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       1                 :             : /* utils.c - TinyCrypt platform-dependent run-time operations */
       2                 :             : 
       3                 :             : /*
       4                 :             :  *  Copyright (C) 2017 by Intel Corporation, All Rights Reserved.
       5                 :             :  *
       6                 :             :  *  Redistribution and use in source and binary forms, with or without
       7                 :             :  *  modification, are permitted provided that the following conditions are met:
       8                 :             :  *
       9                 :             :  *    - Redistributions of source code must retain the above copyright notice,
      10                 :             :  *     this list of conditions and the following disclaimer.
      11                 :             :  *
      12                 :             :  *    - Redistributions in binary form must reproduce the above copyright
      13                 :             :  *    notice, this list of conditions and the following disclaimer in the
      14                 :             :  *    documentation and/or other materials provided with the distribution.
      15                 :             :  *
      16                 :             :  *    - Neither the name of Intel Corporation nor the names of its contributors
      17                 :             :  *    may be used to endorse or promote products derived from this software
      18                 :             :  *    without specific prior written permission.
      19                 :             :  *
      20                 :             :  *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
      21                 :             :  *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
      22                 :             :  *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
      23                 :             :  *  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
      24                 :             :  *  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
      25                 :             :  *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
      26                 :             :  *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
      27                 :             :  *  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
      28                 :             :  *  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
      29                 :             :  *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
      30                 :             :  *  POSSIBILITY OF SUCH DAMAGE.
      31                 :             :  */
      32                 :             : 
      33                 :             : #include <tinycrypt/utils.h>
      34                 :             : #include <tinycrypt/constants.h>
      35                 :             : 
      36                 :             : #include <string.h>
      37                 :             : 
      38                 :             : #define MASK_TWENTY_SEVEN 0x1b
      39                 :             : 
      40                 :           0 : unsigned int _copy(uint8_t *to, unsigned int to_len,
      41                 :             :                    const uint8_t *from, unsigned int from_len)
      42                 :             : {
      43         [ #  # ]:           0 :         if (from_len <= to_len) {
      44                 :           0 :                 (void)memcpy(to, from, from_len);
      45                 :           0 :                 return from_len;
      46                 :             :         } else {
      47                 :             :                 return TC_CRYPTO_FAIL;
      48                 :             :         }
      49                 :             : }
      50                 :             : 
      51                 :           0 : void _set(void *to, uint8_t val, unsigned int len)
      52                 :             : {
      53                 :           0 :         (void)memset(to, val, len);
      54                 :           0 : }
      55                 :             : 
      56                 :             : /*
      57                 :             :  * Doubles the value of a byte for values up to 127.
      58                 :             :  */
      59                 :           0 : uint8_t _double_byte(uint8_t a)
      60                 :             : {
      61                 :           0 :         return ((a<<1) ^ ((a>>7) * MASK_TWENTY_SEVEN));
      62                 :             : }
      63                 :             : 
      64                 :           0 : int _compare(const uint8_t *a, const uint8_t *b, size_t size)
      65                 :             : {
      66                 :           0 :         const uint8_t *tempa = a;
      67                 :           0 :         const uint8_t *tempb = b;
      68                 :           0 :         uint8_t result = 0;
      69                 :             : 
      70         [ #  # ]:           0 :         for (unsigned int i = 0; i < size; i++) {
      71                 :           0 :                 result |= tempa[i] ^ tempb[i];
      72                 :             :         }
      73                 :           0 :         return result;
      74                 :             : }