119 lines
2.1 KiB
C
119 lines
2.1 KiB
C
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/* ------------------------------- **
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** Atomic lock for ALPHA **
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** ------------------------------- */
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/* This code is stolen from the Linux kernel */
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static __inline__ int _test_and_set_bit(unsigned long nr,
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volatile void * addr)
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{
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unsigned long oldbit;
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unsigned long temp;
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unsigned int * m = ((unsigned int *) addr) + (nr >> 5);
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__asm__ __volatile__(
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"1: ldl_l %0,%1\n"
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" and %0,%3,%2\n"
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" bne %2,2f\n"
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" xor %0,%3,%0\n"
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" stl_c %0,%1\n"
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" beq %0,3f\n"
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" mb\n"
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"2:\n"
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".subsection 2\n"
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"3: br 1b\n"
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".previous"
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:"=&r" (temp), "=m" (*m), "=&r" (oldbit)
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:"Ir" (1UL << (nr & 31)), "m" (*m));
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return oldbit != 0;
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}
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static __inline__ void _spin_lock(volatile void *lock)
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{
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long tmp;
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/* Use sub-sections to put the actual loop at the end
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of this object file's text section so as to perfect
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branch prediction. */
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__asm__ __volatile__(
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"1: ldl_l %0,%1\n"
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" blbs %0,2f\n"
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" or %0,1,%0\n"
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" stl_c %0,%1\n"
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" beq %0,2f\n"
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" mb\n"
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".subsection 2\n"
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"2: ldl %0,%1\n"
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" blbs %0,2b\n"
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" br 1b\n"
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".previous"
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: "=r" (tmp), "=m" (__dummy_lock(lock))
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: "m"(__dummy_lock(lock)));
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}
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static inline void _write_lock(rwlock_t * lock)
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{
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long regx;
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__asm__ __volatile__(
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"1: ldl_l %1,%0\n"
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" bne %1,6f\n"
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" or $31,1,%1\n"
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" stl_c %1,%0\n"
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" beq %1,6f\n"
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" mb\n"
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".subsection 2\n"
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"6: ldl %1,%0\n"
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" bne %1,6b\n"
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" br 1b\n"
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".previous"
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: "=m" (__dummy_lock(lock)), "=&r" (regx)
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: "0" (__dummy_lock(lock))
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);
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}
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static inline void _read_lock(rwlock_t * lock)
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{
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long regx;
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__asm__ __volatile__(
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"1: ldl_l %1,%0\n"
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" blbs %1,6f\n"
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" subl %1,2,%1\n"
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" stl_c %1,%0\n"
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" beq %1,6f\n"
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"4: mb\n"
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".subsection 2\n"
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"6: ldl %1,%0\n"
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" blbs %1,6b\n"
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" br 1b\n"
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".previous"
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: "=m" (__dummy_lock(lock)), "=&r" (regx)
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: "m" (__dummy_lock(lock))
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);
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}
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static inline void _write_unlock(rwlock_t * lock)
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{
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mb();
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*(volatile int *)lock = 0;
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}
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static inline void _read_unlock(rwlock_t * lock)
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{
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long regx;
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__asm__ __volatile__(
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"1: ldl_l %1,%0\n"
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" addl %1,2,%1\n"
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" stl_c %1,%0\n"
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" beq %1,6f\n"
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".subsection 2\n"
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"6: br 1b\n"
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".previous"
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: "=m" (__dummy_lock(lock)), "=&r" (regx)
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: "m" (__dummy_lock(lock)));
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}
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