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