71 lines
1.8 KiB
C
71 lines
1.8 KiB
C
/* some multiprecision utilities
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* Copyright (C) 1998-2001 D. Hugh Redelmeier.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* RCSID $Id: mp_defs.c,v 1.1 2006/01/05 12:37:11 as Exp $
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*/
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#include <freeswan.h>
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#include "constants.h"
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#include "defs.h"
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#include "mp_defs.h"
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#include "log.h"
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/* Convert MP_INT to network form (binary octets, big-endian).
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* We do the malloc; caller must eventually do free.
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*/
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chunk_t
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mpz_to_n(const MP_INT *mp, size_t bytes)
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{
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chunk_t r;
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MP_INT temp1, temp2;
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int i;
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r.len = bytes;
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r.ptr = alloc_bytes(r.len, "host representation of large integer");
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mpz_init(&temp1);
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mpz_init(&temp2);
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mpz_set(&temp1, mp);
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for (i = r.len-1; i >= 0; i--)
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{
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r.ptr[i] = mpz_mdivmod_ui(&temp2, NULL, &temp1, 1 << BITS_PER_BYTE);
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mpz_set(&temp1, &temp2);
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}
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passert(mpz_sgn(&temp1) == 0); /* we must have done all the bits */
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mpz_clear(&temp1);
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mpz_clear(&temp2);
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return r;
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}
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/* Convert network form (binary bytes, big-endian) to MP_INT.
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* The *mp must not be previously mpz_inited.
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*/
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void
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n_to_mpz(MP_INT *mp, const u_char *nbytes, size_t nlen)
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{
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size_t i;
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mpz_init_set_ui(mp, 0);
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for (i = 0; i != nlen; i++)
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{
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mpz_mul_ui(mp, mp, 1 << BITS_PER_BYTE);
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mpz_add_ui(mp, mp, nbytes[i]);
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}
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}
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