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e79864f316
Over the past couple years, the function _find_next_bit() was extended with parameters that modify its behavior to implement and- zero- and le- flavors. The parameters are passed at compile time, but current design prevents a compiler from optimizing out the conditionals. As find_next_bit() API grows, I expect that more parameters will be added. Current design would require more conditional code in _find_next_bit(), which would bloat the helper even more and make it barely readable. This patch replaces _find_next_bit() with a macro FIND_NEXT_BIT, and adds a set of wrappers, so that the compile-time optimizations become possible. The common logic is moved to the new macro, and all flavors may be generated by providing a FETCH macro parameter, like in this example: #define FIND_NEXT_BIT(FETCH, MUNGE, size, start) ... find_next_xornot_and_bit(addr1, addr2, addr3, size, start) { return FIND_NEXT_BIT(addr1[idx] ^ ~addr2[idx] & addr3[idx], /* nop */, size, start); } The FETCH may be of any complexity, as soon as it only refers the bitmap(s) and an iterator idx. MUNGE is here to support _le code generation for BE builds. May be empty. I ran find_bit_benchmark 16 times on top of 6.0-rc2 and 16 times on top of 6.0-rc2 + this series. The results for kvm/x86_64 are: v6.0-rc2 Optimized Difference Z-score Random dense bitmap ns ns ns % find_next_bit: 787735 670546 117189 14.9 3.97 find_next_zero_bit: 777492 664208 113284 14.6 10.51 find_last_bit: 830925 687573 143352 17.3 2.35 find_first_bit: 3874366 3306635 567731 14.7 1.84 find_first_and_bit: 40677125 37739887 2937238 7.2 1.36 find_next_and_bit: 347865 304456 43409 12.5 1.35 Random sparse bitmap find_next_bit: 19816 14021 5795 29.2 6.10 find_next_zero_bit: 1318901 1223794 95107 7.2 1.41 find_last_bit: 14573 13514 1059 7.3 6.92 find_first_bit: 1313321 1249024 64297 4.9 1.53 find_first_and_bit: 8921 8098 823 9.2 4.56 find_next_and_bit: 9796 7176 2620 26.7 5.39 Where the statistics is significant (z-score > 3), the improvement is ~15%. According to the bloat-o-meter, the Image size is 10-11K less: x86_64/defconfig: add/remove: 32/14 grow/shrink: 61/782 up/down: 6344/-16521 (-10177) arm64/defconfig: add/remove: 3/2 grow/shrink: 50/714 up/down: 608/-11556 (-10948) Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Yury Norov <yury.norov@gmail.com>
392 lines
12 KiB
C
392 lines
12 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __LINUX_FIND_H_
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#define __LINUX_FIND_H_
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#ifndef __LINUX_BITMAP_H
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#error only <linux/bitmap.h> can be included directly
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#endif
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#include <linux/bitops.h>
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unsigned long _find_next_bit(const unsigned long *addr1, unsigned long nbits,
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unsigned long start);
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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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unsigned long _find_next_zero_bit(const unsigned long *addr, unsigned long nbits,
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unsigned long start);
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extern unsigned long _find_first_bit(const unsigned long *addr, unsigned long size);
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extern unsigned long _find_first_and_bit(const unsigned long *addr1,
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const unsigned long *addr2, unsigned long size);
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extern unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size);
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extern unsigned long _find_last_bit(const unsigned long *addr, unsigned long size);
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#ifdef __BIG_ENDIAN
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unsigned long _find_first_zero_bit_le(const unsigned long *addr, unsigned long size);
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unsigned long _find_next_zero_bit_le(const unsigned long *addr, unsigned
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long size, unsigned long offset);
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unsigned long _find_next_bit_le(const unsigned long *addr, unsigned
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long size, unsigned long offset);
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#endif
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#ifndef find_next_bit
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/**
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* find_next_bit - find the next set bit in a memory region
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* @addr: The address to base the search on
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* @size: The bitmap size in bits
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* @offset: The bitnumber to start searching at
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*
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* Returns the bit number for the next set bit
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* If no bits are set, returns @size.
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*/
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static inline
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unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
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unsigned long offset)
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{
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if (small_const_nbits(size)) {
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unsigned long val;
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if (unlikely(offset >= size))
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return size;
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val = *addr & GENMASK(size - 1, offset);
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return val ? __ffs(val) : size;
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}
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return _find_next_bit(addr, size, offset);
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}
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#endif
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#ifndef find_next_and_bit
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/**
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* find_next_and_bit - find the next set bit in both memory regions
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* @addr1: The first address to base the search on
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* @addr2: The second address to base the search on
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* @size: The bitmap size in bits
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* @offset: The bitnumber to start searching at
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*
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* Returns the bit number for the next set bit
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* If no bits are set, returns @size.
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*/
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static inline
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unsigned long find_next_and_bit(const unsigned long *addr1,
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const unsigned long *addr2, unsigned long size,
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unsigned long offset)
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{
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if (small_const_nbits(size)) {
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unsigned long val;
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if (unlikely(offset >= size))
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return size;
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val = *addr1 & *addr2 & GENMASK(size - 1, offset);
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return val ? __ffs(val) : size;
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}
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return _find_next_and_bit(addr1, addr2, size, offset);
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}
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#endif
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#ifndef find_next_zero_bit
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/**
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* find_next_zero_bit - find the next cleared bit in a memory region
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* @addr: The address to base the search on
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* @size: The bitmap size in bits
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* @offset: The bitnumber to start searching at
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*
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* Returns the bit number of the next zero bit
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* If no bits are zero, returns @size.
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*/
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static inline
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unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
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unsigned long offset)
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{
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if (small_const_nbits(size)) {
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unsigned long val;
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if (unlikely(offset >= size))
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return size;
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val = *addr | ~GENMASK(size - 1, offset);
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return val == ~0UL ? size : ffz(val);
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}
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return _find_next_zero_bit(addr, size, offset);
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}
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#endif
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#ifndef find_first_bit
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/**
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* find_first_bit - find the first set bit in a memory region
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* @addr: The address to start the search at
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* @size: The maximum number of bits to search
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*
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* Returns the bit number of the first set bit.
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* If no bits are set, returns @size.
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*/
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static inline
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unsigned long find_first_bit(const unsigned long *addr, unsigned long size)
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{
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if (small_const_nbits(size)) {
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unsigned long val = *addr & GENMASK(size - 1, 0);
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return val ? __ffs(val) : size;
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}
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return _find_first_bit(addr, 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_first_and_bit - find the first set bit in both memory regions
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* @addr1: The first address to base the search on
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* @addr2: The second address to base the search on
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* @size: The bitmap size in bits
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*
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* Returns the bit number for the next set bit
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* If no bits are set, returns @size.
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*/
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static inline
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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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if (small_const_nbits(size)) {
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unsigned long val = *addr1 & *addr2 & GENMASK(size - 1, 0);
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return val ? __ffs(val) : size;
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}
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return _find_first_and_bit(addr1, addr2, 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_first_zero_bit - find the first cleared bit in a memory region
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* @addr: The address to start the search at
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* @size: The maximum number of bits to search
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*
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* Returns the bit number of the first cleared bit.
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* If no bits are zero, returns @size.
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*/
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static inline
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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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if (small_const_nbits(size)) {
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unsigned long val = *addr | ~GENMASK(size - 1, 0);
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return val == ~0UL ? size : ffz(val);
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}
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return _find_first_zero_bit(addr, size);
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}
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#endif
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#ifndef find_last_bit
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/**
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* find_last_bit - find the last set bit in a memory region
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* @addr: The address to start the search at
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* @size: The number of bits to search
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*
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* Returns the bit number of the last set bit, or size.
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*/
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static inline
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unsigned long find_last_bit(const unsigned long *addr, unsigned long size)
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{
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if (small_const_nbits(size)) {
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unsigned long val = *addr & GENMASK(size - 1, 0);
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return val ? __fls(val) : size;
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}
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return _find_last_bit(addr, size);
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}
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#endif
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/**
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* find_next_clump8 - find next 8-bit clump with set bits in a memory region
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* @clump: location to store copy of found clump
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* @addr: address to base the search on
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* @size: bitmap size in number of bits
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* @offset: bit offset at which to start searching
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*
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* Returns the bit offset for the next set clump; the found clump value is
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* copied to the location pointed by @clump. If no bits are set, returns @size.
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*/
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extern unsigned long find_next_clump8(unsigned long *clump,
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const unsigned long *addr,
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unsigned long size, unsigned long offset);
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#define find_first_clump8(clump, bits, size) \
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find_next_clump8((clump), (bits), (size), 0)
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#if defined(__LITTLE_ENDIAN)
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static inline unsigned long find_next_zero_bit_le(const void *addr,
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unsigned long size, unsigned long offset)
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{
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return find_next_zero_bit(addr, size, offset);
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}
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static inline unsigned long find_next_bit_le(const void *addr,
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unsigned long size, unsigned long offset)
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{
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return find_next_bit(addr, size, offset);
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}
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static inline unsigned long find_first_zero_bit_le(const void *addr,
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unsigned long size)
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{
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return find_first_zero_bit(addr, size);
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}
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#elif defined(__BIG_ENDIAN)
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#ifndef find_next_zero_bit_le
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static inline
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unsigned long find_next_zero_bit_le(const void *addr, unsigned
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long size, unsigned long offset)
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{
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if (small_const_nbits(size)) {
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unsigned long val = *(const unsigned long *)addr;
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if (unlikely(offset >= size))
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return size;
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val = swab(val) | ~GENMASK(size - 1, offset);
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return val == ~0UL ? size : ffz(val);
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}
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return _find_next_zero_bit_le(addr, size, offset);
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}
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#endif
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#ifndef find_first_zero_bit_le
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static inline
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unsigned long find_first_zero_bit_le(const void *addr, unsigned long size)
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{
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if (small_const_nbits(size)) {
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unsigned long val = swab(*(const unsigned long *)addr) | ~GENMASK(size - 1, 0);
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return val == ~0UL ? size : ffz(val);
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}
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return _find_first_zero_bit_le(addr, size);
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}
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#endif
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#ifndef find_next_bit_le
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static inline
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unsigned long find_next_bit_le(const void *addr, unsigned
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long size, unsigned long offset)
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{
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if (small_const_nbits(size)) {
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unsigned long val = *(const unsigned long *)addr;
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if (unlikely(offset >= size))
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return size;
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val = swab(val) & GENMASK(size - 1, offset);
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return val ? __ffs(val) : size;
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}
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return _find_next_bit_le(addr, size, offset);
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}
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#endif
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#else
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#error "Please fix <asm/byteorder.h>"
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#endif
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#define for_each_set_bit(bit, addr, size) \
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for ((bit) = find_next_bit((addr), (size), 0); \
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(bit) < (size); \
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(bit) = find_next_bit((addr), (size), (bit) + 1))
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/* same as for_each_set_bit() but use bit as value to start with */
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#define for_each_set_bit_from(bit, addr, size) \
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for ((bit) = find_next_bit((addr), (size), (bit)); \
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(bit) < (size); \
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(bit) = find_next_bit((addr), (size), (bit) + 1))
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#define for_each_clear_bit(bit, addr, size) \
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for ((bit) = find_next_zero_bit((addr), (size), 0); \
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(bit) < (size); \
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(bit) = find_next_zero_bit((addr), (size), (bit) + 1))
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/* same as for_each_clear_bit() but use bit as value to start with */
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#define for_each_clear_bit_from(bit, addr, size) \
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for ((bit) = find_next_zero_bit((addr), (size), (bit)); \
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(bit) < (size); \
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(bit) = find_next_zero_bit((addr), (size), (bit) + 1))
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/**
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* for_each_set_bitrange - iterate over all set bit ranges [b; e)
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* @b: bit offset of start of current bitrange (first set bit)
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* @e: bit offset of end of current bitrange (first unset bit)
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* @addr: bitmap address to base the search on
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* @size: bitmap size in number of bits
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*/
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#define for_each_set_bitrange(b, e, addr, size) \
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for ((b) = find_next_bit((addr), (size), 0), \
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(e) = find_next_zero_bit((addr), (size), (b) + 1); \
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(b) < (size); \
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(b) = find_next_bit((addr), (size), (e) + 1), \
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(e) = find_next_zero_bit((addr), (size), (b) + 1))
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/**
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* for_each_set_bitrange_from - iterate over all set bit ranges [b; e)
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* @b: bit offset of start of current bitrange (first set bit); must be initialized
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* @e: bit offset of end of current bitrange (first unset bit)
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* @addr: bitmap address to base the search on
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* @size: bitmap size in number of bits
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*/
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#define for_each_set_bitrange_from(b, e, addr, size) \
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for ((b) = find_next_bit((addr), (size), (b)), \
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(e) = find_next_zero_bit((addr), (size), (b) + 1); \
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(b) < (size); \
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(b) = find_next_bit((addr), (size), (e) + 1), \
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(e) = find_next_zero_bit((addr), (size), (b) + 1))
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/**
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* for_each_clear_bitrange - iterate over all unset bit ranges [b; e)
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* @b: bit offset of start of current bitrange (first unset bit)
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* @e: bit offset of end of current bitrange (first set bit)
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* @addr: bitmap address to base the search on
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* @size: bitmap size in number of bits
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*/
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#define for_each_clear_bitrange(b, e, addr, size) \
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for ((b) = find_next_zero_bit((addr), (size), 0), \
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(e) = find_next_bit((addr), (size), (b) + 1); \
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(b) < (size); \
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(b) = find_next_zero_bit((addr), (size), (e) + 1), \
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(e) = find_next_bit((addr), (size), (b) + 1))
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/**
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* for_each_clear_bitrange_from - iterate over all unset bit ranges [b; e)
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* @b: bit offset of start of current bitrange (first set bit); must be initialized
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* @e: bit offset of end of current bitrange (first unset bit)
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* @addr: bitmap address to base the search on
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* @size: bitmap size in number of bits
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*/
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#define for_each_clear_bitrange_from(b, e, addr, size) \
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for ((b) = find_next_zero_bit((addr), (size), (b)), \
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(e) = find_next_bit((addr), (size), (b) + 1); \
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(b) < (size); \
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(b) = find_next_zero_bit((addr), (size), (e) + 1), \
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(e) = find_next_bit((addr), (size), (b) + 1))
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/**
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* for_each_set_clump8 - iterate over bitmap for each 8-bit clump with set bits
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* @start: bit offset to start search and to store the current iteration offset
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* @clump: location to store copy of current 8-bit clump
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* @bits: bitmap address to base the search on
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* @size: bitmap size in number of bits
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*/
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#define for_each_set_clump8(start, clump, bits, size) \
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for ((start) = find_first_clump8(&(clump), (bits), (size)); \
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(start) < (size); \
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(start) = find_next_clump8(&(clump), (bits), (size), (start) + 8))
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#endif /*__LINUX_FIND_H_ */
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