util.h
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/*
* Copyright (C) 2014 Felix Fietkau <nbd@openwrt.org>
* Copyright (C) 2004 - 2009 Ivo van Doorn <IvDoorn@gmail.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#ifndef __MT76_UTIL_H
#define __MT76_UTIL_H
/*
* Power of two check, this will check
* if the mask that has been given contains and contiguous set of bits.
* Note that we cannot use the is_power_of_2() function since this
* check must be done at compile-time.
*/
#define is_power_of_two(x) ( !((x) & ((x)-1)) )
#define low_bit_mask(x) ( ((x)-1) & ~(x) )
#define is_valid_mask(x) is_power_of_two(1LU + (x) + low_bit_mask(x))
/*
* Macros to find first set bit in a variable.
* These macros behave the same as the __ffs() functions but
* the most important difference that this is done during
* compile-time rather then run-time.
*/
#define compile_ffs2(__x) \
__builtin_choose_expr(((__x) & 0x1), 0, 1)
#define compile_ffs4(__x) \
__builtin_choose_expr(((__x) & 0x3), \
(compile_ffs2((__x))), \
(compile_ffs2((__x) >> 2) + 2))
#define compile_ffs8(__x) \
__builtin_choose_expr(((__x) & 0xf), \
(compile_ffs4((__x))), \
(compile_ffs4((__x) >> 4) + 4))
#define compile_ffs16(__x) \
__builtin_choose_expr(((__x) & 0xff), \
(compile_ffs8((__x))), \
(compile_ffs8((__x) >> 8) + 8))
#define compile_ffs32(__x) \
__builtin_choose_expr(((__x) & 0xffff), \
(compile_ffs16((__x))), \
(compile_ffs16((__x) >> 16) + 16))
/*
* This macro will check the requirements for the FIELD{8,16,32} macros
* The mask should be a constant non-zero contiguous set of bits which
* does not exceed the given typelimit.
*/
#define FIELD_CHECK(__mask) \
BUILD_BUG_ON(!(__mask) || !is_valid_mask(__mask))
#define MT76_SET(_mask, _val) \
({ \
FIELD_CHECK(_mask); \
(((u32) (_val)) << compile_ffs32(_mask)) & _mask; \
})
#define MT76_GET(_mask, _val) \
({ \
FIELD_CHECK(_mask); \
(u32) (((_val) & _mask) >> compile_ffs32(_mask)); \
})
#endif