cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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mpi-inline.h (2698B)

      1/* SPDX-License-Identifier: GPL-2.0-or-later */
      2/* mpi-inline.h  -  Internal to the Multi Precision Integers
      3 *	Copyright (C) 1994, 1996, 1998, 1999 Free Software Foundation, Inc.
      4 *
      5 * This file is part of GnuPG.
      6 *
      7 * Note: This code is heavily based on the GNU MP Library.
      8 *	 Actually it's the same code with only minor changes in the
      9 *	 way the data is stored; this is to support the abstraction
     10 *	 of an optional secure memory allocation which may be used
     11 *	 to avoid revealing of sensitive data due to paging etc.
     12 *	 The GNU MP Library itself is published under the LGPL;
     13 *	 however I decided to publish this code under the plain GPL.
     14 */
     15
     16#ifndef G10_MPI_INLINE_H
     17#define G10_MPI_INLINE_H
     18
     19#ifndef G10_MPI_INLINE_DECL
     20#define G10_MPI_INLINE_DECL  static inline
     21#endif
     22
     23G10_MPI_INLINE_DECL mpi_limb_t
     24mpihelp_add_1(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr,
     25	      mpi_size_t s1_size, mpi_limb_t s2_limb)
     26{
     27	mpi_limb_t x;
     28
     29	x = *s1_ptr++;
     30	s2_limb += x;
     31	*res_ptr++ = s2_limb;
     32	if (s2_limb < x) {	/* sum is less than the left operand: handle carry */
     33		while (--s1_size) {
     34			x = *s1_ptr++ + 1;	/* add carry */
     35			*res_ptr++ = x;	/* and store */
     36			if (x)	/* not 0 (no overflow): we can stop */
     37				goto leave;
     38		}
     39		return 1;	/* return carry (size of s1 to small) */
     40	}
     41
     42leave:
     43	if (res_ptr != s1_ptr) {	/* not the same variable */
     44		mpi_size_t i;	/* copy the rest */
     45		for (i = 0; i < s1_size - 1; i++)
     46			res_ptr[i] = s1_ptr[i];
     47	}
     48	return 0;		/* no carry */
     49}
     50
     51G10_MPI_INLINE_DECL mpi_limb_t
     52mpihelp_add(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr, mpi_size_t s1_size,
     53	    mpi_ptr_t s2_ptr, mpi_size_t s2_size)
     54{
     55	mpi_limb_t cy = 0;
     56
     57	if (s2_size)
     58		cy = mpihelp_add_n(res_ptr, s1_ptr, s2_ptr, s2_size);
     59
     60	if (s1_size - s2_size)
     61		cy = mpihelp_add_1(res_ptr + s2_size, s1_ptr + s2_size,
     62				   s1_size - s2_size, cy);
     63	return cy;
     64}
     65
     66G10_MPI_INLINE_DECL mpi_limb_t
     67mpihelp_sub_1(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr,
     68	      mpi_size_t s1_size, mpi_limb_t s2_limb)
     69{
     70	mpi_limb_t x;
     71
     72	x = *s1_ptr++;
     73	s2_limb = x - s2_limb;
     74	*res_ptr++ = s2_limb;
     75	if (s2_limb > x) {
     76		while (--s1_size) {
     77			x = *s1_ptr++;
     78			*res_ptr++ = x - 1;
     79			if (x)
     80				goto leave;
     81		}
     82		return 1;
     83	}
     84
     85leave:
     86	if (res_ptr != s1_ptr) {
     87		mpi_size_t i;
     88		for (i = 0; i < s1_size - 1; i++)
     89			res_ptr[i] = s1_ptr[i];
     90	}
     91	return 0;
     92}
     93
     94G10_MPI_INLINE_DECL mpi_limb_t
     95mpihelp_sub(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr, mpi_size_t s1_size,
     96	    mpi_ptr_t s2_ptr, mpi_size_t s2_size)
     97{
     98	mpi_limb_t cy = 0;
     99
    100	if (s2_size)
    101		cy = mpihelp_sub_n(res_ptr, s1_ptr, s2_ptr, s2_size);
    102
    103	if (s1_size - s2_size)
    104		cy = mpihelp_sub_1(res_ptr + s2_size, s1_ptr + s2_size,
    105				   s1_size - s2_size, cy);
    106	return cy;
    107}
    108
    109#endif /*G10_MPI_INLINE_H */