mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-10-29 23:53:32 +00:00
8d8472cfde
Fix typo/spello of "functions". Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Link: https://lkml.kernel.org/r/8df15173-a6df-9426-7cad-a2d279bf1170@infradead.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
307 lines
6.7 KiB
C
307 lines
6.7 KiB
C
/* mpi-bit.c - MPI bit level functions
|
|
* Copyright (C) 1998, 1999 Free Software Foundation, Inc.
|
|
*
|
|
* This file is part of GnuPG.
|
|
*
|
|
* GnuPG is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* GnuPG is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
|
|
*/
|
|
|
|
#include "mpi-internal.h"
|
|
#include "longlong.h"
|
|
|
|
#define A_LIMB_1 ((mpi_limb_t) 1)
|
|
|
|
/****************
|
|
* Sometimes we have MSL (most significant limbs) which are 0;
|
|
* this is for some reasons not good, so this function removes them.
|
|
*/
|
|
void mpi_normalize(MPI a)
|
|
{
|
|
for (; a->nlimbs && !a->d[a->nlimbs - 1]; a->nlimbs--)
|
|
;
|
|
}
|
|
EXPORT_SYMBOL_GPL(mpi_normalize);
|
|
|
|
/****************
|
|
* Return the number of bits in A.
|
|
*/
|
|
unsigned mpi_get_nbits(MPI a)
|
|
{
|
|
unsigned n;
|
|
|
|
mpi_normalize(a);
|
|
|
|
if (a->nlimbs) {
|
|
mpi_limb_t alimb = a->d[a->nlimbs - 1];
|
|
if (alimb)
|
|
n = count_leading_zeros(alimb);
|
|
else
|
|
n = BITS_PER_MPI_LIMB;
|
|
n = BITS_PER_MPI_LIMB - n + (a->nlimbs - 1) * BITS_PER_MPI_LIMB;
|
|
} else
|
|
n = 0;
|
|
return n;
|
|
}
|
|
EXPORT_SYMBOL_GPL(mpi_get_nbits);
|
|
|
|
/****************
|
|
* Test whether bit N is set.
|
|
*/
|
|
int mpi_test_bit(MPI a, unsigned int n)
|
|
{
|
|
unsigned int limbno, bitno;
|
|
mpi_limb_t limb;
|
|
|
|
limbno = n / BITS_PER_MPI_LIMB;
|
|
bitno = n % BITS_PER_MPI_LIMB;
|
|
|
|
if (limbno >= a->nlimbs)
|
|
return 0; /* too far left: this is a 0 */
|
|
limb = a->d[limbno];
|
|
return (limb & (A_LIMB_1 << bitno)) ? 1 : 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(mpi_test_bit);
|
|
|
|
/****************
|
|
* Set bit N of A.
|
|
*/
|
|
void mpi_set_bit(MPI a, unsigned int n)
|
|
{
|
|
unsigned int i, limbno, bitno;
|
|
|
|
limbno = n / BITS_PER_MPI_LIMB;
|
|
bitno = n % BITS_PER_MPI_LIMB;
|
|
|
|
if (limbno >= a->nlimbs) {
|
|
for (i = a->nlimbs; i < a->alloced; i++)
|
|
a->d[i] = 0;
|
|
mpi_resize(a, limbno+1);
|
|
a->nlimbs = limbno+1;
|
|
}
|
|
a->d[limbno] |= (A_LIMB_1<<bitno);
|
|
}
|
|
|
|
/****************
|
|
* Set bit N of A. and clear all bits above
|
|
*/
|
|
void mpi_set_highbit(MPI a, unsigned int n)
|
|
{
|
|
unsigned int i, limbno, bitno;
|
|
|
|
limbno = n / BITS_PER_MPI_LIMB;
|
|
bitno = n % BITS_PER_MPI_LIMB;
|
|
|
|
if (limbno >= a->nlimbs) {
|
|
for (i = a->nlimbs; i < a->alloced; i++)
|
|
a->d[i] = 0;
|
|
mpi_resize(a, limbno+1);
|
|
a->nlimbs = limbno+1;
|
|
}
|
|
a->d[limbno] |= (A_LIMB_1<<bitno);
|
|
for (bitno++; bitno < BITS_PER_MPI_LIMB; bitno++)
|
|
a->d[limbno] &= ~(A_LIMB_1 << bitno);
|
|
a->nlimbs = limbno+1;
|
|
}
|
|
EXPORT_SYMBOL_GPL(mpi_set_highbit);
|
|
|
|
/****************
|
|
* clear bit N of A and all bits above
|
|
*/
|
|
void mpi_clear_highbit(MPI a, unsigned int n)
|
|
{
|
|
unsigned int limbno, bitno;
|
|
|
|
limbno = n / BITS_PER_MPI_LIMB;
|
|
bitno = n % BITS_PER_MPI_LIMB;
|
|
|
|
if (limbno >= a->nlimbs)
|
|
return; /* not allocated, therefore no need to clear bits :-) */
|
|
|
|
for ( ; bitno < BITS_PER_MPI_LIMB; bitno++)
|
|
a->d[limbno] &= ~(A_LIMB_1 << bitno);
|
|
a->nlimbs = limbno+1;
|
|
}
|
|
|
|
/****************
|
|
* Clear bit N of A.
|
|
*/
|
|
void mpi_clear_bit(MPI a, unsigned int n)
|
|
{
|
|
unsigned int limbno, bitno;
|
|
|
|
limbno = n / BITS_PER_MPI_LIMB;
|
|
bitno = n % BITS_PER_MPI_LIMB;
|
|
|
|
if (limbno >= a->nlimbs)
|
|
return; /* Don't need to clear this bit, it's far too left. */
|
|
a->d[limbno] &= ~(A_LIMB_1 << bitno);
|
|
}
|
|
EXPORT_SYMBOL_GPL(mpi_clear_bit);
|
|
|
|
|
|
/****************
|
|
* Shift A by COUNT limbs to the right
|
|
* This is used only within the MPI library
|
|
*/
|
|
void mpi_rshift_limbs(MPI a, unsigned int count)
|
|
{
|
|
mpi_ptr_t ap = a->d;
|
|
mpi_size_t n = a->nlimbs;
|
|
unsigned int i;
|
|
|
|
if (count >= n) {
|
|
a->nlimbs = 0;
|
|
return;
|
|
}
|
|
|
|
for (i = 0; i < n - count; i++)
|
|
ap[i] = ap[i+count];
|
|
ap[i] = 0;
|
|
a->nlimbs -= count;
|
|
}
|
|
|
|
/*
|
|
* Shift A by N bits to the right.
|
|
*/
|
|
void mpi_rshift(MPI x, MPI a, unsigned int n)
|
|
{
|
|
mpi_size_t xsize;
|
|
unsigned int i;
|
|
unsigned int nlimbs = (n/BITS_PER_MPI_LIMB);
|
|
unsigned int nbits = (n%BITS_PER_MPI_LIMB);
|
|
|
|
if (x == a) {
|
|
/* In-place operation. */
|
|
if (nlimbs >= x->nlimbs) {
|
|
x->nlimbs = 0;
|
|
return;
|
|
}
|
|
|
|
if (nlimbs) {
|
|
for (i = 0; i < x->nlimbs - nlimbs; i++)
|
|
x->d[i] = x->d[i+nlimbs];
|
|
x->d[i] = 0;
|
|
x->nlimbs -= nlimbs;
|
|
}
|
|
if (x->nlimbs && nbits)
|
|
mpihelp_rshift(x->d, x->d, x->nlimbs, nbits);
|
|
} else if (nlimbs) {
|
|
/* Copy and shift by more or equal bits than in a limb. */
|
|
xsize = a->nlimbs;
|
|
x->sign = a->sign;
|
|
RESIZE_IF_NEEDED(x, xsize);
|
|
x->nlimbs = xsize;
|
|
for (i = 0; i < a->nlimbs; i++)
|
|
x->d[i] = a->d[i];
|
|
x->nlimbs = i;
|
|
|
|
if (nlimbs >= x->nlimbs) {
|
|
x->nlimbs = 0;
|
|
return;
|
|
}
|
|
|
|
if (nlimbs) {
|
|
for (i = 0; i < x->nlimbs - nlimbs; i++)
|
|
x->d[i] = x->d[i+nlimbs];
|
|
x->d[i] = 0;
|
|
x->nlimbs -= nlimbs;
|
|
}
|
|
|
|
if (x->nlimbs && nbits)
|
|
mpihelp_rshift(x->d, x->d, x->nlimbs, nbits);
|
|
} else {
|
|
/* Copy and shift by less than bits in a limb. */
|
|
xsize = a->nlimbs;
|
|
x->sign = a->sign;
|
|
RESIZE_IF_NEEDED(x, xsize);
|
|
x->nlimbs = xsize;
|
|
|
|
if (xsize) {
|
|
if (nbits)
|
|
mpihelp_rshift(x->d, a->d, x->nlimbs, nbits);
|
|
else {
|
|
/* The rshift helper function is not specified for
|
|
* NBITS==0, thus we do a plain copy here.
|
|
*/
|
|
for (i = 0; i < x->nlimbs; i++)
|
|
x->d[i] = a->d[i];
|
|
}
|
|
}
|
|
}
|
|
MPN_NORMALIZE(x->d, x->nlimbs);
|
|
}
|
|
|
|
/****************
|
|
* Shift A by COUNT limbs to the left
|
|
* This is used only within the MPI library
|
|
*/
|
|
void mpi_lshift_limbs(MPI a, unsigned int count)
|
|
{
|
|
mpi_ptr_t ap;
|
|
int n = a->nlimbs;
|
|
int i;
|
|
|
|
if (!count || !n)
|
|
return;
|
|
|
|
RESIZE_IF_NEEDED(a, n+count);
|
|
|
|
ap = a->d;
|
|
for (i = n-1; i >= 0; i--)
|
|
ap[i+count] = ap[i];
|
|
for (i = 0; i < count; i++)
|
|
ap[i] = 0;
|
|
a->nlimbs += count;
|
|
}
|
|
|
|
/*
|
|
* Shift A by N bits to the left.
|
|
*/
|
|
void mpi_lshift(MPI x, MPI a, unsigned int n)
|
|
{
|
|
unsigned int nlimbs = (n/BITS_PER_MPI_LIMB);
|
|
unsigned int nbits = (n%BITS_PER_MPI_LIMB);
|
|
|
|
if (x == a && !n)
|
|
return; /* In-place shift with an amount of zero. */
|
|
|
|
if (x != a) {
|
|
/* Copy A to X. */
|
|
unsigned int alimbs = a->nlimbs;
|
|
int asign = a->sign;
|
|
mpi_ptr_t xp, ap;
|
|
|
|
RESIZE_IF_NEEDED(x, alimbs+nlimbs+1);
|
|
xp = x->d;
|
|
ap = a->d;
|
|
MPN_COPY(xp, ap, alimbs);
|
|
x->nlimbs = alimbs;
|
|
x->flags = a->flags;
|
|
x->sign = asign;
|
|
}
|
|
|
|
if (nlimbs && !nbits) {
|
|
/* Shift a full number of limbs. */
|
|
mpi_lshift_limbs(x, nlimbs);
|
|
} else if (n) {
|
|
/* We use a very dump approach: Shift left by the number of
|
|
* limbs plus one and than fix it up by an rshift.
|
|
*/
|
|
mpi_lshift_limbs(x, nlimbs+1);
|
|
mpi_rshift(x, x, BITS_PER_MPI_LIMB - nbits);
|
|
}
|
|
|
|
MPN_NORMALIZE(x->d, x->nlimbs);
|
|
}
|