Support for native and emulated atomic operations has been added.
authorMike Gorchak <lestat@i.com.ua>
Sun, 19 Jul 2009 08:04:59 +0000
changeset 3217 26ce0b98f2fb
parent 3216 48a80f2a7ff2
child 3218 81773a1eac83
Support for native and emulated atomic operations has been added.
configure.in
src/atomic/qnx/SDL_atomic.c
--- a/configure.in	Thu Jul 09 21:31:27 2009 +0000
+++ b/configure.in	Sun Jul 19 08:04:59 2009 +0000
@@ -2572,6 +2572,12 @@
             SOURCES="$SOURCES $srcdir/src/timer/unix/*.c"
             have_timers=yes
         fi
+        # Setup files for the atomic operations
+        if test x$enable_atomic = xyes; then
+                AC_DEFINE(SDL_ATOMIC_QNX)
+                SOURCES="$SOURCES $srcdir/src/atomic/qnx/*.c"
+                have_atomic=yes
+        fi
         # Set up dummy files for the joystick for now
         if test x$enable_joystick = xyes; then
             AC_DEFINE(SDL_JOYSTICK_DUMMY)
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/atomic/qnx/SDL_atomic.c	Sun Jul 19 08:04:59 2009 +0000
@@ -0,0 +1,882 @@
+/*
+    SDL - Simple DirectMedia Layer
+    Copyright (C) 1997-2009 Sam Lantinga
+
+    This library is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Lesser General Public
+    License as published by the Free Software Foundation; either
+    version 2.1 of the License, or (at your option) any later version.
+
+    This library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public
+    License along with this library; if not, write to the Free Software
+    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+
+    Sam Lantinga
+    slouken@libsdl.org
+*/
+
+#include "SDL_stdinc.h"
+#include "SDL_atomic.h"
+
+#include <atomic.h>
+
+/*
+  This file provides 8, 16, 32, and 64 bit atomic operations. If the
+  operations are provided by the native hardware and operating system
+  they are used. If they are not then the operations are emulated
+  using the SDL mutex operations. 
+ */
+
+/* 
+  First, detect whether the operations are supported and create
+  #defines that indicate that they do exist. The goal is to have all
+  the system dependent code in the top part of the file so that the
+  bottom can be use unchanged across all platforms.
+
+  Second, #define all the operations in each size class that are
+  supported. Doing this allows supported operations to be used along
+  side of emulated operations.
+*/
+
+/* 
+   Emmulated version.
+
+   Assume there is no support for atomic operations. All such
+   operations are implemented using SDL mutex operations.
+ */
+
+#ifdef EMULATED_ATOMIC_OPERATIONS
+#undef EMULATED_ATOMIC_OPERATIONS
+#endif
+
+#ifdef EMULATED_ATOMIC_OPERATIONS
+#define HAVE_ALL_8_BIT_OPS
+
+#define nativeExchange8(ptr, value)			()
+#define nativeCompareThenSet8(ptr, oldvalue, newvalue) 	()
+#define nativeTestThenSet8(ptr)    	     		()
+#define nativeClear8(ptr)				()
+#define nativeFetchThenIncrement8(ptr)   		()
+#define nativeFetchThenDecrement8(ptr) 			()
+#define nativeFetchThenAdd8(ptr, value) 		()
+#define nativeFetchThenSubtract8(ptr, value) 		()
+#define nativeIncrementThenFetch8(ptr) 			()
+#define nativeDecrementThenFetch8(ptr) 			()
+#define nativeAddThenFetch8(ptr, value) 		()
+#define nativeSubtractThenFetch8(ptr, value) 		()
+#endif
+
+#ifdef EMULATED_ATOMIC_OPERATIONS
+#define HAVE_ALL_16_BIT_OPS
+
+#define nativeExchange16(ptr, value)			()
+#define nativeCompareThenSet16(ptr, oldvalue, newvalue) ()
+#define nativeTestThenSet16(ptr)    	     		()
+#define nativeClear16(ptr)				()
+#define nativeFetchThenIncrement16(ptr)   		()
+#define nativeFetchThenDecrement16(ptr) 		()
+#define nativeFetchThenAdd16(ptr, value) 		()
+#define nativeFetchThenSubtract16(ptr, value) 		()
+#define nativeIncrementThenFetch16(ptr) 		()
+#define nativeDecrementThenFetch16(ptr) 		()
+#define nativeAddThenFetch16(ptr, value) 		()
+#define nativeSubtractThenFetch16(ptr, value) 		()
+#endif
+
+#ifdef EMULATED_ATOMIC_OPERATIONS
+#define HAVE_ALL_64_BIT_OPS
+
+#define nativeExchange64(ptr, value)			()
+#define nativeCompareThenSet64(ptr, oldvalue, newvalue) ()
+#define nativeTestThenSet64(ptr)    	     		()
+#define nativeClear64(ptr)				()
+#define nativeFetchThenIncrement64(ptr)   		()
+#define nativeFetchThenDecrement64(ptr) 		()
+#define nativeFetchThenAdd64(ptr, value) 		()
+#define nativeFetchThenSubtract64(ptr, value) 		()
+#define nativeIncrementThenFetch64(ptr) 		()
+#define nativeDecrementThenFetch64(ptr) 		()
+#define nativeAddThenFetch64(ptr, value) 		()
+#define nativeSubtractThenFetch64(ptr, value) 		()
+#endif
+
+/*
+If any of the operations are not provided then we must emulate some of
+them.
+ */
+
+#if !defined(HAVE_ALL_8_BIT_OPS) || !defined(HAVE_ALL_16_BIT_OPS) || !defined(HAVE_ALL_64_BIT_OPS)
+
+#include "SDL_mutex.h"
+#include "SDL_error.h"
+
+static SDL_mutex * lock = NULL;
+
+static __inline__ void
+privateWaitLock()
+{
+   if(NULL == lock)
+   {
+      lock = SDL_CreateMutex();
+      if (NULL == lock)
+      {
+	 SDL_SetError("SDL_atomic.c: can't create a mutex");
+	 return;
+      }
+   }
+
+   if (-1 == SDL_LockMutex(lock))
+   {
+      SDL_SetError("SDL_atomic.c: can't lock mutex");
+   }
+}
+
+static __inline__ void
+privateUnlock()
+{
+   if (-1 == SDL_UnlockMutex(lock))
+   {
+      SDL_SetError("SDL_atomic.c: can't unlock mutex");
+   }
+}
+
+#endif
+
+/* 8 bit atomic operations */
+
+Uint8
+SDL_AtomicExchange8(volatile Uint8 * ptr, Uint8 value)
+{
+#ifdef nativeExchange8
+   return nativeExchange8(ptr, value);
+#else
+   Uint8 tmp = 0;
+
+   privateWaitLock();
+   tmp = *ptr;
+   *ptr = value;
+   privateUnlock();
+
+   return tmp;
+#endif
+}
+
+SDL_bool
+SDL_AtomicCompareThenSet8(volatile Uint8 * ptr, Uint8 oldvalue, Uint8 newvalue)
+{
+#ifdef nativeCompareThenSet8
+   return (SDL_bool)nativeCompareThenSet8(ptr, oldvalue, newvalue);
+#else
+   SDL_bool result = SDL_FALSE;
+
+   privateWaitLock();
+   result = (*ptr == oldvalue);
+   if (result)
+   {
+      *ptr = newvalue;
+   }
+   privateUnlock();
+
+   return result;
+#endif
+}
+
+SDL_bool
+SDL_AtomicTestThenSet8(volatile Uint8 * ptr)
+{
+#ifdef nativeTestThenSet8
+   return (SDL_bool)nativeTestThenSet8(ptr);
+#else
+   SDL_bool result = SDL_FALSE;
+
+   privateWaitLock();
+   result = (*ptr == 0);
+   if (result)
+   {
+      *ptr = 1;
+   }
+   privateUnlock();
+
+   return result;
+#endif
+}
+
+void
+SDL_AtomicClear8(volatile Uint8 * ptr)
+{
+#ifdef nativeClear8
+   nativeClear8(ptr);
+#else
+   privateWaitLock();
+   *ptr = 0;
+   privateUnlock();
+
+   return;
+#endif
+}
+
+Uint8
+SDL_AtomicFetchThenIncrement8(volatile Uint8 * ptr)
+{
+#ifdef nativeFetchThenIncrement8
+   return nativeFetchThenIncrement8(ptr);
+#else
+   Uint8 tmp = 0;
+
+   privateWaitLock();
+   tmp = *ptr;
+   (*ptr)+= 1;
+   privateUnlock();
+
+   return tmp;
+#endif
+}
+
+Uint8
+SDL_AtomicFetchThenDecrement8(volatile Uint8 * ptr)
+{
+#ifdef nativeFetchThenDecrement8
+   return nativeFetchThenDecrement8(ptr);
+#else
+   Uint8 tmp = 0;
+
+   privateWaitLock();
+   tmp = *ptr;
+   (*ptr) -= 1;
+   privateUnlock();
+
+   return tmp;
+#endif
+}
+
+Uint8
+SDL_AtomicFetchThenAdd8(volatile Uint8 * ptr, Uint8 value)
+{
+#ifdef nativeFetchThenAdd8
+   return nativeFetchThenAdd8(ptr, value);
+#else
+   Uint8 tmp = 0;
+
+   privateWaitLock();
+   tmp = *ptr;
+   (*ptr)+= value;
+   privateUnlock();
+
+   return tmp;
+#endif
+}
+
+Uint8
+SDL_AtomicFetchThenSubtract8(volatile Uint8 * ptr, Uint8 value)
+{
+#ifdef nativeFetchThenSubtract8
+   return nativeFetchThenSubtract8(ptr, value);
+#else
+   Uint8 tmp = 0;
+
+   privateWaitLock();
+   tmp = *ptr;
+   (*ptr)-= value;
+   privateUnlock();
+
+   return tmp;
+#endif
+}
+
+Uint8
+SDL_AtomicIncrementThenFetch8(volatile Uint8 * ptr)
+{
+#ifdef nativeIncrementThenFetch8
+   return nativeIncrementThenFetch8(ptr);
+#else
+   Uint8 tmp = 0;
+
+   privateWaitLock();
+   (*ptr)+= 1;
+   tmp = *ptr;
+   privateUnlock();
+
+   return tmp;
+#endif
+}
+
+Uint8
+SDL_AtomicDecrementThenFetch8(volatile Uint8 * ptr)
+{
+#ifdef nativeDecrementThenFetch8
+   return nativeDecrementThenFetch8(ptr);
+#else
+   Uint8 tmp = 0;
+
+   privateWaitLock();
+   (*ptr)-= 1;
+   tmp = *ptr;
+   privateUnlock();
+
+   return tmp;
+#endif
+}
+
+Uint8
+SDL_AtomicAddThenFetch8(volatile Uint8 * ptr, Uint8 value)
+{
+#ifdef nativeAddThenFetch8
+   return nativeAddThenFetch8(ptr, value);
+#else
+   Uint8 tmp = 0;
+
+   privateWaitLock();
+   (*ptr)+= value;
+   tmp = *ptr;
+   privateUnlock();
+
+   return tmp;
+#endif
+}
+
+Uint8
+SDL_AtomicSubtractThenFetch8(volatile Uint8 * ptr, Uint8 value)
+{
+#ifdef nativeSubtractThenFetch8
+   return nativeSubtractThenFetch8(ptr, value);
+#else
+   Uint8 tmp = 0;
+
+   privateWaitLock();
+   (*ptr)-= value;
+   tmp = *ptr;
+   privateUnlock();
+
+   return tmp;
+#endif
+}
+
+/* 16 bit atomic operations */
+
+Uint16
+SDL_AtomicExchange16(volatile Uint16 * ptr, Uint16 value)
+{
+#ifdef nativeExchange16
+   return nativeExchange16(ptr, value);
+#else
+   Uint16 tmp = 0;
+
+   privateWaitLock();
+   tmp = *ptr;
+   *ptr = value;
+   privateUnlock();
+
+   return tmp;
+#endif
+}
+
+SDL_bool
+SDL_AtomicCompareThenSet16(volatile Uint16 * ptr, Uint16 oldvalue, Uint16 newvalue)
+{
+#ifdef nativeCompareThenSet16
+   return (SDL_bool)nativeCompareThenSet16(ptr, oldvalue, newvalue);
+#else
+   SDL_bool result = SDL_FALSE;
+
+   privateWaitLock();
+   result = (*ptr == oldvalue);
+   if (result)
+   {
+      *ptr = newvalue;
+   }
+   privateUnlock();
+
+   return result;
+#endif
+}
+
+SDL_bool
+SDL_AtomicTestThenSet16(volatile Uint16 * ptr)
+{
+#ifdef nativeTestThenSet16
+   return (SDL_bool)nativeTestThenSet16(ptr);
+#else
+   SDL_bool result = SDL_FALSE;
+
+   privateWaitLock();
+   result = (*ptr == 0);
+   if (result)
+   {
+      *ptr = 1;
+   }
+   privateUnlock();
+
+   return result;
+#endif
+}
+
+void
+SDL_AtomicClear16(volatile Uint16 * ptr)
+{
+#ifdef nativeClear16
+   nativeClear16(ptr);
+#else
+   privateWaitLock();
+   *ptr = 0;
+   privateUnlock();
+
+   return;
+#endif
+}
+
+Uint16
+SDL_AtomicFetchThenIncrement16(volatile Uint16 * ptr)
+{
+#ifdef nativeFetchThenIncrement16
+   return nativeFetchThenIncrement16(ptr);
+#else
+   Uint16 tmp = 0;
+
+   privateWaitLock();
+   tmp = *ptr;
+   (*ptr)+= 1;
+   privateUnlock();
+
+   return tmp;
+#endif
+}
+
+Uint16
+SDL_AtomicFetchThenDecrement16(volatile Uint16 * ptr)
+{
+#ifdef nativeFetchThenDecrement16
+   return nativeFetchThenDecrement16(ptr);
+#else
+   Uint16 tmp = 0;
+
+   privateWaitLock();
+   tmp = *ptr;
+   (*ptr) -= 1;
+   privateUnlock();
+
+   return tmp;
+#endif
+}
+
+Uint16
+SDL_AtomicFetchThenAdd16(volatile Uint16 * ptr, Uint16 value)
+{
+#ifdef nativeFetchThenAdd16
+   return nativeFetchThenAdd16(ptr, value);
+#else
+   Uint16 tmp = 0;
+
+   privateWaitLock();
+   tmp = *ptr;
+   (*ptr)+= value;
+   privateUnlock();
+
+   return tmp;
+#endif
+}
+
+Uint16
+SDL_AtomicFetchThenSubtract16(volatile Uint16 * ptr, Uint16 value)
+{
+#ifdef nativeFetchThenSubtract16
+   return nativeFetchThenSubtract16(ptr, value);
+#else
+   Uint16 tmp = 0;
+
+   privateWaitLock();
+   tmp = *ptr;
+   (*ptr)-= value;
+   privateUnlock();
+
+   return tmp;
+#endif
+}
+
+Uint16
+SDL_AtomicIncrementThenFetch16(volatile Uint16 * ptr)
+{
+#ifdef nativeIncrementThenFetch16
+   return nativeIncrementThenFetch16(ptr);
+#else
+   Uint16 tmp = 0;
+
+   privateWaitLock();
+   (*ptr)+= 1;
+   tmp = *ptr;
+   privateUnlock();
+
+   return tmp;
+#endif
+}
+
+Uint16
+SDL_AtomicDecrementThenFetch16(volatile Uint16 * ptr)
+{
+#ifdef nativeDecrementThenFetch16
+   return nativeDecrementThenFetch16(ptr);
+#else
+   Uint16 tmp = 0;
+
+   privateWaitLock();
+   (*ptr)-= 1;
+   tmp = *ptr;
+   privateUnlock();
+
+   return tmp;
+#endif
+}
+
+Uint16
+SDL_AtomicAddThenFetch16(volatile Uint16 * ptr, Uint16 value)
+{
+#ifdef nativeAddThenFetch16
+   return nativeAddThenFetch16(ptr, value);
+#else
+   Uint16 tmp = 0;
+
+   privateWaitLock();
+   (*ptr)+= value;
+   tmp = *ptr;
+   privateUnlock();
+
+   return tmp;
+#endif
+}
+
+Uint16
+SDL_AtomicSubtractThenFetch16(volatile Uint16 * ptr, Uint16 value)
+{
+#ifdef nativeSubtractThenFetch16
+   return nativeSubtractThenFetch16(ptr, value);
+#else
+   Uint16 tmp = 0;
+
+   privateWaitLock();
+   (*ptr)-= value;
+   tmp = *ptr;
+   privateUnlock();
+
+   return tmp;
+#endif
+}
+
+/* 64 bit atomic operations */
+#ifdef SDL_HAS_64BIT_TYPE
+
+Uint64
+SDL_AtomicExchange64(volatile Uint64 * ptr, Uint64 value)
+{
+#ifdef nativeExchange64
+   return nativeExchange64(ptr, value);
+#else
+   Uint64 tmp = 0;
+
+   privateWaitLock();
+   tmp = *ptr;
+   *ptr = value;
+   privateUnlock();
+
+   return tmp;
+#endif
+}
+
+SDL_bool
+SDL_AtomicCompareThenSet64(volatile Uint64 * ptr, Uint64 oldvalue, Uint64 newvalue)
+{
+#ifdef nativeCompareThenSet64
+   return (SDL_bool)nativeCompareThenSet64(ptr, oldvalue, newvalue);
+#else
+   SDL_bool result = SDL_FALSE;
+
+   privateWaitLock();
+   result = (*ptr == oldvalue);
+   if (result)
+   {
+      *ptr = newvalue;
+   }
+   privateUnlock();
+
+   return result;
+#endif
+}
+
+SDL_bool
+SDL_AtomicTestThenSet64(volatile Uint64 * ptr)
+{
+#ifdef nativeTestThenSet64
+   return (SDL_bool)nativeTestThenSet64(ptr);
+#else
+   SDL_bool result = SDL_FALSE;
+
+   privateWaitLock();
+   result = (*ptr == 0);
+   if (result)
+   {
+      *ptr = 1;
+   }
+   privateUnlock();
+
+   return result;
+#endif
+}
+
+void
+SDL_AtomicClear64(volatile Uint64 * ptr)
+{
+#ifdef nativeClear64
+   nativeClear64(ptr);
+#else
+   privateWaitLock();
+   *ptr = 0;
+   privateUnlock();
+
+   return;
+#endif
+}
+
+Uint64
+SDL_AtomicFetchThenIncrement64(volatile Uint64 * ptr)
+{
+#ifdef nativeFetchThenIncrement64
+   return nativeFetchThenIncrement64(ptr);
+#else
+   Uint64 tmp = 0;
+
+   privateWaitLock();
+   tmp = *ptr;
+   (*ptr)+= 1;
+   privateUnlock();
+
+   return tmp;
+#endif
+}
+
+Uint64
+SDL_AtomicFetchThenDecrement64(volatile Uint64 * ptr)
+{
+#ifdef nativeFetchThenDecrement64
+   return nativeFetchThenDecrement64(ptr);
+#else
+   Uint64 tmp = 0;
+
+   privateWaitLock();
+   tmp = *ptr;
+   (*ptr) -= 1;
+   privateUnlock();
+
+   return tmp;
+#endif
+}
+
+Uint64
+SDL_AtomicFetchThenAdd64(volatile Uint64 * ptr, Uint64 value)
+{
+#ifdef nativeFetchThenAdd64
+   return nativeFetchThenAdd64(ptr, value);
+#else
+   Uint64 tmp = 0;
+
+   privateWaitLock();
+   tmp = *ptr;
+   (*ptr)+= value;
+   privateUnlock();
+
+   return tmp;
+#endif
+}
+
+Uint64
+SDL_AtomicFetchThenSubtract64(volatile Uint64 * ptr, Uint64 value)
+{
+#ifdef nativeFetchThenSubtract64
+   return nativeFetchThenSubtract64(ptr, value);
+#else
+   Uint64 tmp = 0;
+
+   privateWaitLock();
+   tmp = *ptr;
+   (*ptr)-= value;
+   privateUnlock();
+
+   return tmp;
+#endif
+}
+
+Uint64
+SDL_AtomicIncrementThenFetch64(volatile Uint64 * ptr)
+{
+#ifdef nativeIncrementThenFetch64
+   return nativeIncrementThenFetch64(ptr);
+#else
+   Uint64 tmp = 0;
+
+   privateWaitLock();
+   (*ptr)+= 1;
+   tmp = *ptr;
+   privateUnlock();
+
+   return tmp;
+#endif
+}
+
+Uint64
+SDL_AtomicDecrementThenFetch64(volatile Uint64 * ptr)
+{
+#ifdef nativeDecrementThenFetch64
+   return nativeDecrementThenFetch64(ptr);
+#else
+   Uint64 tmp = 0;
+
+   privateWaitLock();
+   (*ptr)-= 1;
+   tmp = *ptr;
+   privateUnlock();
+
+   return tmp;
+#endif
+}
+
+Uint64
+SDL_AtomicAddThenFetch64(volatile Uint64 * ptr, Uint64 value)
+{
+#ifdef nativeAddThenFetch64
+   return nativeAddThenFetch64(ptr, value);
+#else
+   Uint64 tmp = 0;
+
+   privateWaitLock();
+   (*ptr)+= value;
+   tmp = *ptr;
+   privateUnlock();
+
+   return tmp;
+#endif
+}
+
+Uint64
+SDL_AtomicSubtractThenFetch64(volatile Uint64 * ptr, Uint64 value)
+{
+#ifdef nativeSubtractThenFetch64
+   return nativeSubtractThenFetch64(ptr, value);
+#else
+   Uint64 tmp = 0;
+
+   privateWaitLock();
+   (*ptr)-= value;
+   tmp = *ptr;
+   privateUnlock();
+
+   return tmp;
+#endif
+}
+#endif
+
+/* QNX native 32 bit atomic operations */
+
+Uint32
+SDL_AtomicExchange32(volatile Uint32 * ptr, Uint32 value)
+{
+   Uint32 tmp = 0;
+
+   privateWaitLock();
+   tmp = *ptr;
+   *ptr = value;
+   privateUnlock();
+
+   return tmp;
+}
+
+SDL_bool
+SDL_AtomicCompareThenSet32(volatile Uint32 * ptr, Uint32 oldvalue, Uint32 newvalue)
+{
+   SDL_bool result = SDL_FALSE;
+
+   privateWaitLock();
+   result = (*ptr == oldvalue);
+   if (result)
+   {
+      *ptr = newvalue;
+   }
+   privateUnlock();
+
+   return result;
+}
+
+SDL_bool
+SDL_AtomicTestThenSet32(volatile Uint32 * ptr)
+{
+   SDL_bool result = SDL_FALSE;
+
+   privateWaitLock();
+   result = (*ptr == 0);
+   if (result)
+   {
+      *ptr = 1;
+   }
+   privateUnlock();
+
+   return result;
+}
+
+void
+SDL_AtomicClear32(volatile Uint32 * ptr)
+{
+   atomic_clr(ptr, 0xFFFFFFFF);
+}
+
+Uint32
+SDL_AtomicFetchThenIncrement32(volatile Uint32 * ptr)
+{
+   return atomic_add_value(ptr, 0x00000001);
+}
+
+Uint32
+SDL_AtomicFetchThenDecrement32(volatile Uint32 * ptr)
+{
+   return atomic_sub_value(ptr, 0x00000001);
+}
+
+Uint32
+SDL_AtomicFetchThenAdd32(volatile Uint32 * ptr, Uint32 value)
+{
+   return atomic_add_value(ptr, value);
+}
+
+Uint32
+SDL_AtomicFetchThenSubtract32(volatile Uint32 * ptr, Uint32 value)
+{
+   return atomic_sub_value(ptr, value);
+}
+
+Uint32
+SDL_AtomicIncrementThenFetch32(volatile Uint32 * ptr)
+{
+   atomic_add(ptr, 0x00000001);
+   return atomic_add_value(ptr, 0x00000000);
+}
+
+Uint32
+SDL_AtomicDecrementThenFetch32(volatile Uint32 * ptr)
+{
+   atomic_sub(ptr, 0x00000001);
+   return atomic_sub_value(ptr, 0x00000000);
+}
+
+Uint32
+SDL_AtomicAddThenFetch32(volatile Uint32 * ptr, Uint32 value)
+{
+   atomic_add(ptr, value);
+   return atomic_add_value(ptr, 0x00000000);
+}
+
+Uint32
+SDL_AtomicSubtractThenFetch32(volatile Uint32 * ptr, Uint32 value)
+{
+   atomic_sub(ptr, value);
+   return atomic_sub_value(ptr, 0x00000000);
+}