42 lines
1.1 KiB
C
42 lines
1.1 KiB
C
/*
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* Copyright (c) 2024 Lucas Gabriel Vuotto <lucas@lgv5.net>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include "lilcrypto.h"
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uint32_t
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lc_ct_cmp(const uint8_t *x, const uint8_t *y, size_t l)
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{
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uint32_t r = 0;
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for (; l > 0; l--)
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r |= *x++ ^ *y++;
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return lc_ct_mask32(r);
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}
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uint32_t
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lc_ct_mask32(uint32_t x)
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{
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/* Ensures that if any bit is set, then LSB is set. */
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x |= x >> 16;
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x |= x >> 8;
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x |= x >> 4;
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x |= x >> 2;
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x |= x >> 1;
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return UINT32_MAX + (x & 1);
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}
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