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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
commit | 2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch) | |
tree | 848558de17fb3008cdf4d861b01ac7781903ce39 /lib/mpi/mpi-bit.c | |
parent | Initial commit. (diff) | |
download | linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip |
Adding upstream version 6.1.76.upstream/6.1.76
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'lib/mpi/mpi-bit.c')
-rw-r--r-- | lib/mpi/mpi-bit.c | 308 |
1 files changed, 308 insertions, 0 deletions
diff --git a/lib/mpi/mpi-bit.c b/lib/mpi/mpi-bit.c new file mode 100644 index 000000000..070ba784c --- /dev/null +++ b/lib/mpi/mpi-bit.c @@ -0,0 +1,308 @@ +/* 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); +} +EXPORT_SYMBOL_GPL(mpi_rshift); + +/**************** + * 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); +} |