/* utils.c - TinyCrypt platform-dependent run-time operations */
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/*
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* Copyright (C) 2017 by Intel Corporation, All Rights Reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* - Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* - Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* - Neither the name of Intel Corporation nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <tinycrypt/utils.h>
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#include <tinycrypt/constants.h>
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#include <string.h>
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#define MASK_TWENTY_SEVEN 0x1b
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unsigned int _copy(uint8_t *to, unsigned int to_len,
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const uint8_t *from, unsigned int from_len)
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{
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if (from_len <= to_len) {
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(void)memcpy(to, from, from_len);
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return from_len;
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} else {
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return TC_CRYPTO_FAIL;
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}
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}
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void _set(void *to, uint8_t val, unsigned int len)
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{
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(void)memset(to, val, len);
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}
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/*
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* Doubles the value of a byte for values up to 127.
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*/
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uint8_t _double_byte(uint8_t a)
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{
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return ((a<<1) ^ ((a>>7) * MASK_TWENTY_SEVEN));
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}
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int _compare(const uint8_t *a, const uint8_t *b, size_t size)
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{
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const uint8_t *tempa = a;
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const uint8_t *tempb = b;
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uint8_t result = 0;
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for (unsigned int i = 0; i < size; i++) {
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result |= tempa[i] ^ tempb[i];
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}
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return result;
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}
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