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/* atomic.h: These still suck, but the I-cache hit rate is higher.
*
* Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
*/
#ifndef __ARCH_SPARC_ATOMIC__
#define __ARCH_SPARC_ATOMIC__
#include <linux/config.h>
#ifdef CONFIG_SMP
/* This is a temporary measure. -DaveM */
typedef struct { volatile int counter; } atomic_t;
#define ATOMIC_INIT(i) { (i << 8) }
#else
typedef struct { int counter; } atomic_t;
#define ATOMIC_INIT(i) { (i) }
#endif
#ifdef __KERNEL__
#include <asm/system.h>
#include <asm/psr.h>
#ifndef CONFIG_SMP
#define atomic_read(v) ((v)->counter)
#define atomic_set(v, i) (((v)->counter) = i)
#else
/* We do the bulk of the actual work out of line in two common
* routines in assembler, see arch/sparc/lib/atomic.S for the
* "fun" details.
*
* For SMP the trick is you embed the spin lock byte within
* the word, use the low byte so signedness is easily retained
* via a quick arithmetic shift. It looks like this:
*
* ----------------------------------------
* | signed 24-bit counter value | lock | atomic_t
* ----------------------------------------
* 31 8 7 0
*/
static __inline__ int atomic_read(atomic_t *v)
{
int ret = v->counter;
while(ret & 0xff)
ret = v->counter;
return ret >> 8;
}
#define atomic_set(v, i) (((v)->counter) = ((i) << 8))
#endif
/* Make sure gcc doesn't try to be clever and move things around
* on us. We need to use _exactly_ the address the user gave us,
* not some alias that contains the same information.
*/
#define __atomic_fool_gcc(x) ((struct { int a[100]; } *)x)
static __inline__ void atomic_add(int i, atomic_t *v)
{
register atomic_t *ptr asm("g1");
register int increment asm("g2");
ptr = (atomic_t *) __atomic_fool_gcc(v);
increment = i;
__asm__ __volatile__("
mov %%o7, %%g4
call ___atomic_add
add %%o7, 8, %%o7
" : "=&r" (increment)
: "0" (increment), "r" (ptr)
: "g3", "g4", "g7", "memory", "cc");
}
static __inline__ void atomic_sub(int i, atomic_t *v)
{
register atomic_t *ptr asm("g1");
register int increment asm("g2");
ptr = (atomic_t *) __atomic_fool_gcc(v);
increment = i;
__asm__ __volatile__("
mov %%o7, %%g4
call ___atomic_sub
add %%o7, 8, %%o7
" : "=&r" (increment)
: "0" (increment), "r" (ptr)
: "g3", "g4", "g7", "memory", "cc");
}
static __inline__ int atomic_add_return(int i, atomic_t *v)
{
register atomic_t *ptr asm("g1");
register int increment asm("g2");
ptr = (atomic_t *) __atomic_fool_gcc(v);
increment = i;
__asm__ __volatile__("
mov %%o7, %%g4
call ___atomic_add
add %%o7, 8, %%o7
" : "=&r" (increment)
: "0" (increment), "r" (ptr)
: "g3", "g4", "g7", "memory", "cc");
return increment;
}
static __inline__ int atomic_sub_return(int i, atomic_t *v)
{
register atomic_t *ptr asm("g1");
register int increment asm("g2");
ptr = (atomic_t *) __atomic_fool_gcc(v);
increment = i;
__asm__ __volatile__("
mov %%o7, %%g4
call ___atomic_sub
add %%o7, 8, %%o7
" : "=&r" (increment)
: "0" (increment), "r" (ptr)
: "g3", "g4", "g7", "memory", "cc");
return increment;
}
#define atomic_dec_return(v) atomic_sub_return(1,(v))
#define atomic_inc_return(v) atomic_add_return(1,(v))
#define atomic_sub_and_test(i, v) (atomic_sub_return((i), (v)) == 0)
#define atomic_dec_and_test(v) (atomic_sub_return(1, (v)) == 0)
#define atomic_inc(v) atomic_add(1,(v))
#define atomic_dec(v) atomic_sub(1,(v))
#endif /* !(__KERNEL__) */
#endif /* !(__ARCH_SPARC_ATOMIC__) */
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