mirror of git://git.gnupg.org/gnupg.git
134 lines
3.6 KiB
C
134 lines
3.6 KiB
C
/* 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 3 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, see <http://www.gnu.org/licenses/>.
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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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/* Starting with gcc 4.3 "extern inline" conforms in c99 mode to the
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c99 semantics. To keep the useful old semantics we use an
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attribute. */
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#ifndef G10_MPI_INLINE_DECL
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# ifdef __GNUC_STDC_INLINE__
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# define G10_MPI_INLINE_DECL extern inline __attribute__ ((__gnu_inline__))
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# else
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# define G10_MPI_INLINE_DECL extern __inline__
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# endif
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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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