Introduce apr_atomic_xchgptr, which atomically exchanges a pair of pointer

values. Missing OS/390 implementation.


git-svn-id: https://svn.apache.org/repos/asf/apr/apr/trunk@554995 13f79535-47bb-0310-9956-ffa450edef68

8 files changed, 116 insertions, 0 deletions

diff --git a/atomic/netware/apr_atomic.c b/atomic/netware/apr_atomic.c
index 94a354977..b5d965b09 100644
--- a/atomic/netware/apr_atomic.c
+++ b/atomic/netware/apr_atomic.c
@@ -68,3 +68,8 @@ APR_DECLARE(void *) apr_atomic_casptr(volatile void **mem, void *with, const voi
 {
     return (void*)atomic_cmpxchg((unsigned long *)mem,(unsigned long)cmp,(unsigned long)with);
 }
+
+APR_DECLARE(void*) apr_atomic_xchgptr(volatile void **mem, void *with)
+{
+    return (void*)atomic_xchg((unsigned long *)mem,(unsigned long)with);
+}
diff --git a/atomic/unix/builtins.c b/atomic/unix/builtins.c
index 274599614..745acf155 100644
--- a/atomic/unix/builtins.c
+++ b/atomic/unix/builtins.c
@@ -71,4 +71,11 @@ APR_DECLARE(void*) apr_atomic_casptr(volatile void **mem, void *with, const void
     return (void*) __sync_val_compare_and_swap(mem, cmp, with);
 }
 
+APR_DECLARE(void*) apr_atomic_xchgptr(volatile void **mem, void *with)
+{
+    __sync_synchronize();
+
+    return (void*) __sync_lock_test_and_set(mem, with);
+}
+
 #endif /* USE_ATOMICS_BUILTINS */
diff --git a/atomic/unix/ia32.c b/atomic/unix/ia32.c
index bcf9d5661..191298c4a 100644
--- a/atomic/unix/ia32.c
+++ b/atomic/unix/ia32.c
@@ -108,4 +108,23 @@ APR_DECLARE(void*) apr_atomic_casptr(volatile void **mem, void *with, const void
     return prev;
 }
 
+APR_DECLARE(void*) apr_atomic_xchgptr(volatile void **mem, void *with)
+{
+    void *prev;
+#if APR_SIZEOF_VOIDP == 4
+    asm volatile ("lock; xchgl %2, %1"
+                  : "=a" (prev), "=m" (*mem)
+                  : "r" (with), "m" (*mem)
+                  : "memory");
+#elif APR_SIZEOF_VOIDP == 8
+    asm volatile ("lock; xchgq %q2, %1"
+                  : "=a" (prev), "=m" (*mem)
+                  : "r" ((unsigned long)with), "m" (*mem)
+                  : "memory");
+#else
+#error APR_SIZEOF_VOIDP value not supported
+#endif
+    return prev;
+}
+
 #endif /* USE_ATOMICS_IA32 */
diff --git a/atomic/unix/mutex.c b/atomic/unix/mutex.c
index 17b605fcd..cb23ede34 100644
--- a/atomic/unix/mutex.c
+++ b/atomic/unix/mutex.c
@@ -189,4 +189,17 @@ APR_DECLARE(void*) apr_atomic_casptr(volatile void **mem, void *with, const void
     return prev;
 }
 
+APR_DECLARE(void*) apr_atomic_xchgptr(volatile void **mem, void *with)
+{
+    void *prev;
+    DECLARE_MUTEX_LOCKED(mutex, mem);
+
+    prev = *mem;
+    *mem = with;
+
+    MUTEX_UNLOCK(mutex);
+
+    return prev;
+}
+
 #endif /* USE_ATOMICS_GENERIC */
diff --git a/atomic/unix/ppc.c b/atomic/unix/ppc.c
index 149347eae..d7673d5ee 100644
--- a/atomic/unix/ppc.c
+++ b/atomic/unix/ppc.c
@@ -175,4 +175,35 @@ APR_DECLARE(void*) apr_atomic_casptr(volatile void **mem, void *with, const void
     return prev;
 }
 
+APR_DECLARE(void*) apr_atomic_xchgptr(volatile void **mem, void *with)
+{
+    void *prev;
+#if APR_SIZEOF_VOIDP == 4
+    asm volatile (PPC_SYNC
+                  "loop_%=:\n"                  /* lost reservation     */
+                  "	lwarx   %0,0,%1\n"      /* load and reserve     */
+                  PPC405_ERR77_SYNC             /* ppc405 Erratum 77    */
+                  "	stwcx.  %2,0,%1\n"      /* store new value      */
+                  "	bne-    loop_%=\n"      /* loop if lost         */
+                  "	isync\n"                /* memory barrier       */
+                  : "=&r" (prev)
+                  : "b" (mem), "r" (with)
+                  : "cc", "memory");
+#elif APR_SIZEOF_VOIDP == 8
+    asm volatile (PPC_SYNC
+                  "loop_%=:\n"                  /* lost reservation     */
+                  "	ldarx   %0,0,%1\n"      /* load and reserve     */
+                  PPC405_ERR77_SYNC             /* ppc405 Erratum 77    */
+                  "	stdcx.  %2,0,%1\n"      /* store new value      */
+                  "	bne-    loop_%=\n"      /* loop if lost         */
+                  "	isync\n"                /* memory barrier       */
+                  : "=&r" (prev)
+                  : "b" (mem), "r" (with)
+                  : "cc", "memory");
+#else
+#error APR_SIZEOF_VOIDP value not supported
+#endif
+    return prev;
+}
+
 #endif /* USE_ATOMICS_PPC */
diff --git a/atomic/unix/s390.c b/atomic/unix/s390.c
index a81ffdd16..3e2332077 100644
--- a/atomic/unix/s390.c
+++ b/atomic/unix/s390.c
@@ -129,4 +129,27 @@ APR_DECLARE(void*) apr_atomic_casptr(volatile void **mem, void *with, const void
     return prev;
 }
 
+APR_DECLARE(void*) apr_atomic_xchgptr(volatile void **mem, void *with)
+{
+    void *prev = (void *) *mem;
+#if APR_SIZEOF_VOIDP == 4
+    asm volatile ("loop_%=:\n"
+                  "	cs  %0,%2,%1\n"
+                  "	jl  loop_%=\n"
+                  : "+d" (prev), "=Q" (*mem)
+                  : "d" (with), "m" (*mem)
+                  : "cc", "memory");
+#elif APR_SIZEOF_VOIDP == 8
+    asm volatile ("loop_%=:\n"
+                  "	csg %0,%2,%1\n"
+                  "	jl  loop_%=\n"
+                  : "+d" (prev), "=Q" (*mem)
+                  : "d" (with), "m" (*mem)
+                  : "cc", "memory");
+#else
+#error APR_SIZEOF_VOIDP value not supported
+#endif
+    return prev;
+}
+
 #endif /* USE_ATOMICS_S390 */
diff --git a/atomic/unix/solaris.c b/atomic/unix/solaris.c
index f74a7ef2d..ba544522f 100644
--- a/atomic/unix/solaris.c
+++ b/atomic/unix/solaris.c
@@ -71,4 +71,9 @@ APR_DECLARE(void*) apr_atomic_casptr(volatile void **mem, void *with, const void
     return atomic_cas_ptr(mem, cmp, with);
 }
 
+APR_DECLARE(void*) apr_atomic_xchgptr(volatile void **mem, void *with)
+{
+    return atomic_swap_ptr(mem, with);
+}
+
 #endif /* USE_ATOMICS_SOLARIS */
diff --git a/atomic/win32/apr_atomic.c b/atomic/win32/apr_atomic.c
index e88f2e256..44e8ca2dd 100644
--- a/atomic/win32/apr_atomic.c
+++ b/atomic/win32/apr_atomic.c
@@ -38,6 +38,9 @@ typedef WINBASEAPI apr_uint32_t (WINAPI * apr_atomic_win32_ptr_val_val_fn)
 typedef WINBASEAPI void * (WINAPI * apr_atomic_win32_ptr_ptr_ptr_fn)
     (volatile void **, 
      void *, const void *);
+typedef WINBASEAPI void * (WINAPI * apr_atomic_win32_ptr_ptr_fn)
+    (volatile void **,
+     void *);
 
 APR_DECLARE(apr_uint32_t) apr_atomic_add32(volatile apr_uint32_t *mem, apr_uint32_t val)
 {
@@ -135,3 +138,13 @@ APR_DECLARE(apr_uint32_t) apr_atomic_xchg32(volatile apr_uint32_t *mem, apr_uint
     return ((apr_atomic_win32_ptr_val_fn)InterlockedExchange)(mem, val);
 #endif
 }
+
+APR_DECLARE(void*) apr_atomic_xchgptr(volatile void **mem, void *with)
+{
+#if (defined(_M_IA64) || defined(_M_AMD64) || defined(__MINGW32__)) && !defined(RC_INVOKED)
+    return InterlockedExchangePointer((void**)mem, with);
+#else
+    /* Too many VC6 users have stale win32 API files, stub this */
+    return ((apr_atomic_win32_ptr_ptr_fn)InterlockedExchangePointer)(mem, with);
+#endif
+}