forked from mirrors/linux
6333cb31a7
Sync find_first_bit() and find_next_bit() implementation with the mother kernel. Also, drop unused find_last_bit() and find_next_clump8(). Signed-off-by: Yury Norov <yury.norov@gmail.com>
123 lines
3.4 KiB
C
123 lines
3.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* bit search implementation
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*
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* Copied from lib/find_bit.c to tools/lib/find_bit.c
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*
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* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* Copyright (C) 2008 IBM Corporation
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* 'find_last_bit' is written by Rusty Russell <rusty@rustcorp.com.au>
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* (Inspired by David Howell's find_next_bit implementation)
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*
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* Rewritten by Yury Norov <yury.norov@gmail.com> to decrease
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* size and improve performance, 2015.
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*/
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#include <linux/bitops.h>
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#include <linux/bitmap.h>
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#include <linux/kernel.h>
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/*
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* Common helper for find_bit() function family
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* @FETCH: The expression that fetches and pre-processes each word of bitmap(s)
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* @MUNGE: The expression that post-processes a word containing found bit (may be empty)
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* @size: The bitmap size in bits
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*/
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#define FIND_FIRST_BIT(FETCH, MUNGE, size) \
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({ \
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unsigned long idx, val, sz = (size); \
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\
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for (idx = 0; idx * BITS_PER_LONG < sz; idx++) { \
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val = (FETCH); \
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if (val) { \
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sz = min(idx * BITS_PER_LONG + __ffs(MUNGE(val)), sz); \
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break; \
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} \
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} \
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\
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sz; \
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})
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/*
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* Common helper for find_next_bit() function family
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* @FETCH: The expression that fetches and pre-processes each word of bitmap(s)
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* @MUNGE: The expression that post-processes a word containing found bit (may be empty)
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* @size: The bitmap size in bits
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* @start: The bitnumber to start searching at
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*/
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#define FIND_NEXT_BIT(FETCH, MUNGE, size, start) \
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({ \
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unsigned long mask, idx, tmp, sz = (size), __start = (start); \
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\
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if (unlikely(__start >= sz)) \
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goto out; \
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\
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mask = MUNGE(BITMAP_FIRST_WORD_MASK(__start)); \
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idx = __start / BITS_PER_LONG; \
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\
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for (tmp = (FETCH) & mask; !tmp; tmp = (FETCH)) { \
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if ((idx + 1) * BITS_PER_LONG >= sz) \
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goto out; \
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idx++; \
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} \
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\
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sz = min(idx * BITS_PER_LONG + __ffs(MUNGE(tmp)), sz); \
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out: \
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sz; \
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})
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#ifndef find_first_bit
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/*
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* Find the first set bit in a memory region.
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*/
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unsigned long _find_first_bit(const unsigned long *addr, unsigned long size)
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{
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return FIND_FIRST_BIT(addr[idx], /* nop */, size);
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}
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#endif
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#ifndef find_first_and_bit
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/*
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* Find the first set bit in two memory regions.
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*/
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unsigned long _find_first_and_bit(const unsigned long *addr1,
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const unsigned long *addr2,
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unsigned long size)
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{
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return FIND_FIRST_BIT(addr1[idx] & addr2[idx], /* nop */, size);
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}
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#endif
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#ifndef find_first_zero_bit
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/*
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* Find the first cleared bit in a memory region.
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*/
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unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size)
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{
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return FIND_FIRST_BIT(~addr[idx], /* nop */, size);
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}
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#endif
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#ifndef find_next_bit
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unsigned long _find_next_bit(const unsigned long *addr, unsigned long nbits, unsigned long start)
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{
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return FIND_NEXT_BIT(addr[idx], /* nop */, nbits, start);
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}
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#endif
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#ifndef find_next_and_bit
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unsigned long _find_next_and_bit(const unsigned long *addr1, const unsigned long *addr2,
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unsigned long nbits, unsigned long start)
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{
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return FIND_NEXT_BIT(addr1[idx] & addr2[idx], /* nop */, nbits, start);
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}
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#endif
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#ifndef find_next_zero_bit
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unsigned long _find_next_zero_bit(const unsigned long *addr, unsigned long nbits,
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unsigned long start)
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{
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return FIND_NEXT_BIT(~addr[idx], /* nop */, nbits, start);
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}
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#endif
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