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/* SPDX-License-Identifier: GPL-2.0-or-later */
/* mpi-inline.h - Internal to the Multi Precision Integers
* Copyright (C) 1994, 1996, 1998, 1999 Free Software Foundation, Inc.
*
* This file is part of GnuPG.
*
* 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.
* The GNU MP Library itself is published under the LGPL;
* however I decided to publish this code under the plain GPL.
*/
#ifndef G10_MPI_INLINE_H
#define G10_MPI_INLINE_H
#ifndef G10_MPI_INLINE_DECL
#define G10_MPI_INLINE_DECL static inline
#endif
G10_MPI_INLINE_DECL mpi_limb_t
mpihelp_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
mpihelp_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 = mpihelp_add_n(res_ptr, s1_ptr, s2_ptr, s2_size);
if (s1_size - s2_size)
cy = mpihelp_add_1(res_ptr + s2_size, s1_ptr + s2_size,
s1_size - s2_size, cy);
return cy;
}
G10_MPI_INLINE_DECL mpi_limb_t
mpihelp_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
mpihelp_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 = mpihelp_sub_n(res_ptr, s1_ptr, s2_ptr, s2_size);
if (s1_size - s2_size)
cy = mpihelp_sub_1(res_ptr + s2_size, s1_ptr + s2_size,
s1_size - s2_size, cy);
return cy;
}
#endif /*G10_MPI_INLINE_H */
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