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122 lines
3.3 KiB
122 lines
3.3 KiB
/* 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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* GnuPG is free software; you can redistribute it and/or modify |
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* it under the terms of the GNU General Public License as published by |
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* the Free Software Foundation; either version 2 of the License, or |
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* (at your option) any later version. |
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* |
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* GnuPG is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU General Public License for more details. |
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* |
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* You should have received a copy of the GNU General Public License |
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* along with this program; if not, write to the Free Software |
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA |
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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 extern 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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