initial commit, 4.5 stable

thirdparty/sdl/atomic/SDL_spinlock.c

@@ -0,0 +1,203 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2025 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     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
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+#include "SDL_internal.h"
+
+#if defined(SDL_PLATFORM_WINDOWS)
+#include "../core/windows/SDL_windows.h"
+#endif
+
+#if !defined(HAVE_GCC_ATOMICS) && defined(SDL_PLATFORM_SOLARIS)
+#include <atomic.h>
+#endif
+
+#if !defined(HAVE_GCC_ATOMICS) && defined(SDL_PLATFORM_RISCOS)
+#include <unixlib/local.h>
+#endif
+
+#if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64))
+#include <xmmintrin.h>
+#endif
+
+#ifdef PS2
+#include <kernel.h>
+#endif
+
+#if !defined(HAVE_GCC_ATOMICS) && defined(SDL_PLATFORM_MACOS)
+#include <libkern/OSAtomic.h>
+#endif
+
+/* *INDENT-OFF* */ // clang-format off
+#if defined(__WATCOMC__) && defined(__386__)
+SDL_COMPILE_TIME_ASSERT(locksize, 4==sizeof(SDL_SpinLock));
+extern __inline int _SDL_xchg_watcom(volatile int *a, int v);
+#pragma aux _SDL_xchg_watcom = \
+  "lock xchg [ecx], eax" \
+  parm [ecx] [eax] \
+  value [eax] \
+  modify exact [eax];
+#endif // __WATCOMC__ && __386__
+/* *INDENT-ON* */ // clang-format on
+
+// This function is where all the magic happens...
+bool SDL_TryLockSpinlock(SDL_SpinLock *lock)
+{
+#if defined(HAVE_GCC_ATOMICS) || defined(HAVE_GCC_SYNC_LOCK_TEST_AND_SET)
+    return __sync_lock_test_and_set(lock, 1) == 0;
+
+#elif defined(_MSC_VER) && (defined(_M_ARM) || defined(_M_ARM64))
+    return _InterlockedExchange_acq(lock, 1) == 0;
+
+#elif defined(_MSC_VER)
+    SDL_COMPILE_TIME_ASSERT(locksize, sizeof(*lock) == sizeof(long));
+    return InterlockedExchange((long *)lock, 1) == 0;
+
+#elif defined(__WATCOMC__) && defined(__386__)
+    return _SDL_xchg_watcom(lock, 1) == 0;
+
+#elif defined(__GNUC__) && defined(__arm__) &&               \
+    (defined(__ARM_ARCH_3__) || defined(__ARM_ARCH_3M__) ||  \
+     defined(__ARM_ARCH_4__) || defined(__ARM_ARCH_4T__) ||  \
+     defined(__ARM_ARCH_5__) || defined(__ARM_ARCH_5TE__) || \
+     defined(__ARM_ARCH_5TEJ__))
+    int result;
+
+#ifdef SDL_PLATFORM_RISCOS
+    if (__cpucap_have_rex()) {
+        __asm__ __volatile__(
+            "ldrex %0, [%2]\nteq   %0, #0\nstrexeq %0, %1, [%2]"
+            : "=&r"(result)
+            : "r"(1), "r"(lock)
+            : "cc", "memory");
+        return result == 0;
+    }
+#endif
+
+    __asm__ __volatile__(
+        "swp %0, %1, [%2]\n"
+        : "=&r,&r"(result)
+        : "r,0"(1), "r,r"(lock)
+        : "memory");
+    return result == 0;
+
+#elif defined(__GNUC__) && defined(__arm__)
+    int result;
+    __asm__ __volatile__(
+        "ldrex %0, [%2]\nteq   %0, #0\nstrexeq %0, %1, [%2]"
+        : "=&r"(result)
+        : "r"(1), "r"(lock)
+        : "cc", "memory");
+    return result == 0;
+
+#elif defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
+    int result;
+    __asm__ __volatile__(
+        "lock ; xchgl %0, (%1)\n"
+        : "=r"(result)
+        : "r"(lock), "0"(1)
+        : "cc", "memory");
+    return result == 0;
+
+#elif defined(SDL_PLATFORM_MACOS) || defined(SDL_PLATFORM_IOS) || defined(SDL_PLATFORM_TVOS)
+    // Maybe used for PowerPC, but the Intel asm or gcc atomics are favored.
+    return OSAtomicCompareAndSwap32Barrier(0, 1, lock);
+
+#elif defined(SDL_PLATFORM_SOLARIS) && defined(_LP64)
+    // Used for Solaris with non-gcc compilers.
+    return ((int)atomic_cas_64((volatile uint64_t *)lock, 0, 1) == 0);
+
+#elif defined(SDL_PLATFORM_SOLARIS) && !defined(_LP64)
+    // Used for Solaris with non-gcc compilers.
+    return ((int)atomic_cas_32((volatile uint32_t *)lock, 0, 1) == 0);
+#elif defined(PS2)
+    uint32_t oldintr;
+    bool res = false;
+    // disable interruption
+    oldintr = DIntr();
+
+    if (*lock == 0) {
+        *lock = 1;
+        res = true;
+    }
+    // enable interruption
+    if (oldintr) {
+        EIntr();
+    }
+    return res;
+#else
+    // Terrible terrible damage
+    static SDL_Mutex *_spinlock_mutex;
+
+    if (!_spinlock_mutex) {
+        // Race condition on first lock...
+        _spinlock_mutex = SDL_CreateMutex();
+    }
+    SDL_LockMutex(_spinlock_mutex);
+    if (*lock == 0) {
+        *lock = 1;
+        SDL_UnlockMutex(_spinlock_mutex);
+        return true;
+    } else {
+        SDL_UnlockMutex(_spinlock_mutex);
+        return false;
+    }
+#endif
+}
+
+void SDL_LockSpinlock(SDL_SpinLock *lock)
+{
+    int iterations = 0;
+    // FIXME: Should we have an eventual timeout?
+    while (!SDL_TryLockSpinlock(lock)) {
+        if (iterations < 32) {
+            iterations++;
+            SDL_CPUPauseInstruction();
+        } else {
+            // !!! FIXME: this doesn't definitely give up the current timeslice, it does different things on various platforms.
+            SDL_Delay(0);
+        }
+    }
+}
+
+void SDL_UnlockSpinlock(SDL_SpinLock *lock)
+{
+#if defined(HAVE_GCC_ATOMICS) || defined(HAVE_GCC_SYNC_LOCK_TEST_AND_SET)
+    __sync_lock_release(lock);
+
+#elif defined(_MSC_VER) && (defined(_M_ARM) || defined(_M_ARM64))
+    _InterlockedExchange_rel(lock, 0);
+
+#elif defined(_MSC_VER)
+    _ReadWriteBarrier();
+    *lock = 0;
+
+#elif defined(__WATCOMC__) && defined(__386__)
+    SDL_CompilerBarrier();
+    *lock = 0;
+
+#elif defined(SDL_PLATFORM_SOLARIS)
+    // Used for Solaris when not using gcc.
+    *lock = 0;
+    membar_producer();
+
+#else
+    *lock = 0;
+#endif
+}