66 lines
2.3 KiB
C
66 lines
2.3 KiB
C
/* utils.c - TinyCrypt platform-dependent run-time operations */
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/*
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* Copyright (C) 2015 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 <string.h>
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#define MASK_MOST_SIG_BIT 0x80
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#define MASK_TWENTY_SEVEN 0x1b
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uint32_t _copy(uint8_t *to, uint32_t to_len,
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const uint8_t *from, uint32_t 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_FAIL;
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}
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}
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void _set(uint8_t *to, uint8_t val, uint32_t 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. Original 'return
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* ((a<<1) ^ ((a>>7) * 0x1b))' re-written to avoid extra multiplicaiton which
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* the compiler won't be able to optimize
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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 & MASK_MOST_SIG_BIT) ?
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((a << 1) ^ MASK_TWENTY_SEVEN) : (a << 1);
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}
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