diff options
Diffstat (limited to 'lib/mpi/mpi-bit.c')
-rw-r--r-- | lib/mpi/mpi-bit.c | 236 |
1 files changed, 236 insertions, 0 deletions
diff --git a/lib/mpi/mpi-bit.c b/lib/mpi/mpi-bit.c new file mode 100644 index 000000000000..854c9c6da025 --- /dev/null +++ b/lib/mpi/mpi-bit.c | |||
@@ -0,0 +1,236 @@ | |||
1 | /* mpi-bit.c - MPI bit level fucntions | ||
2 | * Copyright (C) 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 | |||
21 | #include "mpi-internal.h" | ||
22 | #include "longlong.h" | ||
23 | |||
24 | const unsigned char __clz_tab[] = { | ||
25 | 0, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, | ||
26 | 5, 5, 5, 5, 5, 5, 5, 5, | ||
27 | 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, | ||
28 | 6, 6, 6, 6, 6, 6, 6, 6, | ||
29 | 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, | ||
30 | 7, 7, 7, 7, 7, 7, 7, 7, | ||
31 | 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, | ||
32 | 7, 7, 7, 7, 7, 7, 7, 7, | ||
33 | 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, | ||
34 | 8, 8, 8, 8, 8, 8, 8, 8, | ||
35 | 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, | ||
36 | 8, 8, 8, 8, 8, 8, 8, 8, | ||
37 | 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, | ||
38 | 8, 8, 8, 8, 8, 8, 8, 8, | ||
39 | 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, | ||
40 | 8, 8, 8, 8, 8, 8, 8, 8, | ||
41 | }; | ||
42 | |||
43 | #define A_LIMB_1 ((mpi_limb_t) 1) | ||
44 | |||
45 | /**************** | ||
46 | * Sometimes we have MSL (most significant limbs) which are 0; | ||
47 | * this is for some reasons not good, so this function removes them. | ||
48 | */ | ||
49 | void mpi_normalize(MPI a) | ||
50 | { | ||
51 | for (; a->nlimbs && !a->d[a->nlimbs - 1]; a->nlimbs--) | ||
52 | ; | ||
53 | } | ||
54 | |||
55 | /**************** | ||
56 | * Return the number of bits in A. | ||
57 | */ | ||
58 | unsigned mpi_get_nbits(MPI a) | ||
59 | { | ||
60 | unsigned n; | ||
61 | |||
62 | mpi_normalize(a); | ||
63 | |||
64 | if (a->nlimbs) { | ||
65 | mpi_limb_t alimb = a->d[a->nlimbs - 1]; | ||
66 | if (alimb) | ||
67 | count_leading_zeros(n, alimb); | ||
68 | else | ||
69 | n = BITS_PER_MPI_LIMB; | ||
70 | n = BITS_PER_MPI_LIMB - n + (a->nlimbs - 1) * BITS_PER_MPI_LIMB; | ||
71 | } else | ||
72 | n = 0; | ||
73 | return n; | ||
74 | } | ||
75 | EXPORT_SYMBOL_GPL(mpi_get_nbits); | ||
76 | |||
77 | /**************** | ||
78 | * Test whether bit N is set. | ||
79 | */ | ||
80 | int mpi_test_bit(MPI a, unsigned n) | ||
81 | { | ||
82 | unsigned limbno, bitno; | ||
83 | mpi_limb_t limb; | ||
84 | |||
85 | limbno = n / BITS_PER_MPI_LIMB; | ||
86 | bitno = n % BITS_PER_MPI_LIMB; | ||
87 | |||
88 | if (limbno >= a->nlimbs) | ||
89 | return 0; /* too far left: this is a 0 */ | ||
90 | limb = a->d[limbno]; | ||
91 | return (limb & (A_LIMB_1 << bitno)) ? 1 : 0; | ||
92 | } | ||
93 | |||
94 | /**************** | ||
95 | * Set bit N of A. | ||
96 | */ | ||
97 | int mpi_set_bit(MPI a, unsigned n) | ||
98 | { | ||
99 | unsigned limbno, bitno; | ||
100 | |||
101 | limbno = n / BITS_PER_MPI_LIMB; | ||
102 | bitno = n % BITS_PER_MPI_LIMB; | ||
103 | |||
104 | if (limbno >= a->nlimbs) { /* resize */ | ||
105 | if (a->alloced >= limbno) | ||
106 | if (mpi_resize(a, limbno + 1) < 0) | ||
107 | return -ENOMEM; | ||
108 | a->nlimbs = limbno + 1; | ||
109 | } | ||
110 | a->d[limbno] |= (A_LIMB_1 << bitno); | ||
111 | return 0; | ||
112 | } | ||
113 | |||
114 | /**************** | ||
115 | * Set bit N of A. and clear all bits above | ||
116 | */ | ||
117 | int mpi_set_highbit(MPI a, unsigned n) | ||
118 | { | ||
119 | unsigned limbno, bitno; | ||
120 | |||
121 | limbno = n / BITS_PER_MPI_LIMB; | ||
122 | bitno = n % BITS_PER_MPI_LIMB; | ||
123 | |||
124 | if (limbno >= a->nlimbs) { /* resize */ | ||
125 | if (a->alloced >= limbno) | ||
126 | if (mpi_resize(a, limbno + 1) < 0) | ||
127 | return -ENOMEM; | ||
128 | a->nlimbs = limbno + 1; | ||
129 | } | ||
130 | a->d[limbno] |= (A_LIMB_1 << bitno); | ||
131 | for (bitno++; bitno < BITS_PER_MPI_LIMB; bitno++) | ||
132 | a->d[limbno] &= ~(A_LIMB_1 << bitno); | ||
133 | a->nlimbs = limbno + 1; | ||
134 | return 0; | ||
135 | } | ||
136 | |||
137 | /**************** | ||
138 | * clear bit N of A and all bits above | ||
139 | */ | ||
140 | void mpi_clear_highbit(MPI a, unsigned n) | ||
141 | { | ||
142 | unsigned limbno, bitno; | ||
143 | |||
144 | limbno = n / BITS_PER_MPI_LIMB; | ||
145 | bitno = n % BITS_PER_MPI_LIMB; | ||
146 | |||
147 | if (limbno >= a->nlimbs) | ||
148 | return; /* not allocated, so need to clear bits :-) */ | ||
149 | |||
150 | for (; bitno < BITS_PER_MPI_LIMB; bitno++) | ||
151 | a->d[limbno] &= ~(A_LIMB_1 << bitno); | ||
152 | a->nlimbs = limbno + 1; | ||
153 | } | ||
154 | |||
155 | /**************** | ||
156 | * Clear bit N of A. | ||
157 | */ | ||
158 | void mpi_clear_bit(MPI a, unsigned n) | ||
159 | { | ||
160 | unsigned limbno, bitno; | ||
161 | |||
162 | limbno = n / BITS_PER_MPI_LIMB; | ||
163 | bitno = n % BITS_PER_MPI_LIMB; | ||
164 | |||
165 | if (limbno >= a->nlimbs) | ||
166 | return; /* don't need to clear this bit, it's to far to left */ | ||
167 | a->d[limbno] &= ~(A_LIMB_1 << bitno); | ||
168 | } | ||
169 | |||
170 | /**************** | ||
171 | * Shift A by N bits to the right | ||
172 | * FIXME: should use alloc_limb if X and A are same. | ||
173 | */ | ||
174 | int mpi_rshift(MPI x, MPI a, unsigned n) | ||
175 | { | ||
176 | mpi_ptr_t xp; | ||
177 | mpi_size_t xsize; | ||
178 | |||
179 | xsize = a->nlimbs; | ||
180 | x->sign = a->sign; | ||
181 | if (RESIZE_IF_NEEDED(x, (size_t) xsize) < 0) | ||
182 | return -ENOMEM; | ||
183 | xp = x->d; | ||
184 | |||
185 | if (xsize) { | ||
186 | mpihelp_rshift(xp, a->d, xsize, n); | ||
187 | MPN_NORMALIZE(xp, xsize); | ||
188 | } | ||
189 | x->nlimbs = xsize; | ||
190 | return 0; | ||
191 | } | ||
192 | |||
193 | /**************** | ||
194 | * Shift A by COUNT limbs to the left | ||
195 | * This is used only within the MPI library | ||
196 | */ | ||
197 | int mpi_lshift_limbs(MPI a, unsigned int count) | ||
198 | { | ||
199 | mpi_ptr_t ap = a->d; | ||
200 | int n = a->nlimbs; | ||
201 | int i; | ||
202 | |||
203 | if (!count || !n) | ||
204 | return 0; | ||
205 | |||
206 | if (RESIZE_IF_NEEDED(a, n + count) < 0) | ||
207 | return -ENOMEM; | ||
208 | |||
209 | for (i = n - 1; i >= 0; i--) | ||
210 | ap[i + count] = ap[i]; | ||
211 | for (i = 0; i < count; i++) | ||
212 | ap[i] = 0; | ||
213 | a->nlimbs += count; | ||
214 | return 0; | ||
215 | } | ||
216 | |||
217 | /**************** | ||
218 | * Shift A by COUNT limbs to the right | ||
219 | * This is used only within the MPI library | ||
220 | */ | ||
221 | void mpi_rshift_limbs(MPI a, unsigned int count) | ||
222 | { | ||
223 | mpi_ptr_t ap = a->d; | ||
224 | mpi_size_t n = a->nlimbs; | ||
225 | unsigned int i; | ||
226 | |||
227 | if (count >= n) { | ||
228 | a->nlimbs = 0; | ||
229 | return; | ||
230 | } | ||
231 | |||
232 | for (i = 0; i < n - count; i++) | ||
233 | ap[i] = ap[i + count]; | ||
234 | ap[i] = 0; | ||
235 | a->nlimbs -= count; | ||
236 | } | ||