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c869f77d JK |
1 | /* |
2 | * Copyright (C) 2014 Felix Fietkau <nbd@openwrt.org> | |
3 | * Copyright (C) 2004 - 2009 Ivo van Doorn <IvDoorn@gmail.com> | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify | |
6 | * it under the terms of the GNU General Public License version 2 | |
7 | * as published by the Free Software Foundation | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | * GNU General Public License for more details. | |
13 | */ | |
14 | ||
15 | #ifndef __MT76_UTIL_H | |
16 | #define __MT76_UTIL_H | |
17 | ||
18 | /* | |
19 | * Power of two check, this will check | |
20 | * if the mask that has been given contains and contiguous set of bits. | |
21 | * Note that we cannot use the is_power_of_2() function since this | |
22 | * check must be done at compile-time. | |
23 | */ | |
24 | #define is_power_of_two(x) ( !((x) & ((x)-1)) ) | |
25 | #define low_bit_mask(x) ( ((x)-1) & ~(x) ) | |
26 | #define is_valid_mask(x) is_power_of_two(1LU + (x) + low_bit_mask(x)) | |
27 | ||
28 | /* | |
29 | * Macros to find first set bit in a variable. | |
30 | * These macros behave the same as the __ffs() functions but | |
31 | * the most important difference that this is done during | |
32 | * compile-time rather then run-time. | |
33 | */ | |
34 | #define compile_ffs2(__x) \ | |
35 | __builtin_choose_expr(((__x) & 0x1), 0, 1) | |
36 | ||
37 | #define compile_ffs4(__x) \ | |
38 | __builtin_choose_expr(((__x) & 0x3), \ | |
39 | (compile_ffs2((__x))), \ | |
40 | (compile_ffs2((__x) >> 2) + 2)) | |
41 | ||
42 | #define compile_ffs8(__x) \ | |
43 | __builtin_choose_expr(((__x) & 0xf), \ | |
44 | (compile_ffs4((__x))), \ | |
45 | (compile_ffs4((__x) >> 4) + 4)) | |
46 | ||
47 | #define compile_ffs16(__x) \ | |
48 | __builtin_choose_expr(((__x) & 0xff), \ | |
49 | (compile_ffs8((__x))), \ | |
50 | (compile_ffs8((__x) >> 8) + 8)) | |
51 | ||
52 | #define compile_ffs32(__x) \ | |
53 | __builtin_choose_expr(((__x) & 0xffff), \ | |
54 | (compile_ffs16((__x))), \ | |
55 | (compile_ffs16((__x) >> 16) + 16)) | |
56 | ||
57 | /* | |
58 | * This macro will check the requirements for the FIELD{8,16,32} macros | |
59 | * The mask should be a constant non-zero contiguous set of bits which | |
60 | * does not exceed the given typelimit. | |
61 | */ | |
62 | #define FIELD_CHECK(__mask) \ | |
63 | BUILD_BUG_ON(!(__mask) || !is_valid_mask(__mask)) | |
64 | ||
65 | #define MT76_SET(_mask, _val) \ | |
66 | ({ \ | |
67 | FIELD_CHECK(_mask); \ | |
68 | (((u32) (_val)) << compile_ffs32(_mask)) & _mask; \ | |
69 | }) | |
70 | ||
71 | #define MT76_GET(_mask, _val) \ | |
72 | ({ \ | |
73 | FIELD_CHECK(_mask); \ | |
74 | (u32) (((_val) & _mask) >> compile_ffs32(_mask)); \ | |
75 | }) | |
76 | ||
77 | #endif |