1 /* mpi-inline.h - Internal to the Multi Precision Integers
2 * Copyright (C) 1994, 1996, 1998, 1999 Free Software Foundation, Inc.
3 *
4 * This file is part of GnuPG.
5 *
6 * GnuPG is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * GnuPG is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
19 *
20 * Note: This code is heavily based on the GNU MP Library.
21 * Actually it's the same code with only minor changes in the
22 * way the data is stored; this is to support the abstraction
23 * of an optional secure memory allocation which may be used
24 * to avoid revealing of sensitive data due to paging etc.
25 * The GNU MP Library itself is published under the LGPL;
26 * however I decided to publish this code under the plain GPL.
27 */
28
29 #ifndef G10_MPI_INLINE_H
30 #define G10_MPI_INLINE_H
31
32 #ifndef G10_MPI_INLINE_DECL
33 #define G10_MPI_INLINE_DECL static inline
34 #endif
35
36 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)37 mpihelp_add_1(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr,
38 mpi_size_t s1_size, mpi_limb_t s2_limb)
39 {
40 mpi_limb_t x;
41
42 x = *s1_ptr++;
43 s2_limb += x;
44 *res_ptr++ = s2_limb;
45 if (s2_limb < x) { /* sum is less than the left operand: handle carry */
46 while (--s1_size) {
47 x = *s1_ptr++ + 1; /* add carry */
48 *res_ptr++ = x; /* and store */
49 if (x) /* not 0 (no overflow): we can stop */
50 goto leave;
51 }
52 return 1; /* return carry (size of s1 to small) */
53 }
54
55 leave:
56 if (res_ptr != s1_ptr) { /* not the same variable */
57 mpi_size_t i; /* copy the rest */
58 for (i = 0; i < s1_size - 1; i++)
59 res_ptr[i] = s1_ptr[i];
60 }
61 return 0; /* no carry */
62 }
63
64 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)65 mpihelp_add(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr, mpi_size_t s1_size,
66 mpi_ptr_t s2_ptr, mpi_size_t s2_size)
67 {
68 mpi_limb_t cy = 0;
69
70 if (s2_size)
71 cy = mpihelp_add_n(res_ptr, s1_ptr, s2_ptr, s2_size);
72
73 if (s1_size - s2_size)
74 cy = mpihelp_add_1(res_ptr + s2_size, s1_ptr + s2_size,
75 s1_size - s2_size, cy);
76 return cy;
77 }
78
79 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)80 mpihelp_sub_1(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr,
81 mpi_size_t s1_size, mpi_limb_t s2_limb)
82 {
83 mpi_limb_t x;
84
85 x = *s1_ptr++;
86 s2_limb = x - s2_limb;
87 *res_ptr++ = s2_limb;
88 if (s2_limb > x) {
89 while (--s1_size) {
90 x = *s1_ptr++;
91 *res_ptr++ = x - 1;
92 if (x)
93 goto leave;
94 }
95 return 1;
96 }
97
98 leave:
99 if (res_ptr != s1_ptr) {
100 mpi_size_t i;
101 for (i = 0; i < s1_size - 1; i++)
102 res_ptr[i] = s1_ptr[i];
103 }
104 return 0;
105 }
106
107 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)108 mpihelp_sub(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr, mpi_size_t s1_size,
109 mpi_ptr_t s2_ptr, mpi_size_t s2_size)
110 {
111 mpi_limb_t cy = 0;
112
113 if (s2_size)
114 cy = mpihelp_sub_n(res_ptr, s1_ptr, s2_ptr, s2_size);
115
116 if (s1_size - s2_size)
117 cy = mpihelp_sub_1(res_ptr + s2_size, s1_ptr + s2_size,
118 s1_size - s2_size, cy);
119 return cy;
120 }
121
122 #endif /*G10_MPI_INLINE_H */
123