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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 */ |
123 |
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