331 lines
6.6 KiB
C
331 lines
6.6 KiB
C
/* mpiutil.ac - Utility functions for MPI
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* Copyright (C) 1998, 1999 Free Software Foundation, Inc.
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*
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* This file is part of GnuPG.
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*
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* GnuPG is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* GnuPG is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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*/
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#include "mpi-internal.h"
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/* Constants allocated right away at startup. */
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static MPI constants[MPI_NUMBER_OF_CONSTANTS];
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/* Initialize the MPI subsystem. This is called early and allows to
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* do some initialization without taking care of threading issues.
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*/
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static int __init mpi_init(void)
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{
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int idx;
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unsigned long value;
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for (idx = 0; idx < MPI_NUMBER_OF_CONSTANTS; idx++) {
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switch (idx) {
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case MPI_C_ZERO:
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value = 0;
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break;
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case MPI_C_ONE:
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value = 1;
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break;
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case MPI_C_TWO:
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value = 2;
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break;
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case MPI_C_THREE:
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value = 3;
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break;
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case MPI_C_FOUR:
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value = 4;
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break;
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case MPI_C_EIGHT:
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value = 8;
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break;
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default:
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pr_err("MPI: invalid mpi_const selector %d\n", idx);
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return -EFAULT;
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}
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constants[idx] = mpi_alloc_set_ui(value);
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constants[idx]->flags = (16|32);
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}
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return 0;
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}
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postcore_initcall(mpi_init);
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/* Return a constant MPI descripbed by NO which is one of the
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* MPI_C_xxx macros. There is no need to copy this returned value; it
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* may be used directly.
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*/
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MPI mpi_const(enum gcry_mpi_constants no)
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{
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if ((int)no < 0 || no > MPI_NUMBER_OF_CONSTANTS)
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pr_err("MPI: invalid mpi_const selector %d\n", no);
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if (!constants[no])
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pr_err("MPI: MPI subsystem not initialized\n");
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return constants[no];
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}
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EXPORT_SYMBOL_GPL(mpi_const);
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/****************
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* Note: It was a bad idea to use the number of limbs to allocate
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* because on a alpha the limbs are large but we normally need
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* integers of n bits - So we should change this to bits (or bytes).
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*
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* But mpi_alloc is used in a lot of places :-)
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*/
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MPI mpi_alloc(unsigned nlimbs)
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{
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MPI a;
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a = kmalloc(sizeof *a, GFP_KERNEL);
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if (!a)
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return a;
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if (nlimbs) {
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a->d = mpi_alloc_limb_space(nlimbs);
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if (!a->d) {
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kfree(a);
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return NULL;
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}
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} else {
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a->d = NULL;
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}
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a->alloced = nlimbs;
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a->nlimbs = 0;
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a->sign = 0;
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a->flags = 0;
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a->nbits = 0;
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return a;
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}
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EXPORT_SYMBOL_GPL(mpi_alloc);
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mpi_ptr_t mpi_alloc_limb_space(unsigned nlimbs)
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{
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size_t len = nlimbs * sizeof(mpi_limb_t);
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if (!len)
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return NULL;
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return kmalloc(len, GFP_KERNEL);
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}
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void mpi_free_limb_space(mpi_ptr_t a)
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{
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if (!a)
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return;
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kfree_sensitive(a);
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}
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void mpi_assign_limb_space(MPI a, mpi_ptr_t ap, unsigned nlimbs)
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{
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mpi_free_limb_space(a->d);
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a->d = ap;
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a->alloced = nlimbs;
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}
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/****************
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* Resize the array of A to NLIMBS. the additional space is cleared
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* (set to 0) [done by m_realloc()]
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*/
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int mpi_resize(MPI a, unsigned nlimbs)
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{
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void *p;
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if (nlimbs <= a->alloced)
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return 0; /* no need to do it */
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if (a->d) {
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p = kcalloc(nlimbs, sizeof(mpi_limb_t), GFP_KERNEL);
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if (!p)
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return -ENOMEM;
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memcpy(p, a->d, a->alloced * sizeof(mpi_limb_t));
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kfree_sensitive(a->d);
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a->d = p;
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} else {
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a->d = kcalloc(nlimbs, sizeof(mpi_limb_t), GFP_KERNEL);
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if (!a->d)
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return -ENOMEM;
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}
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a->alloced = nlimbs;
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return 0;
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}
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void mpi_clear(MPI a)
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{
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if (!a)
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return;
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a->nlimbs = 0;
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a->flags = 0;
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}
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EXPORT_SYMBOL_GPL(mpi_clear);
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void mpi_free(MPI a)
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{
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if (!a)
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return;
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if (a->flags & 4)
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kfree_sensitive(a->d);
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else
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mpi_free_limb_space(a->d);
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if (a->flags & ~7)
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pr_info("invalid flag value in mpi\n");
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kfree(a);
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}
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EXPORT_SYMBOL_GPL(mpi_free);
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/****************
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* Note: This copy function should not interpret the MPI
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* but copy it transparently.
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*/
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MPI mpi_copy(MPI a)
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{
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int i;
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MPI b;
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if (a) {
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b = mpi_alloc(a->nlimbs);
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b->nlimbs = a->nlimbs;
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b->sign = a->sign;
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b->flags = a->flags;
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b->flags &= ~(16|32); /* Reset the immutable and constant flags. */
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for (i = 0; i < b->nlimbs; i++)
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b->d[i] = a->d[i];
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} else
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b = NULL;
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return b;
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}
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/****************
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* This function allocates an MPI which is optimized to hold
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* a value as large as the one given in the argument and allocates it
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* with the same flags as A.
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*/
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MPI mpi_alloc_like(MPI a)
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{
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MPI b;
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if (a) {
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b = mpi_alloc(a->nlimbs);
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b->nlimbs = 0;
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b->sign = 0;
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b->flags = a->flags;
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} else
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b = NULL;
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return b;
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}
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/* Set U into W and release U. If W is NULL only U will be released. */
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void mpi_snatch(MPI w, MPI u)
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{
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if (w) {
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mpi_assign_limb_space(w, u->d, u->alloced);
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w->nlimbs = u->nlimbs;
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w->sign = u->sign;
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w->flags = u->flags;
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u->alloced = 0;
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u->nlimbs = 0;
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u->d = NULL;
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}
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mpi_free(u);
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}
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MPI mpi_set(MPI w, MPI u)
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{
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mpi_ptr_t wp, up;
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mpi_size_t usize = u->nlimbs;
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int usign = u->sign;
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if (!w)
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w = mpi_alloc(mpi_get_nlimbs(u));
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RESIZE_IF_NEEDED(w, usize);
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wp = w->d;
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up = u->d;
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MPN_COPY(wp, up, usize);
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w->nlimbs = usize;
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w->flags = u->flags;
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w->flags &= ~(16|32); /* Reset the immutable and constant flags. */
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w->sign = usign;
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return w;
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}
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EXPORT_SYMBOL_GPL(mpi_set);
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MPI mpi_set_ui(MPI w, unsigned long u)
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{
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if (!w)
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w = mpi_alloc(1);
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/* FIXME: If U is 0 we have no need to resize and thus possible
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* allocating the limbs.
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*/
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RESIZE_IF_NEEDED(w, 1);
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w->d[0] = u;
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w->nlimbs = u ? 1 : 0;
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w->sign = 0;
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w->flags = 0;
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return w;
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}
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EXPORT_SYMBOL_GPL(mpi_set_ui);
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MPI mpi_alloc_set_ui(unsigned long u)
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{
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MPI w = mpi_alloc(1);
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w->d[0] = u;
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w->nlimbs = u ? 1 : 0;
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w->sign = 0;
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return w;
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}
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/****************
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* Swap the value of A and B, when SWAP is 1.
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* Leave the value when SWAP is 0.
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* This implementation should be constant-time regardless of SWAP.
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*/
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void mpi_swap_cond(MPI a, MPI b, unsigned long swap)
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{
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mpi_size_t i;
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mpi_size_t nlimbs;
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mpi_limb_t mask = ((mpi_limb_t)0) - swap;
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mpi_limb_t x;
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if (a->alloced > b->alloced)
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nlimbs = b->alloced;
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else
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nlimbs = a->alloced;
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if (a->nlimbs > nlimbs || b->nlimbs > nlimbs)
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return;
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for (i = 0; i < nlimbs; i++) {
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x = mask & (a->d[i] ^ b->d[i]);
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a->d[i] = a->d[i] ^ x;
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b->d[i] = b->d[i] ^ x;
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}
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x = mask & (a->nlimbs ^ b->nlimbs);
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a->nlimbs = a->nlimbs ^ x;
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b->nlimbs = b->nlimbs ^ x;
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x = mask & (a->sign ^ b->sign);
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a->sign = a->sign ^ x;
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b->sign = b->sign ^ x;
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}
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MODULE_DESCRIPTION("Multiprecision maths library");
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MODULE_LICENSE("GPL");
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