fpm_atomic.h

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    /* (c) 2007,2008 Andrei Nigmatulin */
 
#ifndef FPM_ATOMIC_H
#define FPM_ATOMIC_H 1
 
#include <inttypes.h>
#include <sched.h>
 
#ifdef HAVE_BUILTIN_ATOMIC

 
typedef volatile unsigned long atomic_t;
#define atomic_cmp_set(a,b,c) __sync_bool_compare_and_swap(a,b,c)
 
#elif ( __i386__ || __i386 )
 
typedef int32_t                     atomic_int_t;
typedef uint32_t                    atomic_uint_t;
typedef volatile atomic_uint_t      atomic_t;
 
 
static inline atomic_int_t atomic_fetch_add(atomic_t *value, atomic_int_t add) /* {{{ */
{
    __asm__ volatile ( "lock;" "xaddl %0, %1;" :
        "+r" (add) : "m" (*value) : "memory");
 
    return add;
}
/* }}} */
 
static inline atomic_uint_t atomic_cmp_set(atomic_t *lock, atomic_uint_t old, atomic_uint_t set) /* {{{ */
{
    unsigned char res;
 
    __asm__ volatile ( "lock;" "cmpxchgl %3, %1;" "sete %0;" :
        "=a" (res) : "m" (*lock), "a" (old), "r" (set) : "memory");
 
    return res;
}
/* }}} */
 
#elif ( __amd64__ || __amd64 || __x86_64__ )
 
typedef int64_t                     atomic_int_t;
typedef uint64_t                    atomic_uint_t;
typedef volatile atomic_uint_t      atomic_t;
 
static inline atomic_int_t atomic_fetch_add(atomic_t *value, atomic_int_t add) /* {{{ */
{
    __asm__ volatile ( "lock;" "xaddq %0, %1;" :
        "+r" (add) : "m" (*value) : "memory");
 
    return add;
}
/* }}} */
 
static inline atomic_uint_t atomic_cmp_set(atomic_t *lock, atomic_uint_t old, atomic_uint_t set) /* {{{ */
{
    unsigned char res;
 
    __asm__ volatile ( "lock;" "cmpxchgq %3, %1;" "sete %0;" :
        "=a" (res) : "m" (*lock), "a" (old), "r" (set) : "memory");
 
    return res;
}
/* }}} */
 
#if (__GNUC__) && (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 2))
 
#elif ( __arm__ || __arm ) /* W-Mark Kubacki */
 
#if (__arch64__ || __arch64)
typedef int64_t                     atomic_int_t;
typedef uint64_t                    atomic_uint_t;
#else
typedef int32_t                     atomic_int_t;
typedef uint32_t                    atomic_uint_t;
#endif
 
#define atomic_cmp_set(a,b,c) __sync_bool_compare_and_swap(a,b,c)
 
#endif /* defined (__GNUC__) &&... */
 
#elif ( __sparc__ || __sparc ) /* Marcin Ochab */
 
#if (__sparcv9 || __sparcv9__)
 
#if (__arch64__ || __arch64)
typedef uint64_t                    atomic_uint_t;
typedef volatile atomic_uint_t      atomic_t;
 
static inline atomic_uint_t atomic_cas_64(atomic_t *lock, atomic_uint_t old, atomic_uint_t new) /* {{{ */
{
    __asm__ __volatile__("casx [%2], %3, %0 " : "=&r"(new)  : "0"(new), "r"(lock), "r"(old): "memory");
 
    return new;
}
/* }}} */
 
static inline atomic_uint_t atomic_cmp_set(atomic_t *lock, atomic_uint_t old, atomic_uint_t set) /* {{{ */
{
    return (atomic_cas_64(lock, old, set)==old);
}
/* }}} */
#else
typedef uint32_t                    atomic_uint_t;
typedef volatile atomic_uint_t      atomic_t;
 
static inline atomic_uint_t atomic_cas_32(atomic_t *lock, atomic_uint_t old, atomic_uint_t new) /* {{{ */
{
    __asm__ __volatile__("cas [%2], %3, %0 " : "=&r"(new)  : "0"(new), "r"(lock), "r"(old): "memory");
 
    return new;
}
/* }}} */
 
static inline atomic_uint_t atomic_cmp_set(atomic_t *lock, atomic_uint_t old, atomic_uint_t set) /* {{{ */
{
    return (atomic_cas_32(lock, old, set)==old);
}
/* }}} */
#endif
 
#else /* #if (__sparcv9 || __sparcv9__) */
#error Sparc v8 and predecessors are not and will not be supported (see bug report 53310)
#endif /* #if (__sparcv9 || __sparcv9__) */
 
#else
 
#error Unsupported processor. Please open a bug report (https://github.com/php/php-src/issues).
 
#endif
 
static inline int fpm_spinlock(atomic_t *lock, int try_once) /* {{{ */
{
    if (try_once) {
        return atomic_cmp_set(lock, 0, 1) ? 1 : 0;
    }
 
    for (;;) {
 
        if (atomic_cmp_set(lock, 0, 1)) {
            break;
        }
 
        sched_yield();
    }
 
    return 1;
}
/* }}} */
 
static inline int fpm_spinlock_with_max_retries(atomic_t *lock, unsigned int max_retries)
{
    unsigned int retries = 0;
 
    for (;;) {
        if (atomic_cmp_set(lock, 0, 1)) {
            return 1;
        }
 
        sched_yield();
 
        if (++retries > max_retries) {
            return 0;
        }
    }
 
    return 1;
}
 
#define fpm_unlock(lock) lock = 0
 
#endif