/* SPDX-License-Identifier: GPL-2.0-or-later */
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/* mpi-inline.h - Internal to the Multi Precision Integers
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* Copyright (C) 1994, 1996, 1998, 1999 Free Software Foundation, Inc.
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*
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* This file is part of GnuPG.
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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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* The GNU MP Library itself is published under the LGPL;
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* however I decided to publish this code under the plain GPL.
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*/
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#ifndef G10_MPI_INLINE_H
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#define G10_MPI_INLINE_H
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#ifndef G10_MPI_INLINE_DECL
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#define G10_MPI_INLINE_DECL static inline
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#endif
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G10_MPI_INLINE_DECL mpi_limb_t
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mpihelp_add_1(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr,
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mpi_size_t s1_size, mpi_limb_t s2_limb)
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{
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mpi_limb_t x;
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x = *s1_ptr++;
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s2_limb += x;
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*res_ptr++ = s2_limb;
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if (s2_limb < x) { /* sum is less than the left operand: handle carry */
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while (--s1_size) {
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x = *s1_ptr++ + 1; /* add carry */
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*res_ptr++ = x; /* and store */
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if (x) /* not 0 (no overflow): we can stop */
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goto leave;
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}
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return 1; /* return carry (size of s1 to small) */
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}
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leave:
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if (res_ptr != s1_ptr) { /* not the same variable */
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mpi_size_t i; /* copy the rest */
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for (i = 0; i < s1_size - 1; i++)
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res_ptr[i] = s1_ptr[i];
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}
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return 0; /* no carry */
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}
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G10_MPI_INLINE_DECL mpi_limb_t
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mpihelp_add(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr, mpi_size_t s1_size,
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mpi_ptr_t s2_ptr, mpi_size_t s2_size)
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{
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mpi_limb_t cy = 0;
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if (s2_size)
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cy = mpihelp_add_n(res_ptr, s1_ptr, s2_ptr, s2_size);
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if (s1_size - s2_size)
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cy = mpihelp_add_1(res_ptr + s2_size, s1_ptr + s2_size,
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s1_size - s2_size, cy);
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return cy;
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}
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G10_MPI_INLINE_DECL mpi_limb_t
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mpihelp_sub_1(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr,
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mpi_size_t s1_size, mpi_limb_t s2_limb)
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{
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mpi_limb_t x;
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x = *s1_ptr++;
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s2_limb = x - s2_limb;
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*res_ptr++ = s2_limb;
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if (s2_limb > x) {
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while (--s1_size) {
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x = *s1_ptr++;
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*res_ptr++ = x - 1;
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if (x)
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goto leave;
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}
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return 1;
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}
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leave:
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if (res_ptr != s1_ptr) {
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mpi_size_t i;
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for (i = 0; i < s1_size - 1; i++)
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res_ptr[i] = s1_ptr[i];
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}
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return 0;
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}
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G10_MPI_INLINE_DECL mpi_limb_t
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mpihelp_sub(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr, mpi_size_t s1_size,
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mpi_ptr_t s2_ptr, mpi_size_t s2_size)
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{
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mpi_limb_t cy = 0;
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if (s2_size)
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cy = mpihelp_sub_n(res_ptr, s1_ptr, s2_ptr, s2_size);
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if (s1_size - s2_size)
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cy = mpihelp_sub_1(res_ptr + s2_size, s1_ptr + s2_size,
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s1_size - s2_size, cy);
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return cy;
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}
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#endif /*G10_MPI_INLINE_H */
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