mirror of
https://github.com/cryb-to/cryb-to.git
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82 lines
2.4 KiB
C
82 lines
2.4 KiB
C
/*
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* Copyright (c) 2014-2016 Dag-Erling Smørgrav
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* 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
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. 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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* 3. The name of the author may not be used to endorse or promote
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* products derived from this software without specific prior written
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* permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* 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 AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include "cryb/impl.h"
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#include <stddef.h>
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#include <stdint.h>
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#include <cryb/endian.h>
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#include <cryb/mpi.h>
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#include "cryb_mpi_impl.h"
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/*
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* Load value from an array of bytes
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*/
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int
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mpi_load(cryb_mpi *X, const uint8_t *a, size_t len)
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{
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int i;
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mpi_zero(X);
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/* skip zeroes */
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while (len > 0 && *a == 0)
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--len, ++a;
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if (len == 0)
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return (0);
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/* make room */
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if (mpi_grow(X, len * 8) != 0)
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return (-1);
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/* load whole words */
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for (i = 0; len >= 4; ++i, len -= 4)
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X->words[i] = be32dec(&a[len - 4]);
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/* load remaining bytes */
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switch (len) {
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case 3:
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X->words[i] |= a[len - 3] << 16;
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case 2:
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X->words[i] |= a[len - 2] << 8;
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case 1:
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X->words[i] |= a[len - 1];
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break;
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case 0:
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--i;
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CRYB_NO_DEFAULT_CASE;
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}
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/* i now points to the msw */
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/* compute msb of msw */
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/* XXX use flsl() */
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for (X->msb = 31; X->msb > 0; --X->msb)
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if (X->words[i] & (1 << X->msb))
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break;
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/* add msw offset */
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X->msb += i * 32 + 1;
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return (0);
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}
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