forked from mirrors/linux
409ca45526
Remove an unnecessary arch complication:
arch/x86/include/asm/arch_hweight.h uses __sw_hweight{32,64} as
alternatives, and they are implemented in arch/x86/lib/hweight.S
x86 does not rely on the generic C implementation lib/hweight.c
at all, so CONFIG_GENERIC_HWEIGHT should be disabled.
__HAVE_ARCH_SW_HWEIGHT is not necessary either.
No change in functionality intended.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Uros Bizjak <ubizjak@gmail.com>
Link: http://lkml.kernel.org/r/1557665521-17570-1-git-send-email-yamada.masahiro@socionext.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
68 lines
1.9 KiB
C
68 lines
1.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/export.h>
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#include <linux/bitops.h>
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#include <asm/types.h>
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/**
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* hweightN - returns the hamming weight of a N-bit word
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* @x: the word to weigh
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*
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* The Hamming Weight of a number is the total number of bits set in it.
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*/
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unsigned int __sw_hweight32(unsigned int w)
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{
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#ifdef CONFIG_ARCH_HAS_FAST_MULTIPLIER
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w -= (w >> 1) & 0x55555555;
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w = (w & 0x33333333) + ((w >> 2) & 0x33333333);
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w = (w + (w >> 4)) & 0x0f0f0f0f;
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return (w * 0x01010101) >> 24;
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#else
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unsigned int res = w - ((w >> 1) & 0x55555555);
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res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
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res = (res + (res >> 4)) & 0x0F0F0F0F;
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res = res + (res >> 8);
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return (res + (res >> 16)) & 0x000000FF;
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#endif
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}
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EXPORT_SYMBOL(__sw_hweight32);
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unsigned int __sw_hweight16(unsigned int w)
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{
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unsigned int res = w - ((w >> 1) & 0x5555);
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res = (res & 0x3333) + ((res >> 2) & 0x3333);
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res = (res + (res >> 4)) & 0x0F0F;
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return (res + (res >> 8)) & 0x00FF;
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}
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EXPORT_SYMBOL(__sw_hweight16);
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unsigned int __sw_hweight8(unsigned int w)
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{
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unsigned int res = w - ((w >> 1) & 0x55);
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res = (res & 0x33) + ((res >> 2) & 0x33);
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return (res + (res >> 4)) & 0x0F;
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}
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EXPORT_SYMBOL(__sw_hweight8);
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unsigned long __sw_hweight64(__u64 w)
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{
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#if BITS_PER_LONG == 32
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return __sw_hweight32((unsigned int)(w >> 32)) +
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__sw_hweight32((unsigned int)w);
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#elif BITS_PER_LONG == 64
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#ifdef CONFIG_ARCH_HAS_FAST_MULTIPLIER
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w -= (w >> 1) & 0x5555555555555555ul;
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w = (w & 0x3333333333333333ul) + ((w >> 2) & 0x3333333333333333ul);
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w = (w + (w >> 4)) & 0x0f0f0f0f0f0f0f0ful;
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return (w * 0x0101010101010101ul) >> 56;
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#else
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__u64 res = w - ((w >> 1) & 0x5555555555555555ul);
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res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul);
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res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0Ful;
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res = res + (res >> 8);
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res = res + (res >> 16);
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return (res + (res >> 32)) & 0x00000000000000FFul;
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#endif
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#endif
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}
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EXPORT_SYMBOL(__sw_hweight64);
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