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465ae836 | 1 | /* SPDX-License-Identifier: GPL-2.0-or-later */ |
5ce3e312 DK |
2 | /* mpi-inline.h - Internal to the Multi Precision Integers |
3 | * Copyright (C) 1994, 1996, 1998, 1999 Free Software Foundation, Inc. | |
4 | * | |
5 | * This file is part of GnuPG. | |
6 | * | |
5ce3e312 DK |
7 | * Note: This code is heavily based on the GNU MP Library. |
8 | * Actually it's the same code with only minor changes in the | |
9 | * way the data is stored; this is to support the abstraction | |
10 | * of an optional secure memory allocation which may be used | |
11 | * to avoid revealing of sensitive data due to paging etc. | |
12 | * The GNU MP Library itself is published under the LGPL; | |
13 | * however I decided to publish this code under the plain GPL. | |
14 | */ | |
15 | ||
16 | #ifndef G10_MPI_INLINE_H | |
17 | #define G10_MPI_INLINE_H | |
18 | ||
19 | #ifndef G10_MPI_INLINE_DECL | |
9c6bd0c2 | 20 | #define G10_MPI_INLINE_DECL static inline |
5ce3e312 DK |
21 | #endif |
22 | ||
23 | G10_MPI_INLINE_DECL mpi_limb_t | |
24 | mpihelp_add_1(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr, | |
25 | mpi_size_t s1_size, mpi_limb_t s2_limb) | |
26 | { | |
27 | mpi_limb_t x; | |
28 | ||
29 | x = *s1_ptr++; | |
30 | s2_limb += x; | |
31 | *res_ptr++ = s2_limb; | |
32 | if (s2_limb < x) { /* sum is less than the left operand: handle carry */ | |
33 | while (--s1_size) { | |
34 | x = *s1_ptr++ + 1; /* add carry */ | |
35 | *res_ptr++ = x; /* and store */ | |
36 | if (x) /* not 0 (no overflow): we can stop */ | |
37 | goto leave; | |
38 | } | |
39 | return 1; /* return carry (size of s1 to small) */ | |
40 | } | |
41 | ||
42 | leave: | |
43 | if (res_ptr != s1_ptr) { /* not the same variable */ | |
44 | mpi_size_t i; /* copy the rest */ | |
45 | for (i = 0; i < s1_size - 1; i++) | |
46 | res_ptr[i] = s1_ptr[i]; | |
47 | } | |
48 | return 0; /* no carry */ | |
49 | } | |
50 | ||
51 | G10_MPI_INLINE_DECL mpi_limb_t | |
52 | mpihelp_add(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr, mpi_size_t s1_size, | |
53 | mpi_ptr_t s2_ptr, mpi_size_t s2_size) | |
54 | { | |
55 | mpi_limb_t cy = 0; | |
56 | ||
57 | if (s2_size) | |
58 | cy = mpihelp_add_n(res_ptr, s1_ptr, s2_ptr, s2_size); | |
59 | ||
60 | if (s1_size - s2_size) | |
61 | cy = mpihelp_add_1(res_ptr + s2_size, s1_ptr + s2_size, | |
62 | s1_size - s2_size, cy); | |
63 | return cy; | |
64 | } | |
65 | ||
66 | G10_MPI_INLINE_DECL mpi_limb_t | |
67 | mpihelp_sub_1(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr, | |
68 | mpi_size_t s1_size, mpi_limb_t s2_limb) | |
69 | { | |
70 | mpi_limb_t x; | |
71 | ||
72 | x = *s1_ptr++; | |
73 | s2_limb = x - s2_limb; | |
74 | *res_ptr++ = s2_limb; | |
75 | if (s2_limb > x) { | |
76 | while (--s1_size) { | |
77 | x = *s1_ptr++; | |
78 | *res_ptr++ = x - 1; | |
79 | if (x) | |
80 | goto leave; | |
81 | } | |
82 | return 1; | |
83 | } | |
84 | ||
85 | leave: | |
86 | if (res_ptr != s1_ptr) { | |
87 | mpi_size_t i; | |
88 | for (i = 0; i < s1_size - 1; i++) | |
89 | res_ptr[i] = s1_ptr[i]; | |
90 | } | |
91 | return 0; | |
92 | } | |
93 | ||
94 | G10_MPI_INLINE_DECL mpi_limb_t | |
95 | mpihelp_sub(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr, mpi_size_t s1_size, | |
96 | mpi_ptr_t s2_ptr, mpi_size_t s2_size) | |
97 | { | |
98 | mpi_limb_t cy = 0; | |
99 | ||
100 | if (s2_size) | |
101 | cy = mpihelp_sub_n(res_ptr, s1_ptr, s2_ptr, s2_size); | |
102 | ||
103 | if (s1_size - s2_size) | |
104 | cy = mpihelp_sub_1(res_ptr + s2_size, s1_ptr + s2_size, | |
105 | s1_size - s2_size, cy); | |
106 | return cy; | |
107 | } | |
108 | ||
109 | #endif /*G10_MPI_INLINE_H */ |