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161 lines
3.0 KiB
161 lines
3.0 KiB
#ifndef _LINUX_BITOPS_H
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#define _LINUX_BITOPS_H
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#include <linux/types.h>
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#define BITS_PER_LONG 32
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/**
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* fls - find last (most-significant) bit set
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* @x: the word to search
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*
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* This is defined the same way as ffs.
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* Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.
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*/
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static inline int generic_fls(int x)
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{
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int r = 32;
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if (!x)
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return 0;
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if (!(x & 0xffff0000u)) {
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x <<= 16;
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r -= 16;
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}
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if (!(x & 0xff000000u)) {
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x <<= 8;
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r -= 8;
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}
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if (!(x & 0xf0000000u)) {
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x <<= 4;
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r -= 4;
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}
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if (!(x & 0xc0000000u)) {
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x <<= 2;
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r -= 2;
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}
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if (!(x & 0x80000000u)) {
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x <<= 1;
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r -= 1;
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}
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return r;
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}
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/**
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* ffs - find first bit set
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* @x: the word to search
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*
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* This is defined the same way as
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* the libc and compiler builtin ffs routines, therefore
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* differs in spirit from the above ffz (man ffs).
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*/
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static inline int generic_ffs(int x)
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{
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int r = 1;
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if (!x)
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return 0;
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if (!(x & 0xffff)) {
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x >>= 16;
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r += 16;
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}
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if (!(x & 0xff)) {
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x >>= 8;
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r += 8;
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}
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if (!(x & 0xf)) {
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x >>= 4;
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r += 4;
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}
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if (!(x & 3)) {
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x >>= 2;
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r += 2;
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}
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if (!(x & 1)) {
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x >>= 1;
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r += 1;
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}
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return r;
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}
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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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/* linux/include/asm-generic/bitops/non-atomic.h */
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#ifndef PLATFORM__SET_BIT
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# define __set_bit generic_set_bit
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#endif
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#ifndef PLATFORM__CLEAR_BIT
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# define __clear_bit generic_clear_bit
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#endif
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#ifndef PLATFORM_FFS
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# define ffs generic_ffs
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#endif
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#ifndef PLATFORM_FLS
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# define fls generic_fls
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#endif
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/**
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* __set_bit - Set a bit in memory
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* @nr: the bit to set
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* @addr: the address to start counting from
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*
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* Unlike set_bit(), this function is non-atomic and may be reordered.
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* If it's called on the same region of memory simultaneously, the effect
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* may be that only one operation succeeds.
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*/
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static inline void generic_set_bit(int nr, volatile unsigned long *addr)
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{
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unsigned long mask = BIT_MASK(nr);
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unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
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*p |= mask;
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}
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static inline void generic_clear_bit(int nr, volatile unsigned long *addr)
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{
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unsigned long mask = BIT_MASK(nr);
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unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
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*p &= ~mask;
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}
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/*
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* test_bit - Determine whether a bit is set
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* @nr: bit number to test
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* @addr: Address to start counting from
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*/
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static __inline__ int test_bit(int nr, volatile void *addr)
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{
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return ((1UL << (nr & 31)) & (((const unsigned int *) addr)[nr >> 5])) != 0;
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}
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/*
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* test_and_set_bit - Set a bit and return its old value
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* @nr: Bit to set
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* @addr: Address to count from
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*
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* This operation is non-atomic and can be reordered.
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* If two examples of this operation race, one can appear to succeed
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* but actually fail. You must protect multiple accesses with a lock.
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*/
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static __inline__ int test_and_set_bit(int nr, volatile void * addr)
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{
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int mask, retval;
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volatile int *a = addr;
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a += nr >> 5;
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mask = 1 << (nr & 0x1f);
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retval = (mask & *a) != 0;
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*a |= mask;
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return retval;
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}
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#endif
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