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1275 |
phoenix |
/* atomic.h: These still suck, but the I-cache hit rate is higher.
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*
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* Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
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* Copyright (C) 2000 Anton Blanchard (anton@linuxcare.com.au)
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*/
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#ifndef __ARCH_SPARC_ATOMIC__
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#define __ARCH_SPARC_ATOMIC__
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#include <linux/config.h>
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typedef struct { volatile int counter; } atomic_t;
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#ifdef __KERNEL__
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#ifndef CONFIG_SMP
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#define ATOMIC_INIT(i) { (i) }
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#define atomic_read(v) ((v)->counter)
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#define atomic_set(v, i) (((v)->counter) = i)
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#else
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/* We do the bulk of the actual work out of line in two common
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* routines in assembler, see arch/sparc/lib/atomic.S for the
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* "fun" details.
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*
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* For SMP the trick is you embed the spin lock byte within
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* the word, use the low byte so signedness is easily retained
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* via a quick arithmetic shift. It looks like this:
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*
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* ----------------------------------------
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* | signed 24-bit counter value | lock | atomic_t
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* ----------------------------------------
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* 31 8 7 0
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*/
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#define ATOMIC_INIT(i) { (i << 8) }
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static __inline__ int atomic_read(atomic_t *v)
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{
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int ret = v->counter;
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while(ret & 0xff)
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ret = v->counter;
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return ret >> 8;
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}
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#define atomic_set(v, i) (((v)->counter) = ((i) << 8))
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#endif
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static inline int __atomic_add(int i, atomic_t *v)
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{
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register volatile int *ptr asm("g1");
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register int increment asm("g2");
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register int tmp1 asm("g3");
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register int tmp2 asm("g4");
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register int tmp3 asm("g7");
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ptr = &v->counter;
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increment = i;
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__asm__ __volatile__(
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"mov %%o7, %%g4\n\t"
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"call ___atomic_add\n\t"
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" add %%o7, 8, %%o7\n"
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: "=&r" (increment), "=r" (tmp1), "=r" (tmp2), "=r" (tmp3)
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: "0" (increment), "r" (ptr)
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: "memory", "cc");
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return increment;
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}
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static inline int __atomic_sub(int i, atomic_t *v)
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{
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register volatile int *ptr asm("g1");
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register int increment asm("g2");
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register int tmp1 asm("g3");
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register int tmp2 asm("g4");
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register int tmp3 asm("g7");
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ptr = &v->counter;
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increment = i;
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__asm__ __volatile__(
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"mov %%o7, %%g4\n\t"
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"call ___atomic_sub\n\t"
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" add %%o7, 8, %%o7\n"
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: "=&r" (increment), "=r" (tmp1), "=r" (tmp2), "=r" (tmp3)
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: "0" (increment), "r" (ptr)
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: "memory", "cc");
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return increment;
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}
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#define atomic_add(i, v) ((void)__atomic_add((i), (v)))
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#define atomic_sub(i, v) ((void)__atomic_sub((i), (v)))
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#define atomic_dec_return(v) __atomic_sub(1, (v))
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#define atomic_inc_return(v) __atomic_add(1, (v))
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#define atomic_sub_and_test(i, v) (__atomic_sub((i), (v)) == 0)
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#define atomic_dec_and_test(v) (__atomic_sub(1, (v)) == 0)
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#define atomic_inc(v) ((void)__atomic_add(1, (v)))
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#define atomic_dec(v) ((void)__atomic_sub(1, (v)))
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#define atomic_add_negative(i, v) (__atomic_add((i), (v)) < 0)
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/* Atomic operations are already serializing */
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#define smp_mb__before_atomic_dec() barrier()
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#define smp_mb__after_atomic_dec() barrier()
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#define smp_mb__before_atomic_inc() barrier()
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#define smp_mb__after_atomic_inc() barrier()
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#endif /* !(__KERNEL__) */
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#endif /* !(__ARCH_SPARC_ATOMIC__) */
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