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fca5cb4dd2
This partially reverts commit a8ea8bdd9d.
Most of it is no longer needed since sm2 has been removed. However,
the following functions have been kept as they have developed other
uses:
mpi_copy
mpi_mod
mpi_test_bit
mpi_set_bit
mpi_rshift
mpi_add
mpi_sub
mpi_addm
mpi_subm
mpi_mul
mpi_mulm
mpi_tdiv_r
mpi_fdiv_r
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
104 lines
2.3 KiB
C
104 lines
2.3 KiB
C
/* mpi-add.c - MPI functions
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* Copyright (C) 1994, 1996, 1998, 2001, 2002,
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* 2003 Free Software Foundation, Inc.
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*
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* This file is part of Libgcrypt.
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*
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* Note: This code is heavily based on the GNU MP Library.
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* Actually it's the same code with only minor changes in the
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* way the data is stored; this is to support the abstraction
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* of an optional secure memory allocation which may be used
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* to avoid revealing of sensitive data due to paging etc.
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*/
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#include "mpi-internal.h"
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void mpi_add(MPI w, MPI u, MPI v)
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{
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mpi_ptr_t wp, up, vp;
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mpi_size_t usize, vsize, wsize;
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int usign, vsign, wsign;
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if (u->nlimbs < v->nlimbs) { /* Swap U and V. */
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usize = v->nlimbs;
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usign = v->sign;
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vsize = u->nlimbs;
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vsign = u->sign;
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wsize = usize + 1;
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RESIZE_IF_NEEDED(w, wsize);
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/* These must be after realloc (u or v may be the same as w). */
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up = v->d;
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vp = u->d;
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} else {
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usize = u->nlimbs;
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usign = u->sign;
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vsize = v->nlimbs;
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vsign = v->sign;
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wsize = usize + 1;
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RESIZE_IF_NEEDED(w, wsize);
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/* These must be after realloc (u or v may be the same as w). */
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up = u->d;
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vp = v->d;
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}
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wp = w->d;
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wsign = 0;
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if (!vsize) { /* simple */
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MPN_COPY(wp, up, usize);
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wsize = usize;
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wsign = usign;
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} else if (usign != vsign) { /* different sign */
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/* This test is right since USIZE >= VSIZE */
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if (usize != vsize) {
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mpihelp_sub(wp, up, usize, vp, vsize);
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wsize = usize;
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MPN_NORMALIZE(wp, wsize);
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wsign = usign;
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} else if (mpihelp_cmp(up, vp, usize) < 0) {
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mpihelp_sub_n(wp, vp, up, usize);
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wsize = usize;
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MPN_NORMALIZE(wp, wsize);
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if (!usign)
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wsign = 1;
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} else {
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mpihelp_sub_n(wp, up, vp, usize);
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wsize = usize;
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MPN_NORMALIZE(wp, wsize);
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if (usign)
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wsign = 1;
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}
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} else { /* U and V have same sign. Add them. */
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mpi_limb_t cy = mpihelp_add(wp, up, usize, vp, vsize);
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wp[usize] = cy;
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wsize = usize + cy;
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if (usign)
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wsign = 1;
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}
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w->nlimbs = wsize;
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w->sign = wsign;
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}
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EXPORT_SYMBOL_GPL(mpi_add);
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void mpi_sub(MPI w, MPI u, MPI v)
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{
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MPI vv = mpi_copy(v);
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vv->sign = !vv->sign;
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mpi_add(w, u, vv);
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mpi_free(vv);
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}
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EXPORT_SYMBOL_GPL(mpi_sub);
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void mpi_addm(MPI w, MPI u, MPI v, MPI m)
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{
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mpi_add(w, u, v);
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mpi_mod(w, w, m);
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}
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EXPORT_SYMBOL_GPL(mpi_addm);
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void mpi_subm(MPI w, MPI u, MPI v, MPI m)
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{
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mpi_sub(w, u, v);
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mpi_mod(w, w, m);
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}
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EXPORT_SYMBOL_GPL(mpi_subm);
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