/* SPDX-License-Identifier: GPL-2.0-or-later */ /* mpi-inline.h - Internal to the Multi Precision Integers * Copyright (C) 1994, 1996, 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. */ #ifndef G10_MPI_INLINE_H #define G10_MPI_INLINE_H #ifndef G10_MPI_INLINE_DECL #define G10_MPI_INLINE_DECL static inline #endif G10_MPI_INLINE_DECL mpi_limb_t mpihelp_add_1(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr, mpi_size_t s1_size, mpi_limb_t s2_limb) { mpi_limb_t x; x = *s1_ptr++; s2_limb += x; *res_ptr++ = s2_limb; if (s2_limb < x) { /* sum is less than the left operand: handle carry */ while (--s1_size) { x = *s1_ptr++ + 1; /* add carry */ *res_ptr++ = x; /* and store */ if (x) /* not 0 (no overflow): we can stop */ goto leave; } return 1; /* return carry (size of s1 to small) */ } leave: if (res_ptr != s1_ptr) { /* not the same variable */ mpi_size_t i; /* copy the rest */ for (i = 0; i < s1_size - 1; i++) res_ptr[i] = s1_ptr[i]; } return 0; /* no carry */ } G10_MPI_INLINE_DECL mpi_limb_t mpihelp_add(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr, mpi_size_t s1_size, mpi_ptr_t s2_ptr, mpi_size_t s2_size) { mpi_limb_t cy = 0; if (s2_size) cy = mpihelp_add_n(res_ptr, s1_ptr, s2_ptr, s2_size); if (s1_size - s2_size) cy = mpihelp_add_1(res_ptr + s2_size, s1_ptr + s2_size, s1_size - s2_size, cy); return cy; } G10_MPI_INLINE_DECL mpi_limb_t mpihelp_sub_1(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr, mpi_size_t s1_size, mpi_limb_t s2_limb) { mpi_limb_t x; x = *s1_ptr++; s2_limb = x - s2_limb; *res_ptr++ = s2_limb; if (s2_limb > x) { while (--s1_size) { x = *s1_ptr++; *res_ptr++ = x - 1; if (x) goto leave; } return 1; } leave: if (res_ptr != s1_ptr) { mpi_size_t i; for (i = 0; i < s1_size - 1; i++) res_ptr[i] = s1_ptr[i]; } return 0; } G10_MPI_INLINE_DECL mpi_limb_t mpihelp_sub(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr, mpi_size_t s1_size, mpi_ptr_t s2_ptr, mpi_size_t s2_size) { mpi_limb_t cy = 0; if (s2_size) cy = mpihelp_sub_n(res_ptr, s1_ptr, s2_ptr, s2_size); if (s1_size - s2_size) cy = mpihelp_sub_1(res_ptr + s2_size, s1_ptr + s2_size, s1_size - s2_size, cy); return cy; } #endif /*G10_MPI_INLINE_H */