1*4882a593Smuzhiyun /* SPDX-License-Identifier: GPL-2.0-or-later */
2*4882a593Smuzhiyun /* mpi-inline.h - Internal to the Multi Precision Integers
3*4882a593Smuzhiyun * Copyright (C) 1994, 1996, 1998, 1999 Free Software Foundation, Inc.
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * This file is part of GnuPG.
6*4882a593Smuzhiyun *
7*4882a593Smuzhiyun * Note: This code is heavily based on the GNU MP Library.
8*4882a593Smuzhiyun * Actually it's the same code with only minor changes in the
9*4882a593Smuzhiyun * way the data is stored; this is to support the abstraction
10*4882a593Smuzhiyun * of an optional secure memory allocation which may be used
11*4882a593Smuzhiyun * to avoid revealing of sensitive data due to paging etc.
12*4882a593Smuzhiyun * The GNU MP Library itself is published under the LGPL;
13*4882a593Smuzhiyun * however I decided to publish this code under the plain GPL.
14*4882a593Smuzhiyun */
15*4882a593Smuzhiyun
16*4882a593Smuzhiyun #ifndef G10_MPI_INLINE_H
17*4882a593Smuzhiyun #define G10_MPI_INLINE_H
18*4882a593Smuzhiyun
19*4882a593Smuzhiyun #ifndef G10_MPI_INLINE_DECL
20*4882a593Smuzhiyun #define G10_MPI_INLINE_DECL static inline
21*4882a593Smuzhiyun #endif
22*4882a593Smuzhiyun
23*4882a593Smuzhiyun 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)24*4882a593Smuzhiyun mpihelp_add_1(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr,
25*4882a593Smuzhiyun mpi_size_t s1_size, mpi_limb_t s2_limb)
26*4882a593Smuzhiyun {
27*4882a593Smuzhiyun mpi_limb_t x;
28*4882a593Smuzhiyun
29*4882a593Smuzhiyun x = *s1_ptr++;
30*4882a593Smuzhiyun s2_limb += x;
31*4882a593Smuzhiyun *res_ptr++ = s2_limb;
32*4882a593Smuzhiyun if (s2_limb < x) { /* sum is less than the left operand: handle carry */
33*4882a593Smuzhiyun while (--s1_size) {
34*4882a593Smuzhiyun x = *s1_ptr++ + 1; /* add carry */
35*4882a593Smuzhiyun *res_ptr++ = x; /* and store */
36*4882a593Smuzhiyun if (x) /* not 0 (no overflow): we can stop */
37*4882a593Smuzhiyun goto leave;
38*4882a593Smuzhiyun }
39*4882a593Smuzhiyun return 1; /* return carry (size of s1 to small) */
40*4882a593Smuzhiyun }
41*4882a593Smuzhiyun
42*4882a593Smuzhiyun leave:
43*4882a593Smuzhiyun if (res_ptr != s1_ptr) { /* not the same variable */
44*4882a593Smuzhiyun mpi_size_t i; /* copy the rest */
45*4882a593Smuzhiyun for (i = 0; i < s1_size - 1; i++)
46*4882a593Smuzhiyun res_ptr[i] = s1_ptr[i];
47*4882a593Smuzhiyun }
48*4882a593Smuzhiyun return 0; /* no carry */
49*4882a593Smuzhiyun }
50*4882a593Smuzhiyun
51*4882a593Smuzhiyun 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)52*4882a593Smuzhiyun mpihelp_add(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr, mpi_size_t s1_size,
53*4882a593Smuzhiyun mpi_ptr_t s2_ptr, mpi_size_t s2_size)
54*4882a593Smuzhiyun {
55*4882a593Smuzhiyun mpi_limb_t cy = 0;
56*4882a593Smuzhiyun
57*4882a593Smuzhiyun if (s2_size)
58*4882a593Smuzhiyun cy = mpihelp_add_n(res_ptr, s1_ptr, s2_ptr, s2_size);
59*4882a593Smuzhiyun
60*4882a593Smuzhiyun if (s1_size - s2_size)
61*4882a593Smuzhiyun cy = mpihelp_add_1(res_ptr + s2_size, s1_ptr + s2_size,
62*4882a593Smuzhiyun s1_size - s2_size, cy);
63*4882a593Smuzhiyun return cy;
64*4882a593Smuzhiyun }
65*4882a593Smuzhiyun
66*4882a593Smuzhiyun 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)67*4882a593Smuzhiyun mpihelp_sub_1(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr,
68*4882a593Smuzhiyun mpi_size_t s1_size, mpi_limb_t s2_limb)
69*4882a593Smuzhiyun {
70*4882a593Smuzhiyun mpi_limb_t x;
71*4882a593Smuzhiyun
72*4882a593Smuzhiyun x = *s1_ptr++;
73*4882a593Smuzhiyun s2_limb = x - s2_limb;
74*4882a593Smuzhiyun *res_ptr++ = s2_limb;
75*4882a593Smuzhiyun if (s2_limb > x) {
76*4882a593Smuzhiyun while (--s1_size) {
77*4882a593Smuzhiyun x = *s1_ptr++;
78*4882a593Smuzhiyun *res_ptr++ = x - 1;
79*4882a593Smuzhiyun if (x)
80*4882a593Smuzhiyun goto leave;
81*4882a593Smuzhiyun }
82*4882a593Smuzhiyun return 1;
83*4882a593Smuzhiyun }
84*4882a593Smuzhiyun
85*4882a593Smuzhiyun leave:
86*4882a593Smuzhiyun if (res_ptr != s1_ptr) {
87*4882a593Smuzhiyun mpi_size_t i;
88*4882a593Smuzhiyun for (i = 0; i < s1_size - 1; i++)
89*4882a593Smuzhiyun res_ptr[i] = s1_ptr[i];
90*4882a593Smuzhiyun }
91*4882a593Smuzhiyun return 0;
92*4882a593Smuzhiyun }
93*4882a593Smuzhiyun
94*4882a593Smuzhiyun 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)95*4882a593Smuzhiyun mpihelp_sub(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr, mpi_size_t s1_size,
96*4882a593Smuzhiyun mpi_ptr_t s2_ptr, mpi_size_t s2_size)
97*4882a593Smuzhiyun {
98*4882a593Smuzhiyun mpi_limb_t cy = 0;
99*4882a593Smuzhiyun
100*4882a593Smuzhiyun if (s2_size)
101*4882a593Smuzhiyun cy = mpihelp_sub_n(res_ptr, s1_ptr, s2_ptr, s2_size);
102*4882a593Smuzhiyun
103*4882a593Smuzhiyun if (s1_size - s2_size)
104*4882a593Smuzhiyun cy = mpihelp_sub_1(res_ptr + s2_size, s1_ptr + s2_size,
105*4882a593Smuzhiyun s1_size - s2_size, cy);
106*4882a593Smuzhiyun return cy;
107*4882a593Smuzhiyun }
108*4882a593Smuzhiyun
109*4882a593Smuzhiyun #endif /*G10_MPI_INLINE_H */
110