x0000000000ff0000 ) << 24 |
         ( x & 0x00000000ff000000 ) <<  8 |
         ( x & 0x000000ff00000000 ) >>  8 |
         ( x & 0x0000ff0000000000 ) >> 24 |
         ( x & 0x00ff000000000000 ) >> 40 |
         ( x & 0xff00000000000000 ) >> 56;
}
#define MBEDTLS_BSWAP64 mbedtls_bswap64
#endif /* !defined(MBEDTLS_BSWAP64) */

#if !defined(__BYTE_ORDER__)
static const uint16_t mbedtls_byte_order_detector = { 0x100 };
#define MBEDTLS_IS_BIG_ENDIAN (*((unsigned char *) (&mbedtls_byte_order_detector)) == 0x01)
#else
#define MBEDTLS_IS_BIG_ENDIAN ((__BYTE_ORDER__) == (__ORDER_BIG_ENDIAN__))
#endif /* !defined(__BYTE_ORDER__) */

/**
 * Get the unsigned 32 bits integer corresponding to four bytes in
 * big-endian order (MSB first).
 *
 * \param   data    Base address of the memory to get the four bytes from.
 * \param   offset  Offset from \p data of the first and most significant
 *                  byte of the four bytes to build the 32 bits unsigned
 *                  integer from.
 */
#define MBEDTLS_GET_UINT32_BE( data, offset )                              \
    ( ( MBEDTLS_IS_BIG_ENDIAN )                                            \
        ? mbedtls_get_unaligned_uint32((data) + (offset))                  \
        : MBEDTLS_BSWAP32(mbedtls_get_unaligned_uint32((data) + (offset))) \
    )

/**
 * Put in memory a 32 bits unsigned integer in big-endian order.
 *
 * \param   n       32 bits unsigned integer to put in memory.
 * \param   data    Base address of the memory where to put the 32
 *                  bits unsigned integer in.
 * \param   offset  Offset from \p data where to put the most significant
 *                  byte of the 32 bits unsigned integer \p n.
 */
#define MBEDTLS_PUT_UINT32_BE( n, data, offset )                             \
{                                                                            \
    if ( MBEDTLS_IS_BIG_ENDIAN )                                             \
    {                                                                        \
        mbedtls_put_unaligned_uint32((data) + (offset), (uint32_t)(n));      \
    }                                                                        \
    else                                                                     \
    {                                                                        \
        mbedtls_put_unaligned_uint32((data) + (offset), MBEDTLS_BSWAP32((uint32_t)(n))); \
    }                                                                        \
}

/**
 * Get the unsigned 32 bits integer corresponding to four bytes in
 * little-endian order (LSB first).
 *
 * \param   data    Base address of the memory to get the four bytes from.
 * \param   offset  Offset from \p data of the first and least significant
 *                  byte of the four bytes to build the 32 bits unsigned
 *                  integer from.
 */
#define MBEDTLS_GET_UINT32_LE( data, offset )                              \
    ( ( MBEDTLS_IS_BIG_ENDIAN )                                            \
        ? MBEDTLS_BSWAP32(mbedtls_get_unaligned_uint32((data) + (offset))) \
        : mbedtls_get_unaligned_uint32((data) + (offset))                  \
    )


/**
 * Put in memory a 32 bits unsigned integer in little-endian order.
 *
 * \param   n       32 bits unsigned integer to put in memory.
 * \param   data    Base address of the memory where to put the 32
 *                  bits unsigned integer in.
 * \param   offset  Offset from \p data where to put the least significant
 *                  byte of the 32 bits unsigned integer \p n.
 */
#define MBEDTLS_PUT_UINT32_LE( n, data, offset )                             \
{                                                                            \
    if ( MBEDTLS_IS_BIG_ENDIAN )                                             \
    {                                                                        \
        mbedtls_put_unaligned_uint32((data) + (offset), MBEDTLS_BSWAP32((uint32_t)(n))); \
    }                                                                        \
    else                                                                     \
    {                                                                        \
        mbedtls_put_unaligned_uint32((data) + (offset), ((uint32_t)(n)));      \
    }                                                                        \
}

/**
 * Get the unsigned 16 bits integer corresponding to two bytes in
 * little-endian order (LSB first).
 *
 * \param   data    Base address of the memory to get the two bytes from.
 * \param   offset  Offset from \p data of the first and least significant
 *                  byte of the two bytes to build the 16 bits unsigned
 *                  integer from.
 */
#define MBEDTLS_GET_UINT16_LE( data, offset )                              \
    ( ( MBEDTLS_IS_BIG_ENDIAN )                                            \
        ? MBEDTLS_BSWAP16(mbedtls_get_unaligned_uint16((data) + (offset))) \
        : mbedtls_get_unaligned_uint16((data) + (offset))                  \
    )

/**
 * Put in memory a 16 bits unsigned integer in little-endian order.
 *
 * \param   n       16 bits unsigned integer to put in memory.
 * \param   data    Base address of the memory where to put the 16
 *                  bits unsigned integer in.
 * \param   offset  Offset from \p data where to put the least significant
 *                  byte of the 16 bits unsigned integer \p n.
 */
#define MBEDTLS_PUT_UINT16_LE( n, data, offset )                             \
{                                                                            \
    if ( MBEDTLS_IS_BIG_ENDIAN )                                             \
    {                                                                        \
        mbedtls_put_unaligned_uint16((data) + (offset), MBEDTLS_BSWAP16((uint16_t)(n))); \
    }                                                                        \
    else                                                                     \
    {                                                                        \
        mbedtls_put_unaligned_uint16((data) + (offset), (uint16_t)(n));      \
    }                                                                        \
}

/**
 * Get the unsigned 16 bits integer corresponding to two bytes in
 * big-endian order (MSB first).
 *
 * \param   data    Base address of the memory to get the two bytes from.
 * \param   offset  Offset from \p data of the first and most significant
 *                  byte of the two bytes to build the 16 bits unsigned
 *                  integer from.
 */
#define MBEDTLS_GET_UINT16_BE( data, offset )                              \
    ( ( MBEDTLS_IS_BIG_ENDIAN )                                            \
        ? mbedtls_get_unaligned_uint16((data) + (offset))                  \
        : MBEDTLS_BSWAP16(mbedtls_get_unaligned_uint16((data) + (offset))) \
    )

/**
 * Put in memory a 16 bits unsigned integer in big-endian order.
 *
 * \param   n       16 bits unsigned integer to put in memory.
 * \param   data    Base address of the memory where to put the 16
 *                  bits unsigned integer in.
 * \param   offset  Offset from \p data where to put the most significant
 *                  byte of the 16 bits unsigned integer \p n.
 */
#define MBEDTLS_PUT_UINT16_BE( n, data, offset )                             \
{                                                                            \
    if ( MBEDTLS_IS_BIG_ENDIAN )                                             \
    {                                                                        \
        mbedtls_put_unaligned_uint16((data) + (offset), (uint16_t)(n));      \
    }                                                                        \
    else                                                                     \
    {                                                                        \
        mbedtls_put_unaligned_uint16((data) + (offset), MBEDTLS_BSWAP16((uint16_t)(n))); \
    }                                                                        \
}

/**
 * Get the unsigned 24 bits integer corresponding to three bytes in
 * big-endian order (MSB first).
 *
 * \param   data    Base address of the memory to get the three bytes from.
 * \param   offset  Offset from \p data of the first and most significant
 *                  byte of the three bytes to build the 24 bits unsigned
 *                  integer from.
 */
#define MBEDTLS_GET_UINT24_BE( data , offset )                  \
    (                                                           \
          ( (uint32_t) ( data )[( offset )    ] << 16 )         \
        | ( (uint32_t) ( data )[( offset ) + 1] << 8  )         \
        | ( (uint32_t) ( data )[( offset ) + 2]       )         \
    )

/**
 * Put in memory a 24 bits unsigned integer in big-endian order.
 *
 * \param   n       24 bits unsigned integer to put in memory.
 * \param   data    Base address of the memory where to put the 24
 *                  bits unsigned integer in.
 * \param   offset  Offset from \p data where to put the most significant
 *                  byte of the 24 bits unsigned integer \p n.
 */
#define MBEDTLS_PUT_UINT24_BE( n, data, offset )                \
{                                                               \
    ( data )[( offset )    ] = MBEDTLS_BYTE_2( n );             \
    ( data )[( offset ) + 1] = MBEDTLS_BYTE_1( n );             \
    ( data )[( offset ) + 2] = MBEDTLS_BYTE_0( n );             \
}

/**
 * Get the unsigned 24 bits integer corresponding to three bytes in
 * little-endian order (LSB first).
 *
 * \param   data    Base address of the memory to get the three bytes from.
 * \param   offset  Offset from \p data of the first and least significant
 *                  byte of the three bytes to build the 24 bits unsigned
 *                  integer from.
 */
#define MBEDTLS_GET_UINT24_LE( data, offset )                   \
    (                                                           \
          ( (uint32_t) ( data )[( offset )    ]       )         \
        | ( (uint32_t) ( data )[( offset ) + 1] <<  8 )         \
        | ( (uint32_t) ( data )[( offset ) + 2] << 16 )         \
    )

/**
 * Put in memory a 24 bits unsigned integer in little-endian order.
 *
 * \param   n       24 bits unsigned integer to put in memory.
 * \param   data    Base address of the memory where to put the 24
 *                  bits unsigned integer in.
 * \param   offset  Offset from \p data where to put the least significant
 *                  byte of the 24 bits unsigned integer \p n.
 */
#define MBEDTLS_PUT_UINT24_LE( n, data, offset )                \
{                                                               \
    ( data )[( offset )    ] = MBEDTLS_BYTE_0( n );             \
    ( data )[( offset ) + 1] = MBEDTLS_BYTE_1( n );             \
    ( data )[( offset ) + 2] = MBEDTLS_BYTE_2( n );             \
}

/**
 * Get the unsigned 64 bits integer corresponding to eight bytes in
 * big-endian order (MSB first).
 *
 * \param   data    Base address of the memory to get the eight bytes from.
 * \param   offset  Offset from \p data of the first and most significant
 *                  byte of the eight bytes to build the 64 bits unsigned
 *                  integer from.
 */
#define MBEDTLS_GET_UINT64_BE( data, offset )                              \
    ( ( MBEDTLS_IS_BIG_ENDIAN )                                            \
        ? mbedtls_get_unaligned_uint64((data) + (offset))                  \
        : MBEDTLS_BSWAP64(mbedtls_get_unaligned_uint64((data) + (offset))) \
    )

/**
 * Put in memory a 64 bits unsigned integer in big-endian order.
 *
 * \param   n       64 bits unsigned integer to put in memory.
 * \param   data    Base address of the memory where to put the 64
 *                  bits unsigned integer in.
 * \param   offset  Offset from \p data where to put the most significant
 *                  byte of the 64 bits unsigned integer \p n.
 */
#define MBEDTLS_PUT_UINT64_BE( n, data, offset )                             \
{                                                                            \
    if ( MBEDTLS_IS_BIG_ENDIAN )                                             \
    {                                                                        \
        mbedtls_put_unaligned_uint64((data) + (offset), (uint64_t)(n));      \
    }                                                                        \
    else                                                                     \
    {                                                                        \
        mbedtls_put_unaligned_uint64((data) + (offset), MBEDTLS_BSWAP64((uint64_t)(n))); \
    }                                                                        \
}

/**
 * Get the unsigned 64 bits integer corresponding to eight bytes in
 * little-endian order (LSB first).
 *
 * \param   data    Base address of the memory to get the eight bytes from.
 * \param   offset  Offset from \p data of the first and least significant
 *                  byte of the eight bytes to build the 64 bits unsigned
 *                  integer from.
 */
#define MBEDTLS_GET_UINT64_LE( data, offset )                              \
    ( ( MBEDTLS_IS_BIG_ENDIAN )                                            \
        ? MBEDTLS_BSWAP64(mbedtls_get_unaligned_uint64((data) + (offset))) \
        : mbedtls_get_unaligned_uint64((data) + (offset))                  \
    )

/**
 * Put in memory a 64 bits unsigned integer in little-endian order.
 *
 * \param   n       64 bits unsigned integer to put in memory.
 * \param   data    Base address of the memory where to put the 64
 *                  bits unsigned integer in.
 * \param   offset  Offset from \p data where to put the least significant
 *                  byte of the 64 bits unsigned integer \p n.
 */
#define MBEDTLS_PUT_UINT64_LE( n, data, offset )                             \
{                                                                            \
    if ( MBEDTLS_IS_BIG_ENDIAN )                                             \
    {                                                                        \
        mbedtls_put_unaligned_uint64((data) + (offset), MBEDTLS_BSWAP64((uint64_t)(n))); \
    }                                                                        \
    else                                                                     \
    {                                                                        \
        mbedtls_put_unaligned_uint64((data) + (offset), (uint64_t)(n));      \
    }                                                                        \
}

#endif /* MBEDTLS_LIBRARY_ALIGNMENT_H */