154 lines
4 KiB
C
154 lines
4 KiB
C
/* mpi-inline.h - Internal to the Multi Precision Integers
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* Copyright (C) 1994, 1996, 1998, 1999,
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* 2001, 2002 Free Software Foundation, Inc.
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*
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* This file is part of Libgcrypt.
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*
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* Libgcrypt is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation; either version 2.1 of
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* the License, or (at your option) any later version.
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*
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* Libgcrypt 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 Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License 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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*/
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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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_gcry_mpih_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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_gcry_mpih_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 = _gcry_mpih_add_n( res_ptr, s1_ptr, s2_ptr, s2_size );
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if( s1_size - s2_size )
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cy = _gcry_mpih_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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_gcry_mpih_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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_gcry_mpih_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 = _gcry_mpih_sub_n(res_ptr, s1_ptr, s2_ptr, s2_size);
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if( s1_size - s2_size )
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cy = _gcry_mpih_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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/****************
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* Compare OP1_PTR/OP1_SIZE with OP2_PTR/OP2_SIZE.
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* There are no restrictions on the relative sizes of
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* the two arguments.
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* Return 1 if OP1 > OP2, 0 if they are equal, and -1 if OP1 < OP2.
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*/
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G10_MPI_INLINE_DECL int
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_gcry_mpih_cmp( mpi_ptr_t op1_ptr, mpi_ptr_t op2_ptr, mpi_size_t size )
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{
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mpi_size_t i;
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mpi_limb_t op1_word, op2_word;
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for( i = size - 1; i >= 0 ; i--) {
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op1_word = op1_ptr[i];
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op2_word = op2_ptr[i];
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if( op1_word != op2_word )
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goto diff;
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}
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return 0;
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diff:
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/* This can *not* be simplified to
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* op2_word - op2_word
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* since that expression might give signed overflow. */
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return (op1_word > op2_word) ? 1 : -1;
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}
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#endif /*G10_MPI_INLINE_H*/
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