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 3 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, see <http://www.gnu.org/licenses/>.
18 *
19 * Note: This code is heavily based on the GNU MP Library.
20 * Actually it's the same code with only minor changes in the
21 * way the data is stored; this is to support the abstraction
22 * of an optional secure memory allocation which may be used
23 * to avoid revealing of sensitive data due to paging etc.
24 * The GNU MP Library itself is published under the LGPL;
25 * however I decided to publish this code under the plain GPL.
26 */
27
28 #ifndef G10_MPI_INLINE_H
29 #define G10_MPI_INLINE_H
30
31 /* Starting with gcc 4.3 "extern inline" conforms in c99 mode to the
32 c99 semantics. To keep the useful old semantics we use an
33 attribute. */
34 #ifndef G10_MPI_INLINE_DECL
35 # ifdef __GNUC_STDC_INLINE__
36 # define G10_MPI_INLINE_DECL extern inline __attribute__ ((__gnu_inline__))
37 # else
38 # define G10_MPI_INLINE_DECL extern __inline__
39 # endif
40 #endif
41
42 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)43 mpihelp_add_1( mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr,
44 mpi_size_t s1_size, mpi_limb_t s2_limb)
45 {
46 mpi_limb_t x;
47
48 x = *s1_ptr++;
49 s2_limb += x;
50 *res_ptr++ = s2_limb;
51 if( s2_limb < x ) { /* sum is less than the left operand: handle carry */
52 while( --s1_size ) {
53 x = *s1_ptr++ + 1; /* add carry */
54 *res_ptr++ = x; /* and store */
55 if( x ) /* not 0 (no overflow): we can stop */
56 goto leave;
57 }
58 return 1; /* return carry (size of s1 to small) */
59 }
60
61 leave:
62 if( res_ptr != s1_ptr ) { /* not the same variable */
63 mpi_size_t i; /* copy the rest */
64 for( i=0; i < s1_size-1; i++ )
65 res_ptr[i] = s1_ptr[i];
66 }
67 return 0; /* no carry */
68 }
69
70
71
72 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)73 mpihelp_add(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr, mpi_size_t s1_size,
74 mpi_ptr_t s2_ptr, mpi_size_t s2_size)
75 {
76 mpi_limb_t cy = 0;
77
78 if( s2_size )
79 cy = mpihelp_add_n( res_ptr, s1_ptr, s2_ptr, s2_size );
80
81 if( s1_size - s2_size )
82 cy = mpihelp_add_1( res_ptr + s2_size, s1_ptr + s2_size,
83 s1_size - s2_size, cy);
84 return cy;
85 }
86
87
88 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)89 mpihelp_sub_1(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr,
90 mpi_size_t s1_size, mpi_limb_t s2_limb )
91 {
92 mpi_limb_t x;
93
94 x = *s1_ptr++;
95 s2_limb = x - s2_limb;
96 *res_ptr++ = s2_limb;
97 if( s2_limb > x ) {
98 while( --s1_size ) {
99 x = *s1_ptr++;
100 *res_ptr++ = x - 1;
101 if( x )
102 goto leave;
103 }
104 return 1;
105 }
106
107 leave:
108 if( res_ptr != s1_ptr ) {
109 mpi_size_t i;
110 for( i=0; i < s1_size-1; i++ )
111 res_ptr[i] = s1_ptr[i];
112 }
113 return 0;
114 }
115
116
117
118 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)119 mpihelp_sub( mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr, mpi_size_t s1_size,
120 mpi_ptr_t s2_ptr, mpi_size_t s2_size)
121 {
122 mpi_limb_t cy = 0;
123
124 if( s2_size )
125 cy = mpihelp_sub_n(res_ptr, s1_ptr, s2_ptr, s2_size);
126
127 if( s1_size - s2_size )
128 cy = mpihelp_sub_1(res_ptr + s2_size, s1_ptr + s2_size,
129 s1_size - s2_size, cy);
130 return cy;
131 }
132
133 #endif /*G10_MPI_INLINE_H*/
134