/* 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, see <https://www.gnu.org/licenses/>.

 * SPDX-License-Identifier: LGPL-2.1-or-later

 *

 * 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

/* Starting with gcc 4.3 "extern inline" conforms in c99 mode to the

   c99 semantics.  To keep the useful old semantics we use an

   attribute.  */

#ifndef G10_MPI_INLINE_DECL

# ifdef __GNUC_STDC_INLINE__

#  define G10_MPI_INLINE_DECL  extern inline __attribute__ ((__gnu_inline__))

# else

#  define G10_MPI_INLINE_DECL  extern __inline__

# endif

#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*/