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
_copy(uint8_t * to,unsigned int to_len,const uint8_t * from,unsigned int from_len)40 unsigned int _copy(uint8_t *to, unsigned int to_len,
41 const uint8_t *from, unsigned int from_len)
42 {
43 if (from_len <= to_len) {
44 (void)memcpy(to, from, from_len);
45 return from_len;
46 } else {
47 return TC_CRYPTO_FAIL;
48 }
49 }
50
_set(void * to,uint8_t val,unsigned int len)51 void _set(void *to, uint8_t val, unsigned int len)
52 {
53 (void)memset(to, val, len);
54 }
55
56 /*
57 * Doubles the value of a byte for values up to 127.
58 */
_double_byte(uint8_t a)59 uint8_t _double_byte(uint8_t a)
60 {
61 return ((a << 1) ^ ((a >> 7) * MASK_TWENTY_SEVEN));
62 }
63
_compare(const uint8_t * a,const uint8_t * b,size_t size)64 int _compare(const uint8_t *a, const uint8_t *b, size_t size)
65 {
66 const uint8_t *tempa = a;
67 const uint8_t *tempb = b;
68 uint8_t result = 0;
69
70 for (unsigned int i = 0; i < size; i++) {
71 result |= tempa[i] ^ tempb[i];
72 }
73 return result;
74 }
75
