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57 rivejä
1.8 KiB
57 rivejä
1.8 KiB
#ifndef __LIBS_ATOMIC_H__
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#define __LIBS_ATOMIC_H__
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/* Atomic operations that C can't guarantee us. Useful for resource counting etc.. */
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static inline void set_bit(int nr, volatile void *addr) __attribute__((always_inline));
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static inline void clear_bit(int nr, volatile void *addr) __attribute__((always_inline));
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static inline void change_bit(int nr, volatile void *addr) __attribute__((always_inline));
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static inline bool test_bit(int nr, volatile void *addr) __attribute__((always_inline));
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/* *
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* set_bit - Atomically 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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* Note that @nr may be almost arbitrarily large; this function is not
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* restricted to acting on a single-word quantity.
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* */
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static inline void
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set_bit(int nr, volatile void *addr) {
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asm volatile ("btsl %1, %0" :"=m" (*(volatile long *)addr) : "Ir" (nr));
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}
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/* *
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* clear_bit - Atomically clears a bit in memory
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* @nr: the bit to clear
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* @addr: the address to start counting from
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* */
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static inline void
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clear_bit(int nr, volatile void *addr) {
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asm volatile ("btrl %1, %0" :"=m" (*(volatile long *)addr) : "Ir" (nr));
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}
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/* *
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* change_bit - Atomically toggle a bit in memory
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* @nr: the bit to change
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* @addr: the address to start counting from
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* */
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static inline void
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change_bit(int nr, volatile void *addr) {
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asm volatile ("btcl %1, %0" :"=m" (*(volatile long *)addr) : "Ir" (nr));
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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: the bit to test
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* @addr: the address to count from
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* */
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static inline bool
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test_bit(int nr, volatile void *addr) {
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int oldbit;
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asm volatile ("btl %2, %1; sbbl %0,%0" : "=r" (oldbit) : "m" (*(volatile long *)addr), "Ir" (nr));
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return oldbit != 0;
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}
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#endif /* !__LIBS_ATOMIC_H__ */
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