Merge pull request #1110 from patrickbabb/master

Updates to target arm64-v8a Android devices

Boost/boost/smart_ptr/detail/spinlock_gcc_arm.hpp

@@ -29,11 +29,30 @@ public:
     {
         int r;
 
+        #if defined(__ARM_FEATURE_LSE)
+        // Use LSE atomic instructions if supported
+        #pragma message("LSE feature detected") // This will print a message in your build logs
         __asm__ __volatile__(
-            "swp %0, %1, [%2]":
+            "ldaxr %0, [%1];"   // Load-Exclusive instruction
-            "=&r"( r ): // outputs
+            "cbnz %0, 1f;"       // If the value is non-zero, the lock is already acquired
-            "r"( 1 ), "r"( &v_ ): // inputs
+            "stlxr %w0, %2, [%1];" // Store-Exclusive instruction
-            "memory", "cc" );
+            "cbnz %w0, 1f;"      // If the store failed, retry
+            "mov %0, #0;"        // Success, zero indicates lock acquired
+            "1:"
+            : "=&r"(r)
+            : "r"(&v_), "r"(1)
+            : "memory", "cc"
+        );
+        #else
+        // Fallback for systems that don't support LSE
+        #pragma message("LSE feature not detected") // This will print a message in your build logs if LSE is not detected
+        __asm__ __volatile__(
+            "swp %0, %1, [%2];"  // Swap instruction (used as a fallback)
+            : "=&r"(r)            // output constraint
+            : "r"(1), "r"(&v_)    // input constraints
+            : "memory", "cc"      // clobbered registers
+        );
+        #endif
 
         return r == 0;
     }

JGE/Dependencies/SDL/src/atomic/SDL_spinlock.c

@@ -14,10 +14,11 @@
      claim that you wrote the original software. If you use this software
      in a product, an acknowledgment in the product documentation would be
      appreciated but is not required.
-  2. Altered source versions must be plainly marked as such, and must not be
+  2. Altered source versions must be plainly marked as such, and must not
-     misrepresented as being the original software.
+     be misrepresented as being the original software.
   3. This notice may not be removed or altered from any source distribution.
 */
+
 #include "SDL_stdinc.h"
 
 #include "SDL_atomic.h"
@@ -30,8 +31,7 @@
 #endif
 
 /* This function is where all the magic happens... */
-SDL_bool
+SDL_bool SDL_AtomicTryLock(SDL_SpinLock *lock)
-SDL_AtomicTryLock(SDL_SpinLock *lock)
 {
 #if SDL_ATOMIC_DISABLED
     /* Terrible terrible damage */
@@ -85,13 +85,27 @@ SDL_AtomicTryLock(SDL_SpinLock *lock)
     return (result == 0);
 
 #else
-    /* Need CPU instructions for spinlock here! */
+    /* Fallback implementation using a standard mutex */
-    __need_spinlock_implementation__
+    /* You can use SDL_mutex as a fallback if no atomic instructions are available */
+    static SDL_mutex *mutex;
+    if (!mutex) {
+        mutex = SDL_CreateMutex();
+    }
+
+    SDL_mutexP(mutex);
+    if (*lock == 0) {
+        *lock = 1;
+        SDL_mutexV(mutex);
+        return SDL_TRUE;
+    } else {
+        SDL_mutexV(mutex);
+        return SDL_FALSE;
+    }
+
 #endif
 }
 
-void
+void SDL_AtomicLock(SDL_SpinLock *lock)
-SDL_AtomicLock(SDL_SpinLock *lock)
 {
     /* FIXME: Should we have an eventual timeout? */
     while (!SDL_AtomicTryLock(lock)) {
@@ -99,8 +113,7 @@ SDL_AtomicLock(SDL_SpinLock *lock)
     }
 }
 
-void
+void SDL_AtomicUnlock(SDL_SpinLock *lock)
-SDL_AtomicUnlock(SDL_SpinLock *lock)
 {
 #if defined(_MSC_VER)
     _ReadWriteBarrier();

projects/mtg/Android/jni/Application.mk

@@ -1,6 +1,9 @@
 APP_PROJECT_PATH := $(call my-dir)/..
 APP_CPPFLAGS += -frtti -fexceptions
-APP_ABI := armeabi-v7a
+APP_ABI := arm64-v8a
+APP_PLATFORM := android-21
+APP_CFLAGS += -march=armv8.1-a
+APP_CPPFLAGS += -D__ARM_FEATURE_LSE=1
 #APP_ABI := x86 # mainly for emulators
 APP_STL := c++_static
 APP_MODULES := libpng libjpeg main SDL