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/* $OpenBSD: bn_primitives.c,v 1.2 2023/06/21 07:48:41 jsing Exp $ */
/*
* Copyright (c) 2023 Joel Sing <jsing@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <openssl/bn.h>
#include "bn_arch.h"
#include "bn_internal.h"
#include "bn_local.h"
#ifndef HAVE_BN_CLZW
#ifndef HAVE_BN_WORD_CLZ
int
bn_word_clz(BN_ULONG w)
{
BN_ULONG bits, mask, shift;
bits = shift = BN_BITS2;
mask = 0;
while ((shift >>= 1) != 0) {
bits += (shift & mask) - (shift & ~mask);
mask = bn_ct_ne_zero_mask(w >> bits);
}
bits += 1 & mask;
bits -= bn_ct_eq_zero(w);
return BN_BITS2 - bits;
}
#endif
#endif
#ifndef HAVE_BN_BITSIZE
int
bn_bitsize(const BIGNUM *bn)
{
BN_ULONG n = 0, x = 0;
BN_ULONG mask, w;
int i = 0;
while (i < bn->top) {
w = bn->d[i];
mask = bn_ct_ne_zero_mask(w);
n = ((BN_ULONG)i & mask) | (n & ~mask);
x = (w & mask) | (x & ~mask);
i++;
}
return (n + 1) * BN_BITS2 - bn_clzw(x);
}
#endif
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