Commit | Line | Data |
---|---|---|
b39fadb6 MW |
1 | /* -*-c-*- |
2 | * | |
3 | * Common definitions for OCB and related modes | |
4 | * | |
5 | * (c) 2018 Straylight/Edgeware | |
6 | */ | |
7 | ||
8 | /*----- Licensing notice --------------------------------------------------* | |
9 | * | |
10 | * This file is part of Catacomb. | |
11 | * | |
12 | * Catacomb is free software: you can redistribute it and/or modify it | |
13 | * under the terms of the GNU Library General Public License as published | |
14 | * by the Free Software Foundation; either version 2 of the License, or | |
15 | * (at your option) any later version. | |
16 | * | |
17 | * Catacomb is distributed in the hope that it will be useful, but | |
18 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
20 | * Library General Public License for more details. | |
21 | * | |
22 | * You should have received a copy of the GNU Library General Public | |
23 | * License along with Catacomb. If not, write to the Free Software | |
24 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, | |
25 | * USA. | |
26 | */ | |
27 | ||
28 | /*----- Header files ------------------------------------------------------*/ | |
29 | ||
30 | #include "config.h" | |
31 | ||
32 | #include "ocb.h" | |
33 | ||
34 | /*----- Main code ---------------------------------------------------------*/ | |
35 | ||
36 | /* --- @ocb_ctz@, @ocb_ctzl@ --- * | |
37 | * | |
38 | * Arguments: @unsigned i@ or @unsigned long i@ = operand, assumed nonzero | |
39 | * | |
40 | * Returns: The number of trailing zero bits in @i@, or nonsense if | |
41 | * %$i = 0$%. | |
42 | */ | |
43 | ||
44 | unsigned ocb_ctz(unsigned i) | |
45 | { | |
46 | unsigned n = 0; | |
47 | ||
48 | if (!(i&0x00ff)) { n += 8; i >>= 8; } | |
49 | if (!(i&0x000f)) { n += 4; i >>= 4; } | |
50 | if (!(i&0x0003)) { n += 2; i >>= 2; } | |
51 | if (!(i&0x0001)) { n += 1; i >>= 1; } | |
52 | return (n); | |
53 | } | |
54 | ||
55 | unsigned ocb_ctzl(unsigned long i) | |
56 | { | |
57 | unsigned n = 0; | |
58 | ||
59 | #if ULONG_BITS > 64 | |
60 | while (!(i&0xfffffffffffffffful)) { n += 64; i >>= 64; } | |
61 | #endif | |
62 | #if ULONG_BITS > 32 | |
63 | if (!(i&0xffffffff)) { n += 32; i >>= 32; } | |
64 | #endif | |
65 | if (!(i&0xffff)) { n += 16; i >>= 16; } | |
66 | if (!(i&0x00ff)) { n += 8; i >>= 8; } | |
67 | if (!(i&0x000f)) { n += 4; i >>= 4; } | |
68 | if (!(i&0x0003)) { n += 2; i >>= 2; } | |
69 | if (!(i&0x0001)) { n += 1; i >>= 1; } | |
70 | return (n); | |
71 | } | |
72 | ||
73 | /*----- That's all, folks -------------------------------------------------*/ |