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/* mpi-inline.h - Internal to the Multi Precision Integers
* Copyright (C) 1994, 1996, 1998, 1999,
* 2001, 2002 Free Software Foundation, Inc.
*
* This file is part of Libgcrypt.
*
* Libgcrypt is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* Libgcrypt is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*
* 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.
*/
#ifndef G10_MPI_INLINE_H
#define G10_MPI_INLINE_H
#ifndef G10_MPI_INLINE_DECL
#define G10_MPI_INLINE_DECL extern __inline__
#endif
G10_MPI_INLINE_DECL mpi_limb_t
_gcry_mpih_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
_gcry_mpih_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 = _gcry_mpih_add_n( res_ptr, s1_ptr, s2_ptr, s2_size );
if( s1_size - s2_size )
cy = _gcry_mpih_add_1( res_ptr + s2_size, s1_ptr + s2_size,
s1_size - s2_size, cy);
return cy;
}
G10_MPI_INLINE_DECL mpi_limb_t
_gcry_mpih_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
_gcry_mpih_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 = _gcry_mpih_sub_n(res_ptr, s1_ptr, s2_ptr, s2_size);
if( s1_size - s2_size )
cy = _gcry_mpih_sub_1(res_ptr + s2_size, s1_ptr + s2_size,
s1_size - s2_size, cy);
return cy;
}
/****************
* Compare OP1_PTR/OP1_SIZE with OP2_PTR/OP2_SIZE.
* There are no restrictions on the relative sizes of
* the two arguments.
* Return 1 if OP1 > OP2, 0 if they are equal, and -1 if OP1 < OP2.
*/
G10_MPI_INLINE_DECL int
_gcry_mpih_cmp( mpi_ptr_t op1_ptr, mpi_ptr_t op2_ptr, mpi_size_t size )
{
mpi_size_t i;
mpi_limb_t op1_word, op2_word;
for( i = size - 1; i >= 0 ; i--) {
op1_word = op1_ptr[i];
op2_word = op2_ptr[i];
if( op1_word != op2_word )
goto diff;
}
return 0;
diff:
/* This can *not* be simplified to
* op2_word - op2_word
* since that expression might give signed overflow. */
return (op1_word > op2_word) ? 1 : -1;
}
#endif /*G10_MPI_INLINE_H*/
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