musl/arch/arm/atomic_arch.h

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__attribute__((__visibility__("hidden")))
extern const void *__arm_atomics[3]; /* gettp, cas, barrier */
#if ((__ARM_ARCH_6__ || __ARM_ARCH_6K__ || __ARM_ARCH_6ZK__) && !__thumb__) \
|| __ARM_ARCH_7A__ || __ARM_ARCH_7R__ || __ARM_ARCH >= 7
#define a_ll a_ll
static inline int a_ll(volatile int *p)
{
int v;
__asm__ __volatile__ ("ldrex %0, %1" : "=r"(v) : "Q"(*p));
return v;
}
#define a_sc a_sc
static inline int a_sc(volatile int *p, int v)
{
int r;
__asm__ __volatile__ ("strex %0,%2,%1" : "=&r"(r), "=Q"(*p) : "r"(v) : "memory");
return !r;
}
#if __ARM_ARCH_7A__ || __ARM_ARCH_7R__ || __ARM_ARCH >= 7
#define a_barrier a_barrier
static inline void a_barrier()
{
__asm__ __volatile__ ("dmb ish" : : : "memory");
}
#endif
#define a_pre_llsc a_barrier
#define a_post_llsc a_barrier
#else
#define a_cas a_cas
static inline int a_cas(volatile int *p, int t, int s)
{
for (;;) {
register int r0 __asm__("r0") = t;
register int r1 __asm__("r1") = s;
register volatile int *r2 __asm__("r2") = p;
int old;
__asm__ __volatile__ (
"bl __a_cas"
: "+r"(r0) : "r"(r1), "r"(r2)
: "memory", "r3", "lr", "ip", "cc" );
if (!r0) return t;
if ((old=*p)!=t) return old;
}
}
#endif
#ifndef a_barrier
#define a_barrier a_barrier
static inline void a_barrier()
{
__asm__ __volatile__("bl __a_barrier"
: : : "memory", "cc", "ip", "lr" );
}
#endif
#define a_crash a_crash
static inline void a_crash()
{
__asm__ __volatile__(
#ifndef __thumb__
".word 0xe7f000f0"
#else
".short 0xdeff"
#endif
: : : "memory");
}