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251 linhas
7.3 KiB
251 linhas
7.3 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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typedef struct {
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volatile int counter;
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} atomic_t;
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static inline int atomic_read(const atomic_t *v) __attribute__((always_inline));
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static inline void atomic_set(atomic_t *v, int i) __attribute__((always_inline));
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static inline void atomic_add(atomic_t *v, int i) __attribute__((always_inline));
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static inline void atomic_sub(atomic_t *v, int i) __attribute__((always_inline));
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static inline bool atomic_sub_test_zero(atomic_t *v, int i) __attribute__((always_inline));
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static inline void atomic_inc(atomic_t *v) __attribute__((always_inline));
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static inline void atomic_dec(atomic_t *v) __attribute__((always_inline));
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static inline bool atomic_inc_test_zero(atomic_t *v) __attribute__((always_inline));
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static inline bool atomic_dec_test_zero(atomic_t *v) __attribute__((always_inline));
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static inline int atomic_add_return(atomic_t *v, int i) __attribute__((always_inline));
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static inline int atomic_sub_return(atomic_t *v, int i) __attribute__((always_inline));
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/* *
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* atomic_read - read atomic variable
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* @v: pointer of type atomic_t
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*
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* Atomically reads the value of @v.
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* */
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static inline int
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atomic_read(const atomic_t *v) {
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return v->counter;
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}
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/* *
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* atomic_set - set atomic variable
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* @v: pointer of type atomic_t
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* @i: required value
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*
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* Atomically sets the value of @v to @i.
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* */
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static inline void
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atomic_set(atomic_t *v, int i) {
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v->counter = i;
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}
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/* *
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* atomic_add - add integer to atomic variable
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* @v: pointer of type atomic_t
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* @i: integer value to add
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*
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* Atomically adds @i to @v.
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* */
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static inline void
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atomic_add(atomic_t *v, int i) {
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asm volatile ("addl %1, %0" : "+m" (v->counter) : "ir" (i));
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}
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/* *
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* atomic_sub - subtract integer from atomic variable
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* @v: pointer of type atomic_t
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* @i: integer value to subtract
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*
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* Atomically subtracts @i from @v.
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* */
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static inline void
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atomic_sub(atomic_t *v, int i) {
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asm volatile("subl %1, %0" : "+m" (v->counter) : "ir" (i));
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}
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/* *
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* atomic_sub_test_zero - subtract value from variable and test result
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* @v: pointer of type atomic_t
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* @i: integer value to subtract
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*
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* Atomically subtracts @i from @v and
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* returns true if the result is zero, or false for all other cases.
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* */
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static inline bool
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atomic_sub_test_zero(atomic_t *v, int i) {
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unsigned char c;
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asm volatile("subl %2, %0; sete %1" : "+m" (v->counter), "=qm" (c) : "ir" (i) : "memory");
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return c != 0;
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}
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/* *
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* atomic_inc - increment atomic variable
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* @v: pointer of type atomic_t
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*
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* Atomically increments @v by 1.
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* */
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static inline void
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atomic_inc(atomic_t *v) {
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asm volatile("incl %0" : "+m" (v->counter));
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}
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/* *
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* atomic_dec - decrement atomic variable
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* @v: pointer of type atomic_t
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*
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* Atomically decrements @v by 1.
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* */
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static inline void
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atomic_dec(atomic_t *v) {
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asm volatile("decl %0" : "+m" (v->counter));
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}
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/* *
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* atomic_inc_test_zero - increment and test
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* @v: pointer of type atomic_t
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*
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* Atomically increments @v by 1 and
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* returns true if the result is zero, or false for all other cases.
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* */
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static inline bool
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atomic_inc_test_zero(atomic_t *v) {
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unsigned char c;
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asm volatile("incl %0; sete %1" : "+m" (v->counter), "=qm" (c) :: "memory");
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return c != 0;
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}
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/* *
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* atomic_dec_test_zero - decrement and test
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* @v: pointer of type atomic_t
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*
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* Atomically decrements @v by 1 and
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* returns true if the result is 0, or false for all other cases.
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* */
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static inline bool
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atomic_dec_test_zero(atomic_t *v) {
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unsigned char c;
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asm volatile("decl %0; sete %1" : "+m" (v->counter), "=qm" (c) :: "memory");
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return c != 0;
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}
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/* *
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* atomic_add_return - add integer and return
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* @i: integer value to add
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* @v: pointer of type atomic_t
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*
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* Atomically adds @i to @v and returns @i + @v
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* Requires Modern 486+ processor
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* */
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static inline int
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atomic_add_return(atomic_t *v, int i) {
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int __i = i;
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asm volatile("xaddl %0, %1" : "+r" (i), "+m" (v->counter) :: "memory");
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return i + __i;
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}
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/* *
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* atomic_sub_return - subtract integer and return
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* @v: pointer of type atomic_t
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* @i: integer value to subtract
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*
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* Atomically subtracts @i from @v and returns @v - @i
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* */
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static inline int
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atomic_sub_return(atomic_t *v, int i) {
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return atomic_add_return(v, -i);
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}
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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_and_set_bit(int nr, volatile void *addr) __attribute__((always_inline));
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static inline bool test_and_clear_bit(int nr, volatile void *addr) __attribute__((always_inline));
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static inline bool test_and_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_and_set_bit - Atomically set a bit and return its old value
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* @nr: the bit to set
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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_and_set_bit(int nr, volatile void *addr) {
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int oldbit;
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asm volatile ("btsl %2, %1; sbbl %0, %0" : "=r" (oldbit), "=m" (*(volatile long *)addr) : "Ir" (nr) : "memory");
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return oldbit != 0;
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}
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/* *
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* test_and_clear_bit - Atomically clear a bit and return its old value
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* @nr: the bit to clear
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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_and_clear_bit(int nr, volatile void *addr) {
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int oldbit;
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asm volatile ("btrl %2, %1; sbbl %0, %0" : "=r" (oldbit), "=m" (*(volatile long *)addr) : "Ir" (nr) : "memory");
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return oldbit != 0;
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}
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/* *
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* test_and_change_bit - Atomically change a bit and return its old value
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* @nr: the bit to change
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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_and_change_bit(int nr, volatile void *addr) {
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int oldbit;
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asm volatile ("btcl %2, %1; sbbl %0, %0" : "=r" (oldbit), "=m" (*(volatile long *)addr) : "Ir" (nr) : "memory");
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return oldbit != 0;
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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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