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3a48305028
Avoid a call to find_first_bit if the bitmap size is know at compile time and small enough to fit in a single long integer. Modeled after an optimization in the original x86_64-specific code. Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm> Signed-off-by: Ingo Molnar <mingo@elte.hu>
256 lines
6.8 KiB
C
256 lines
6.8 KiB
C
#ifndef _LINUX_BITOPS_H
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#define _LINUX_BITOPS_H
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#include <asm/types.h>
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#ifdef __KERNEL__
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#define BIT(nr) (1UL << (nr))
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#define BIT_MASK(nr) (1UL << ((nr) % BITS_PER_LONG))
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#define BIT_WORD(nr) ((nr) / BITS_PER_LONG)
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#define BITS_TO_LONGS(nr) DIV_ROUND_UP(nr, BITS_PER_LONG)
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#define BITS_PER_BYTE 8
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#endif
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/*
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* Include this here because some architectures need generic_ffs/fls in
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* scope
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*/
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#include <asm/bitops.h>
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#define for_each_bit(bit, addr, size) \
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for ((bit) = find_first_bit((addr), (size)); \
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(bit) < (size); \
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(bit) = find_next_bit((addr), (size), (bit) + 1))
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static __inline__ int get_bitmask_order(unsigned int count)
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{
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int order;
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order = fls(count);
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return order; /* We could be slightly more clever with -1 here... */
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}
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static __inline__ int get_count_order(unsigned int count)
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{
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int order;
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order = fls(count) - 1;
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if (count & (count - 1))
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order++;
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return order;
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}
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static inline unsigned long hweight_long(unsigned long w)
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{
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return sizeof(w) == 4 ? hweight32(w) : hweight64(w);
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}
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/**
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* rol32 - rotate a 32-bit value left
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* @word: value to rotate
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* @shift: bits to roll
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*/
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static inline __u32 rol32(__u32 word, unsigned int shift)
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{
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return (word << shift) | (word >> (32 - shift));
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}
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/**
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* ror32 - rotate a 32-bit value right
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* @word: value to rotate
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* @shift: bits to roll
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*/
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static inline __u32 ror32(__u32 word, unsigned int shift)
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{
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return (word >> shift) | (word << (32 - shift));
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}
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/**
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* rol16 - rotate a 16-bit value left
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* @word: value to rotate
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* @shift: bits to roll
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*/
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static inline __u16 rol16(__u16 word, unsigned int shift)
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{
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return (word << shift) | (word >> (16 - shift));
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}
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/**
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* ror16 - rotate a 16-bit value right
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* @word: value to rotate
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* @shift: bits to roll
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*/
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static inline __u16 ror16(__u16 word, unsigned int shift)
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{
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return (word >> shift) | (word << (16 - shift));
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}
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/**
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* rol8 - rotate an 8-bit value left
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* @word: value to rotate
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* @shift: bits to roll
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*/
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static inline __u8 rol8(__u8 word, unsigned int shift)
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{
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return (word << shift) | (word >> (8 - shift));
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}
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/**
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* ror8 - rotate an 8-bit value right
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* @word: value to rotate
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* @shift: bits to roll
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*/
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static inline __u8 ror8(__u8 word, unsigned int shift)
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{
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return (word >> shift) | (word << (8 - shift));
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}
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static inline unsigned fls_long(unsigned long l)
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{
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if (sizeof(l) == 4)
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return fls(l);
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return fls64(l);
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}
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#ifdef __KERNEL__
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#ifdef CONFIG_GENERIC_FIND_FIRST_BIT
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extern unsigned long __find_first_bit(const unsigned long *addr,
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unsigned long size);
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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 size to search
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*
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* Returns the bit number of the first set bit.
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*/
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static __always_inline unsigned long
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find_first_bit(const unsigned long *addr, unsigned long size)
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{
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/* Avoid a function call if the bitmap size is a constant */
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/* and not bigger than BITS_PER_LONG. */
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/* insert a sentinel so that __ffs returns size if there */
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/* are no set bits in the bitmap */
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if (__builtin_constant_p(size) && (size < BITS_PER_LONG))
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return __ffs((*addr) | (1ul << size));
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/* the result of __ffs(0) is undefined, so it needs to be */
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/* handled separately */
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if (__builtin_constant_p(size) && (size == BITS_PER_LONG))
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return ((*addr) == 0) ? BITS_PER_LONG : __ffs(*addr);
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/* size is not constant or too big */
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return __find_first_bit(addr, size);
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}
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extern unsigned long __find_first_zero_bit(const unsigned long *addr,
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unsigned long size);
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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 size to search
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*
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* Returns the bit number of the first cleared bit.
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*/
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static __always_inline unsigned long
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find_first_zero_bit(const unsigned long *addr, unsigned long size)
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{
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/* Avoid a function call if the bitmap size is a constant */
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/* and not bigger than BITS_PER_LONG. */
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/* insert a sentinel so that __ffs returns size if there */
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/* are no set bits in the bitmap */
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if (__builtin_constant_p(size) && (size < BITS_PER_LONG)) {
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return __ffs(~(*addr) | (1ul << size));
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}
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/* the result of __ffs(0) is undefined, so it needs to be */
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/* handled separately */
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if (__builtin_constant_p(size) && (size == BITS_PER_LONG))
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return (~(*addr) == 0) ? BITS_PER_LONG : __ffs(~(*addr));
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/* size is not constant or too big */
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return __find_first_zero_bit(addr, size);
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}
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#endif /* CONFIG_GENERIC_FIND_FIRST_BIT */
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#ifdef CONFIG_GENERIC_FIND_NEXT_BIT
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extern unsigned long __find_next_bit(const unsigned long *addr,
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unsigned long size, unsigned long offset);
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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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* @offset: The bitnumber to start searching at
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* @size: The bitmap size in bits
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*/
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static __always_inline unsigned long
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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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unsigned long value;
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/* Avoid a function call if the bitmap size is a constant */
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/* and not bigger than BITS_PER_LONG. */
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/* insert a sentinel so that __ffs returns size if there */
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/* are no set bits in the bitmap */
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if (__builtin_constant_p(size) && (size < BITS_PER_LONG)) {
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value = (*addr) & ((~0ul) << offset);
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value |= (1ul << size);
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return __ffs(value);
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}
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/* the result of __ffs(0) is undefined, so it needs to be */
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/* handled separately */
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if (__builtin_constant_p(size) && (size == BITS_PER_LONG)) {
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value = (*addr) & ((~0ul) << offset);
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return (value == 0) ? BITS_PER_LONG : __ffs(value);
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}
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/* size is not constant or too big */
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return __find_next_bit(addr, size, offset);
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}
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extern unsigned long __find_next_zero_bit(const unsigned long *addr,
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unsigned long size, unsigned long offset);
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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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* @offset: The bitnumber to start searching at
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* @size: The bitmap size in bits
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*/
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static __always_inline unsigned long
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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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unsigned long value;
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/* Avoid a function call if the bitmap size is a constant */
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/* and not bigger than BITS_PER_LONG. */
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/* insert a sentinel so that __ffs returns size if there */
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/* are no set bits in the bitmap */
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if (__builtin_constant_p(size) && (size < BITS_PER_LONG)) {
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value = (~(*addr)) & ((~0ul) << offset);
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value |= (1ul << size);
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return __ffs(value);
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}
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/* the result of __ffs(0) is undefined, so it needs to be */
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/* handled separately */
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if (__builtin_constant_p(size) && (size == BITS_PER_LONG)) {
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value = (~(*addr)) & ((~0ul) << offset);
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return (value == 0) ? BITS_PER_LONG : __ffs(value);
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}
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/* size is not constant or too big */
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return __find_next_zero_bit(addr, size, offset);
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}
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#endif /* CONFIG_GENERIC_FIND_NEXT_BIT */
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#endif /* __KERNEL__ */
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#endif
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