From a67c21f093202f142438689d3f7cfbdf4ea82eea Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Sun, 28 Oct 2007 19:13:50 +0000
Subject: merge 'lennart' branch back into trunk.

git-svn-id: file:///home/lennart/svn/public/pulseaudio/trunk@1971 fefdeb5f-60dc-0310-8127-8f9354f1896f
---
 src/pulsecore/atomic.h | 193 ++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 175 insertions(+), 18 deletions(-)

(limited to 'src/pulsecore/atomic.h')

diff --git a/src/pulsecore/atomic.h b/src/pulsecore/atomic.h
index 013e8c20..c2c99888 100644
--- a/src/pulsecore/atomic.h
+++ b/src/pulsecore/atomic.h
@@ -24,48 +24,201 @@
   USA.
 ***/
 
-#include <atomic_ops.h>
-
-/* atomic_ops guarantees us that sizeof(AO_t) == sizeof(void*).
+/*
+ * atomic_ops guarantees us that sizeof(AO_t) == sizeof(void*).  It is
+ * not guaranteed however, that sizeof(AO_t) == sizeof(size_t).
+ * however very likely.
+ *
+ * For now we do only full memory barriers. Eventually we might want
+ * to support more elaborate memory barriers, in which case we will add
+ * suffixes to the function names.
  *
- * It is not guaranteed however, that sizeof(AO_t) == sizeof(size_t).
- * however very likely. */
+ * On gcc >= 4.1 we use the builtin atomic functions. otherwise we use
+ * libatomic_ops
+ */
 
-typedef struct pa_atomic_int {
-    volatile AO_t value;
-} pa_atomic_int_t;
+#ifndef PACKAGE
+#error "Please include config.h before including this file!"
+#endif
+
+#ifdef HAVE_ATOMIC_BUILTINS
+
+/* __sync based implementation */
+
+typedef struct pa_atomic {
+    volatile int value;
+} pa_atomic_t;
 
 #define PA_ATOMIC_INIT(v) { .value = (v) }
 
-/* For now we do only full memory barriers. Eventually we might want
- * to support more elaborate memory barriers, in which case we will add
- * suffixes to the function names */
+static inline int pa_atomic_load(const pa_atomic_t *a) {
+    __sync_synchronize();
+    return a->value;
+}
+
+static inline void pa_atomic_store(pa_atomic_t *a, int i) {
+    a->value = i;
+    __sync_synchronize();
+}
+
+/* Returns the previously set value */
+static inline int pa_atomic_add(pa_atomic_t *a, int i) {
+    return __sync_fetch_and_add(&a->value, i);
+}
+
+/* Returns the previously set value */
+static inline int pa_atomic_sub(pa_atomic_t *a, int i) {
+    return __sync_fetch_and_sub(&a->value, i);
+}
+
+/* Returns the previously set value */
+static inline int pa_atomic_inc(pa_atomic_t *a) {
+    return pa_atomic_add(a, 1);
+}
+
+/* Returns the previously set value */
+static inline int pa_atomic_dec(pa_atomic_t *a) {
+    return pa_atomic_sub(a, 1);
+}
+
+/* Returns non-zero when the operation was successful. */
+static inline int pa_atomic_cmpxchg(pa_atomic_t *a, int old_i, int new_i) {
+    return __sync_bool_compare_and_swap(&a->value, old_i, new_i);
+}
+
+typedef struct pa_atomic_ptr {
+    volatile unsigned long value;
+} pa_atomic_ptr_t;
+
+#define PA_ATOMIC_PTR_INIT(v) { .value = (long) (v) }
+
+static inline void* pa_atomic_ptr_load(const pa_atomic_ptr_t *a) {
+    __sync_synchronize();
+    return (void*) a->value;
+}
+
+static inline void pa_atomic_ptr_store(pa_atomic_ptr_t *a, void *p) {
+    a->value = (unsigned long) p;
+    __sync_synchronize();
+}
+
+static inline int pa_atomic_ptr_cmpxchg(pa_atomic_ptr_t *a, void *old_p, void* new_p) {
+    return __sync_bool_compare_and_swap(&a->value, (long) old_p, (long) new_p);
+}
+
+#elif defined(__GNUC__) && (defined(__amd64__) || defined(__x86_64__))
+
+#error "The native atomic operations implementation for AMD64 has not been tested. libatomic_ops is known to not work properly on AMD64 and your gcc version is too old for the gcc-builtin atomic ops support. You have three options now: make the native atomic operations implementation for AMD64 work, fix libatomic_ops, or upgrade your GCC."
+
+/* Addapted from glibc */
+
+typedef struct pa_atomic {
+    volatile int value;
+} pa_atomic_t;
+
+#define PA_ATOMIC_INIT(v) { .value = (v) }
+
+static inline int pa_atomic_load(const pa_atomic_t *a) {
+    return a->value;
+}
+
+static inline void pa_atomic_store(pa_atomic_t *a, int i) {
+    a->value = i;
+}
+
+static inline int pa_atomic_add(pa_atomic_t *a, int i) {
+    int result;
+
+    __asm __volatile ("lock; xaddl %0, %1"
+                      : "=r" (result), "=m" (a->value)
+                      : "0" (i), "m" (a->value));
+
+    return result;
+}
+
+static inline int pa_atomic_sub(pa_atomic_t *a, int i) {
+    return pa_atomic_add(a, -i);
+}
+
+static inline int pa_atomic_inc(pa_atomic_t *a) {
+    return pa_atomic_add(a, 1);
+}
 
-static inline int pa_atomic_load(const pa_atomic_int_t *a) {
+static inline int pa_atomic_dec(pa_atomic_t *a) {
+    return pa_atomic_sub(a, 1);
+}
+
+static inline int pa_atomic_cmpxchg(pa_atomic_t *a, int old_i, int new_i) {
+    int result;
+
+    __asm__ __volatile__ ("lock; cmpxchgl %2, %1"
+                          : "=a" (result), "=m" (a->value)
+                          : "r" (new_i), "m" (a->value), "0" (old_i));
+
+    return result == oldval;
+}
+
+typedef struct pa_atomic_ptr {
+    volatile unsigned long value;
+} pa_atomic_ptr_t;
+
+#define PA_ATOMIC_PTR_INIT(v) { .value = (long) (v) }
+
+static inline void* pa_atomic_ptr_load(const pa_atomic_ptr_t *a) {
+    return (void*) a->value;
+}
+
+static inline void pa_atomic_ptr_store(pa_atomic_ptr_t *a, void *p) {
+    a->value = (unsigned long) p;
+}
+
+static inline int pa_atomic_ptr_cmpxchg(pa_atomic_ptr_t *a, void *old_p, void* new_p) {
+    void *result;
+
+    __asm__ __volatile__ ("lock; cmpxchgq %q2, %1"
+                          : "=a" (result), "=m" (a->value)
+                          : "r" (new_p), "m" (a->value), "0" (old_p));
+
+    return result;
+}
+
+#else
+
+/* libatomic_ops based implementation */
+
+#include <atomic_ops.h>
+
+typedef struct pa_atomic {
+    volatile AO_t value;
+} pa_atomic_t;
+
+#define PA_ATOMIC_INIT(v) { .value = (v) }
+
+static inline int pa_atomic_load(const pa_atomic_t *a) {
     return (int) AO_load_full((AO_t*) &a->value);
 }
 
-static inline void pa_atomic_store(pa_atomic_int_t *a, int i) {
+static inline void pa_atomic_store(pa_atomic_t *a, int i) {
     AO_store_full(&a->value, (AO_t) i);
 }
 
-static inline int pa_atomic_add(pa_atomic_int_t *a, int i) {
+static inline int pa_atomic_add(pa_atomic_t *a, int i) {
     return AO_fetch_and_add_full(&a->value, (AO_t) i);
 }
 
-static inline int pa_atomic_sub(pa_atomic_int_t *a, int i) {
+static inline int pa_atomic_sub(pa_atomic_t *a, int i) {
     return AO_fetch_and_add_full(&a->value, (AO_t) -i);
 }
 
-static inline int pa_atomic_inc(pa_atomic_int_t *a) {
+static inline int pa_atomic_inc(pa_atomic_t *a) {
     return AO_fetch_and_add1_full(&a->value);
 }
 
-static inline int pa_atomic_dec(pa_atomic_int_t *a) {
+static inline int pa_atomic_dec(pa_atomic_t *a) {
     return AO_fetch_and_sub1_full(&a->value);
 }
 
-static inline int pa_atomic_cmpxchg(pa_atomic_int_t *a, int old_i, int new_i) {
+static inline int pa_atomic_cmpxchg(pa_atomic_t *a, int old_i, int new_i) {
     return AO_compare_and_swap_full(&a->value, old_i, new_i);
 }
 
@@ -73,6 +226,8 @@ typedef struct pa_atomic_ptr {
     volatile AO_t value;
 } pa_atomic_ptr_t;
 
+#define PA_ATOMIC_PTR_INIT(v) { .value = (AO_t) (v) }
+
 static inline void* pa_atomic_ptr_load(const pa_atomic_ptr_t *a) {
     return (void*) AO_load_full((AO_t*) &a->value);
 }
@@ -86,3 +241,5 @@ static inline int pa_atomic_ptr_cmpxchg(pa_atomic_ptr_t *a, void *old_p, void* n
 }
 
 #endif
+
+#endif
-- 
cgit