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/*
* mplogic.c
*
* Bitwise logical operations on MPI values
*
* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is the MPI Arbitrary Precision Integer Arithmetic library.
*
* The Initial Developer of the Original Code is
* Michael J. Fromberger.
* Portions created by the Initial Developer are Copyright (C) 1998
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
/*
* Copyright 2007 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*
* Sun elects to use this software under the MPL license.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
/* $Id: mplogic.c,v 1.15 2004/04/27 23:04:36 gerv%gerv.net Exp $ */
#include "mpi-priv.h"
#include "mplogic.h"
/* {{{ Lookup table for population count */
static unsigned char bitc[] = {
0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8
};
/* }}} */
/*
mpl_rsh(a, b, d) - b = a >> d
mpl_lsh(a, b, d) - b = a << d
*/
/* {{{ mpl_rsh(a, b, d) */
mp_err mpl_rsh(const mp_int *a, mp_int *b, mp_digit d)
{
mp_err res;
ARGCHK(a != NULL && b != NULL, MP_BADARG);
if((res = mp_copy(a, b)) != MP_OKAY)
return res;
s_mp_div_2d(b, d);
return MP_OKAY;
} /* end mpl_rsh() */
/* }}} */
/* {{{ mpl_lsh(a, b, d) */
mp_err mpl_lsh(const mp_int *a, mp_int *b, mp_digit d)
{
mp_err res;
ARGCHK(a != NULL && b != NULL, MP_BADARG);
if((res = mp_copy(a, b)) != MP_OKAY)
return res;
return s_mp_mul_2d(b, d);
} /* end mpl_lsh() */
/* }}} */
/*------------------------------------------------------------------------*/
/*
mpl_set_bit
Returns MP_OKAY or some error code.
Grows a if needed to set a bit to 1.
*/
mp_err mpl_set_bit(mp_int *a, mp_size bitNum, mp_size value)
{
mp_size ix;
mp_err rv;
mp_digit mask;
ARGCHK(a != NULL, MP_BADARG);
ix = bitNum / MP_DIGIT_BIT;
if (ix + 1 > MP_USED(a)) {
rv = s_mp_pad(a, ix + 1);
if (rv != MP_OKAY)
return rv;
}
bitNum = bitNum % MP_DIGIT_BIT;
mask = (mp_digit)1 << bitNum;
if (value)
MP_DIGIT(a,ix) |= mask;
else
MP_DIGIT(a,ix) &= ~mask;
s_mp_clamp(a);
return MP_OKAY;
}
/*
mpl_get_bit
returns 0 or 1 or some (negative) error code.
*/
mp_err mpl_get_bit(const mp_int *a, mp_size bitNum)
{
mp_size bit, ix;
mp_err rv;
ARGCHK(a != NULL, MP_BADARG);
ix = bitNum / MP_DIGIT_BIT;
ARGCHK(ix <= MP_USED(a) - 1, MP_RANGE);
bit = bitNum % MP_DIGIT_BIT;
rv = (mp_err)(MP_DIGIT(a, ix) >> bit) & 1;
return rv;
}
/*
mpl_get_bits
- Extracts numBits bits from a, where the least significant extracted bit
is bit lsbNum. Returns a negative value if error occurs.
- Because sign bit is used to indicate error, maximum number of bits to
be returned is the lesser of (a) the number of bits in an mp_digit, or
(b) one less than the number of bits in an mp_err.
- lsbNum + numbits can be greater than the number of significant bits in
integer a, as long as bit lsbNum is in the high order digit of a.
*/
mp_err mpl_get_bits(const mp_int *a, mp_size lsbNum, mp_size numBits)
{
mp_size rshift = (lsbNum % MP_DIGIT_BIT);
mp_size lsWndx = (lsbNum / MP_DIGIT_BIT);
mp_digit * digit = MP_DIGITS(a) + lsWndx;
mp_digit mask = ((1 << numBits) - 1);
ARGCHK(numBits < CHAR_BIT * sizeof mask, MP_BADARG);
ARGCHK(MP_HOWMANY(lsbNum, MP_DIGIT_BIT) <= MP_USED(a), MP_RANGE);
if ((numBits + lsbNum % MP_DIGIT_BIT <= MP_DIGIT_BIT) ||
(lsWndx + 1 >= MP_USED(a))) {
mask &= (digit[0] >> rshift);
} else {
mask &= ((digit[0] >> rshift) | (digit[1] << (MP_DIGIT_BIT - rshift)));
}
return (mp_err)mask;
}
/*
mpl_significant_bits
returns number of significnant bits in abs(a).
returns 1 if value is zero.
*/
mp_err mpl_significant_bits(const mp_int *a)
{
mp_err bits = 0;
int ix;
ARGCHK(a != NULL, MP_BADARG);
ix = MP_USED(a);
for (ix = MP_USED(a); ix > 0; ) {
mp_digit d;
d = MP_DIGIT(a, --ix);
if (d) {
while (d) {
++bits;
d >>= 1;
}
break;
}
}
bits += ix * MP_DIGIT_BIT;
if (!bits)
bits = 1;
return bits;
}
/*------------------------------------------------------------------------*/
/* HERE THERE BE DRAGONS */
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