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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 extern inline | |
34 | #endif | |
35 | ||
36 | G10_MPI_INLINE_DECL mpi_limb_t | |
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 | |
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 | |
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 | |
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 */ |