// SPDX-License-Identifier: GPL-2.0-or-later /* mpihelp-div.c - MPI helper functions * Copyright (C) 1994, 1996 Free Software Foundation, Inc. * Copyright (C) 1998, 1999 Free Software Foundation, Inc. * * This file is part of GnuPG. * * 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 "mpi-internal.h" #include "longlong.h" #ifndef UMUL_TIME #define UMUL_TIME … #endif #ifndef UDIV_TIME #define UDIV_TIME … #endif mpi_limb_t mpihelp_mod_1(mpi_ptr_t dividend_ptr, mpi_size_t dividend_size, mpi_limb_t divisor_limb) { … } /* Divide num (NP/NSIZE) by den (DP/DSIZE) and write * the NSIZE-DSIZE least significant quotient limbs at QP * and the DSIZE long remainder at NP. If QEXTRA_LIMBS is * non-zero, generate that many fraction bits and append them after the * other quotient limbs. * Return the most significant limb of the quotient, this is always 0 or 1. * * Preconditions: * 0. NSIZE >= DSIZE. * 1. The most significant bit of the divisor must be set. * 2. QP must either not overlap with the input operands at all, or * QP + DSIZE >= NP must hold true. (This means that it's * possible to put the quotient in the high part of NUM, right after the * remainder in NUM. * 3. NSIZE >= DSIZE, even if QEXTRA_LIMBS is non-zero. */ mpi_limb_t mpihelp_divrem(mpi_ptr_t qp, mpi_size_t qextra_limbs, mpi_ptr_t np, mpi_size_t nsize, mpi_ptr_t dp, mpi_size_t dsize) { … } /**************** * Divide (DIVIDEND_PTR,,DIVIDEND_SIZE) by DIVISOR_LIMB. * Write DIVIDEND_SIZE limbs of quotient at QUOT_PTR. * Return the single-limb remainder. * There are no constraints on the value of the divisor. * * QUOT_PTR and DIVIDEND_PTR might point to the same limb. */ mpi_limb_t mpihelp_divmod_1(mpi_ptr_t quot_ptr, mpi_ptr_t dividend_ptr, mpi_size_t dividend_size, mpi_limb_t divisor_limb) { … }
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