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Diffstat (limited to 'lib/mpi/mpi-div.c')
| -rw-r--r-- | lib/mpi/mpi-div.c | 338 |
1 files changed, 0 insertions, 338 deletions
diff --git a/lib/mpi/mpi-div.c b/lib/mpi/mpi-div.c deleted file mode 100644 index f68cbbb4d4a4..000000000000 --- a/lib/mpi/mpi-div.c +++ /dev/null @@ -1,338 +0,0 @@ -/* mpi-div.c - MPI functions - * Copyright (C) 1994, 1996 Free Software Foundation, Inc. - * Copyright (C) 1998, 1999, 2000, 2001 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 - * - * Note: This code is heavily based on the GNU MP Library. - * Actually it's the same code with only minor changes in the - * way the data is stored; this is to support the abstraction - * of an optional secure memory allocation which may be used - * to avoid revealing of sensitive data due to paging etc. - * The GNU MP Library itself is published under the LGPL; - * however I decided to publish this code under the plain GPL. - */ - -#include <linux/string.h> -#include "mpi-internal.h" -#include "longlong.h" - -int mpi_fdiv_r(MPI rem, MPI dividend, MPI divisor) -{ - int rc = -ENOMEM; - int divisor_sign = divisor->sign; - MPI temp_divisor = NULL; - - /* We need the original value of the divisor after the remainder has been - * preliminary calculated. We have to copy it to temporary space if it's - * the same variable as REM. */ - if (rem == divisor) { - if (mpi_copy(&temp_divisor, divisor) < 0) - goto nomem; - divisor = temp_divisor; - } - - if (mpi_tdiv_qr(NULL, rem, dividend, divisor) < 0) - goto nomem; - if (((divisor_sign ? 1 : 0) ^ (dividend->sign ? 1 : 0)) && rem->nlimbs) - if (mpi_add(rem, rem, divisor) < 0) - goto nomem; - - rc = 0; - -nomem: - if (temp_divisor) - mpi_free(temp_divisor); - return rc; -} - -/**************** - * Division rounding the quotient towards -infinity. - * The remainder gets the same sign as the denominator. - * rem is optional - */ - -ulong mpi_fdiv_r_ui(MPI rem, MPI dividend, ulong divisor) -{ - mpi_limb_t rlimb; - - rlimb = mpihelp_mod_1(dividend->d, dividend->nlimbs, divisor); - if (rlimb && dividend->sign) - rlimb = divisor - rlimb; - - if (rem) { - rem->d[0] = rlimb; - rem->nlimbs = rlimb ? 1 : 0; - } - return rlimb; -} - -int mpi_fdiv_q(MPI quot, MPI dividend, MPI divisor) -{ - MPI tmp = mpi_alloc(mpi_get_nlimbs(quot)); - if (!tmp) - return -ENOMEM; - mpi_fdiv_qr(quot, tmp, dividend, divisor); - mpi_free(tmp); - return 0; -} - -int mpi_fdiv_qr(MPI quot, MPI rem, MPI dividend, MPI divisor) -{ - int divisor_sign = divisor->sign; - MPI temp_divisor = NULL; - - if (quot == divisor || rem == divisor) { - if (mpi_copy(&temp_divisor, divisor) < 0) - return -ENOMEM; - divisor = temp_divisor; - } - - if (mpi_tdiv_qr(quot, rem, dividend, divisor) < 0) - goto nomem; - - if ((divisor_sign ^ dividend->sign) && rem->nlimbs) { - if (mpi_sub_ui(quot, quot, 1) < 0) - goto nomem; - if (mpi_add(rem, rem, divisor) < 0) - goto nomem; - } - - if (temp_divisor) - mpi_free(temp_divisor); - - return 0; - -nomem: - mpi_free(temp_divisor); - return -ENOMEM; -} - -/* If den == quot, den needs temporary storage. - * If den == rem, den needs temporary storage. - * If num == quot, num needs temporary storage. - * If den has temporary storage, it can be normalized while being copied, - * i.e no extra storage should be allocated. - */ - -int mpi_tdiv_r(MPI rem, MPI num, MPI den) -{ - return mpi_tdiv_qr(NULL, rem, num, den); -} - -int mpi_tdiv_qr(MPI quot, MPI rem, MPI num, MPI den) -{ - int rc = -ENOMEM; - mpi_ptr_t np, dp; - mpi_ptr_t qp, rp; - mpi_size_t nsize = num->nlimbs; - mpi_size_t dsize = den->nlimbs; - mpi_size_t qsize, rsize; - mpi_size_t sign_remainder = num->sign; - mpi_size_t sign_quotient = num->sign ^ den->sign; - unsigned normalization_steps; - mpi_limb_t q_limb; - mpi_ptr_t marker[5]; - int markidx = 0; - - if (!dsize) - return -EINVAL; - - memset(marker, 0, sizeof(marker)); - - /* Ensure space is enough for quotient and remainder. - * We need space for an extra limb in the remainder, because it's - * up-shifted (normalized) below. */ - rsize = nsize + 1; - if (mpi_resize(rem, rsize) < 0) - goto nomem; - - qsize = rsize - dsize; /* qsize cannot be bigger than this. */ - if (qsize <= 0) { - if (num != rem) { - rem->nlimbs = num->nlimbs; - rem->sign = num->sign; - MPN_COPY(rem->d, num->d, nsize); - } - if (quot) { - /* This needs to follow the assignment to rem, in case the - * numerator and quotient are the same. */ - quot->nlimbs = 0; - quot->sign = 0; - } - return 0; - } - - if (quot) - if (mpi_resize(quot, qsize) < 0) - goto nomem; - - /* Read pointers here, when reallocation is finished. */ - np = num->d; - dp = den->d; - rp = rem->d; - - /* Optimize division by a single-limb divisor. */ - if (dsize == 1) { - mpi_limb_t rlimb; - if (quot) { - qp = quot->d; - rlimb = mpihelp_divmod_1(qp, np, nsize, dp[0]); - qsize -= qp[qsize - 1] == 0; - quot->nlimbs = qsize; - quot->sign = sign_quotient; - } else - rlimb = mpihelp_mod_1(np, nsize, dp[0]); - rp[0] = rlimb; - rsize = rlimb != 0 ? 1 : 0; - rem->nlimbs = rsize; - rem->sign = sign_remainder; - return 0; - } - - if (quot) { - qp = quot->d; - /* Make sure QP and NP point to different objects. Otherwise the - * numerator would be gradually overwritten by the quotient limbs. */ - if (qp == np) { /* Copy NP object to temporary space. */ - np = marker[markidx++] = mpi_alloc_limb_space(nsize); - if (!np) - goto nomem; - MPN_COPY(np, qp, nsize); - } - } else /* Put quotient at top of remainder. */ - qp = rp + dsize; - - count_leading_zeros(normalization_steps, dp[dsize - 1]); - - /* Normalize the denominator, i.e. make its most significant bit set by - * shifting it NORMALIZATION_STEPS bits to the left. Also shift the - * numerator the same number of steps (to keep the quotient the same!). - */ - if (normalization_steps) { - mpi_ptr_t tp; - mpi_limb_t nlimb; - - /* Shift up the denominator setting the most significant bit of - * the most significant word. Use temporary storage not to clobber - * the original contents of the denominator. */ - tp = marker[markidx++] = mpi_alloc_limb_space(dsize); - if (!tp) - goto nomem; - mpihelp_lshift(tp, dp, dsize, normalization_steps); - dp = tp; - - /* Shift up the numerator, possibly introducing a new most - * significant word. Move the shifted numerator in the remainder - * meanwhile. */ - nlimb = mpihelp_lshift(rp, np, nsize, normalization_steps); - if (nlimb) { - rp[nsize] = nlimb; - rsize = nsize + 1; - } else - rsize = nsize; - } else { - /* The denominator is already normalized, as required. Copy it to - * temporary space if it overlaps with the quotient or remainder. */ - if (dp == rp || (quot && (dp == qp))) { - mpi_ptr_t tp; - - tp = marker[markidx++] = mpi_alloc_limb_space(dsize); - if (!tp) - goto nomem; - MPN_COPY(tp, dp, dsize); - dp = tp; - } - - /* Move the numerator to the remainder. */ - if (rp != np) - MPN_COPY(rp, np, nsize); - - rsize = nsize; - } - - q_limb = mpihelp_divrem(qp, 0, rp, rsize, dp, dsize); - - if (quot) { - qsize = rsize - dsize; - if (q_limb) { - qp[qsize] = q_limb; - qsize += 1; - } - - quot->nlimbs = qsize; - quot->sign = sign_quotient; - } - - rsize = dsize; - MPN_NORMALIZE(rp, rsize); - - if (normalization_steps && rsize) { - mpihelp_rshift(rp, rp, rsize, normalization_steps); - rsize -= rp[rsize - 1] == 0 ? 1 : 0; - } - - rem->nlimbs = rsize; - rem->sign = sign_remainder; - - rc = 0; -nomem: - while (markidx) - mpi_free_limb_space(marker[--markidx]); - return rc; -} - -int mpi_tdiv_q_2exp(MPI w, MPI u, unsigned count) -{ - mpi_size_t usize, wsize; - mpi_size_t limb_cnt; - - usize = u->nlimbs; - limb_cnt = count / BITS_PER_MPI_LIMB; - wsize = usize - limb_cnt; - if (limb_cnt >= usize) - w->nlimbs = 0; - else { - mpi_ptr_t wp; - mpi_ptr_t up; - - if (RESIZE_IF_NEEDED(w, wsize) < 0) - return -ENOMEM; - wp = w->d; - up = u->d; - - count %= BITS_PER_MPI_LIMB; - if (count) { - mpihelp_rshift(wp, up + limb_cnt, wsize, count); - wsize -= !wp[wsize - 1]; - } else { - MPN_COPY_INCR(wp, up + limb_cnt, wsize); - } - - w->nlimbs = wsize; - } - return 0; -} - -/**************** - * Check whether dividend is divisible by divisor - * (note: divisor must fit into a limb) - */ -int mpi_divisible_ui(MPI dividend, ulong divisor) -{ - return !mpihelp_mod_1(dividend->d, dividend->nlimbs, divisor); -} |