diff options
Diffstat (limited to 'contrib/SDL-3.2.8/include/SDL3/SDL_atomic.h')
| -rw-r--r-- | contrib/SDL-3.2.8/include/SDL3/SDL_atomic.h | 664 |
1 files changed, 664 insertions, 0 deletions
diff --git a/contrib/SDL-3.2.8/include/SDL3/SDL_atomic.h b/contrib/SDL-3.2.8/include/SDL3/SDL_atomic.h new file mode 100644 index 0000000..78b5e0f --- /dev/null +++ b/contrib/SDL-3.2.8/include/SDL3/SDL_atomic.h | |||
| @@ -0,0 +1,664 @@ | |||
| 1 | /* | ||
| 2 | Simple DirectMedia Layer | ||
| 3 | Copyright (C) 1997-2025 Sam Lantinga <slouken@libsdl.org> | ||
| 4 | |||
| 5 | This software is provided 'as-is', without any express or implied | ||
| 6 | warranty. In no event will the authors be held liable for any damages | ||
| 7 | arising from the use of this software. | ||
| 8 | |||
| 9 | Permission is granted to anyone to use this software for any purpose, | ||
| 10 | including commercial applications, and to alter it and redistribute it | ||
| 11 | freely, subject to the following restrictions: | ||
| 12 | |||
| 13 | 1. The origin of this software must not be misrepresented; you must not | ||
| 14 | claim that you wrote the original software. If you use this software | ||
| 15 | in a product, an acknowledgment in the product documentation would be | ||
| 16 | appreciated but is not required. | ||
| 17 | 2. Altered source versions must be plainly marked as such, and must not be | ||
| 18 | misrepresented as being the original software. | ||
| 19 | 3. This notice may not be removed or altered from any source distribution. | ||
| 20 | */ | ||
| 21 | |||
| 22 | /** | ||
| 23 | * # CategoryAtomic | ||
| 24 | * | ||
| 25 | * Atomic operations. | ||
| 26 | * | ||
| 27 | * IMPORTANT: If you are not an expert in concurrent lockless programming, you | ||
| 28 | * should not be using any functions in this file. You should be protecting | ||
| 29 | * your data structures with full mutexes instead. | ||
| 30 | * | ||
| 31 | * ***Seriously, here be dragons!*** | ||
| 32 | * | ||
| 33 | * You can find out a little more about lockless programming and the subtle | ||
| 34 | * issues that can arise here: | ||
| 35 | * https://learn.microsoft.com/en-us/windows/win32/dxtecharts/lockless-programming | ||
| 36 | * | ||
| 37 | * There's also lots of good information here: | ||
| 38 | * | ||
| 39 | * - https://www.1024cores.net/home/lock-free-algorithms | ||
| 40 | * - https://preshing.com/ | ||
| 41 | * | ||
| 42 | * These operations may or may not actually be implemented using processor | ||
| 43 | * specific atomic operations. When possible they are implemented as true | ||
| 44 | * processor specific atomic operations. When that is not possible the are | ||
| 45 | * implemented using locks that *do* use the available atomic operations. | ||
| 46 | * | ||
| 47 | * All of the atomic operations that modify memory are full memory barriers. | ||
| 48 | */ | ||
| 49 | |||
| 50 | #ifndef SDL_atomic_h_ | ||
| 51 | #define SDL_atomic_h_ | ||
| 52 | |||
| 53 | #include <SDL3/SDL_stdinc.h> | ||
| 54 | #include <SDL3/SDL_platform_defines.h> | ||
| 55 | |||
| 56 | #include <SDL3/SDL_begin_code.h> | ||
| 57 | |||
| 58 | /* Set up for C function definitions, even when using C++ */ | ||
| 59 | #ifdef __cplusplus | ||
| 60 | extern "C" { | ||
| 61 | #endif | ||
| 62 | |||
| 63 | /** | ||
| 64 | * An atomic spinlock. | ||
| 65 | * | ||
| 66 | * The atomic locks are efficient spinlocks using CPU instructions, but are | ||
| 67 | * vulnerable to starvation and can spin forever if a thread holding a lock | ||
| 68 | * has been terminated. For this reason you should minimize the code executed | ||
| 69 | * inside an atomic lock and never do expensive things like API or system | ||
| 70 | * calls while holding them. | ||
| 71 | * | ||
| 72 | * They are also vulnerable to starvation if the thread holding the lock is | ||
| 73 | * lower priority than other threads and doesn't get scheduled. In general you | ||
| 74 | * should use mutexes instead, since they have better performance and | ||
| 75 | * contention behavior. | ||
| 76 | * | ||
| 77 | * The atomic locks are not safe to lock recursively. | ||
| 78 | * | ||
| 79 | * Porting Note: The spin lock functions and type are required and can not be | ||
| 80 | * emulated because they are used in the atomic emulation code. | ||
| 81 | */ | ||
| 82 | typedef int SDL_SpinLock; | ||
| 83 | |||
| 84 | /** | ||
| 85 | * Try to lock a spin lock by setting it to a non-zero value. | ||
| 86 | * | ||
| 87 | * ***Please note that spinlocks are dangerous if you don't know what you're | ||
| 88 | * doing. Please be careful using any sort of spinlock!*** | ||
| 89 | * | ||
| 90 | * \param lock a pointer to a lock variable. | ||
| 91 | * \returns true if the lock succeeded, false if the lock is already held. | ||
| 92 | * | ||
| 93 | * \threadsafety It is safe to call this function from any thread. | ||
| 94 | * | ||
| 95 | * \since This function is available since SDL 3.2.0. | ||
| 96 | * | ||
| 97 | * \sa SDL_LockSpinlock | ||
| 98 | * \sa SDL_UnlockSpinlock | ||
| 99 | */ | ||
| 100 | extern SDL_DECLSPEC bool SDLCALL SDL_TryLockSpinlock(SDL_SpinLock *lock); | ||
| 101 | |||
| 102 | /** | ||
| 103 | * Lock a spin lock by setting it to a non-zero value. | ||
| 104 | * | ||
| 105 | * ***Please note that spinlocks are dangerous if you don't know what you're | ||
| 106 | * doing. Please be careful using any sort of spinlock!*** | ||
| 107 | * | ||
| 108 | * \param lock a pointer to a lock variable. | ||
| 109 | * | ||
| 110 | * \threadsafety It is safe to call this function from any thread. | ||
| 111 | * | ||
| 112 | * \since This function is available since SDL 3.2.0. | ||
| 113 | * | ||
| 114 | * \sa SDL_TryLockSpinlock | ||
| 115 | * \sa SDL_UnlockSpinlock | ||
| 116 | */ | ||
| 117 | extern SDL_DECLSPEC void SDLCALL SDL_LockSpinlock(SDL_SpinLock *lock); | ||
| 118 | |||
| 119 | /** | ||
| 120 | * Unlock a spin lock by setting it to 0. | ||
| 121 | * | ||
| 122 | * Always returns immediately. | ||
| 123 | * | ||
| 124 | * ***Please note that spinlocks are dangerous if you don't know what you're | ||
| 125 | * doing. Please be careful using any sort of spinlock!*** | ||
| 126 | * | ||
| 127 | * \param lock a pointer to a lock variable. | ||
| 128 | * | ||
| 129 | * \threadsafety It is safe to call this function from any thread. | ||
| 130 | * | ||
| 131 | * \since This function is available since SDL 3.2.0. | ||
| 132 | * | ||
| 133 | * \sa SDL_LockSpinlock | ||
| 134 | * \sa SDL_TryLockSpinlock | ||
| 135 | */ | ||
| 136 | extern SDL_DECLSPEC void SDLCALL SDL_UnlockSpinlock(SDL_SpinLock *lock); | ||
| 137 | |||
| 138 | |||
| 139 | #ifdef SDL_WIKI_DOCUMENTATION_SECTION | ||
| 140 | |||
| 141 | /** | ||
| 142 | * Mark a compiler barrier. | ||
| 143 | * | ||
| 144 | * A compiler barrier prevents the compiler from reordering reads and writes | ||
| 145 | * to globally visible variables across the call. | ||
| 146 | * | ||
| 147 | * This macro only prevents the compiler from reordering reads and writes, it | ||
| 148 | * does not prevent the CPU from reordering reads and writes. However, all of | ||
| 149 | * the atomic operations that modify memory are full memory barriers. | ||
| 150 | * | ||
| 151 | * \threadsafety Obviously this macro is safe to use from any thread at any | ||
| 152 | * time, but if you find yourself needing this, you are probably | ||
| 153 | * dealing with some very sensitive code; be careful! | ||
| 154 | * | ||
| 155 | * \since This macro is available since SDL 3.2.0. | ||
| 156 | */ | ||
| 157 | #define SDL_CompilerBarrier() DoCompilerSpecificReadWriteBarrier() | ||
| 158 | |||
| 159 | #elif defined(_MSC_VER) && (_MSC_VER > 1200) && !defined(__clang__) | ||
| 160 | void _ReadWriteBarrier(void); | ||
| 161 | #pragma intrinsic(_ReadWriteBarrier) | ||
| 162 | #define SDL_CompilerBarrier() _ReadWriteBarrier() | ||
| 163 | #elif (defined(__GNUC__) && !defined(SDL_PLATFORM_EMSCRIPTEN)) || (defined(__SUNPRO_C) && (__SUNPRO_C >= 0x5120)) | ||
| 164 | /* This is correct for all CPUs when using GCC or Solaris Studio 12.1+. */ | ||
| 165 | #define SDL_CompilerBarrier() __asm__ __volatile__ ("" : : : "memory") | ||
| 166 | #elif defined(__WATCOMC__) | ||
| 167 | extern __inline void SDL_CompilerBarrier(void); | ||
| 168 | #pragma aux SDL_CompilerBarrier = "" parm [] modify exact []; | ||
| 169 | #else | ||
| 170 | #define SDL_CompilerBarrier() \ | ||
| 171 | { SDL_SpinLock _tmp = 0; SDL_LockSpinlock(&_tmp); SDL_UnlockSpinlock(&_tmp); } | ||
| 172 | #endif | ||
| 173 | |||
| 174 | /** | ||
| 175 | * Insert a memory release barrier (function version). | ||
| 176 | * | ||
| 177 | * Please refer to SDL_MemoryBarrierRelease for details. This is a function | ||
| 178 | * version, which might be useful if you need to use this functionality from a | ||
| 179 | * scripting language, etc. Also, some of the macro versions call this | ||
| 180 | * function behind the scenes, where more heavy lifting can happen inside of | ||
| 181 | * SDL. Generally, though, an app written in C/C++/etc should use the macro | ||
| 182 | * version, as it will be more efficient. | ||
| 183 | * | ||
| 184 | * \threadsafety Obviously this function is safe to use from any thread at any | ||
| 185 | * time, but if you find yourself needing this, you are probably | ||
| 186 | * dealing with some very sensitive code; be careful! | ||
| 187 | * | ||
| 188 | * \since This function is available since SDL 3.2.0. | ||
| 189 | * | ||
| 190 | * \sa SDL_MemoryBarrierRelease | ||
| 191 | */ | ||
| 192 | extern SDL_DECLSPEC void SDLCALL SDL_MemoryBarrierReleaseFunction(void); | ||
| 193 | |||
| 194 | /** | ||
| 195 | * Insert a memory acquire barrier (function version). | ||
| 196 | * | ||
| 197 | * Please refer to SDL_MemoryBarrierRelease for details. This is a function | ||
| 198 | * version, which might be useful if you need to use this functionality from a | ||
| 199 | * scripting language, etc. Also, some of the macro versions call this | ||
| 200 | * function behind the scenes, where more heavy lifting can happen inside of | ||
| 201 | * SDL. Generally, though, an app written in C/C++/etc should use the macro | ||
| 202 | * version, as it will be more efficient. | ||
| 203 | * | ||
| 204 | * \threadsafety Obviously this function is safe to use from any thread at any | ||
| 205 | * time, but if you find yourself needing this, you are probably | ||
| 206 | * dealing with some very sensitive code; be careful! | ||
| 207 | * | ||
| 208 | * \since This function is available since SDL 3.2.0. | ||
| 209 | * | ||
| 210 | * \sa SDL_MemoryBarrierAcquire | ||
| 211 | */ | ||
| 212 | extern SDL_DECLSPEC void SDLCALL SDL_MemoryBarrierAcquireFunction(void); | ||
| 213 | |||
| 214 | |||
| 215 | #ifdef SDL_WIKI_DOCUMENTATION_SECTION | ||
| 216 | |||
| 217 | /** | ||
| 218 | * Insert a memory release barrier (macro version). | ||
| 219 | * | ||
| 220 | * Memory barriers are designed to prevent reads and writes from being | ||
| 221 | * reordered by the compiler and being seen out of order on multi-core CPUs. | ||
| 222 | * | ||
| 223 | * A typical pattern would be for thread A to write some data and a flag, and | ||
| 224 | * for thread B to read the flag and get the data. In this case you would | ||
| 225 | * insert a release barrier between writing the data and the flag, | ||
| 226 | * guaranteeing that the data write completes no later than the flag is | ||
| 227 | * written, and you would insert an acquire barrier between reading the flag | ||
| 228 | * and reading the data, to ensure that all the reads associated with the flag | ||
| 229 | * have completed. | ||
| 230 | * | ||
| 231 | * In this pattern you should always see a release barrier paired with an | ||
| 232 | * acquire barrier and you should gate the data reads/writes with a single | ||
| 233 | * flag variable. | ||
| 234 | * | ||
| 235 | * For more information on these semantics, take a look at the blog post: | ||
| 236 | * http://preshing.com/20120913/acquire-and-release-semantics | ||
| 237 | * | ||
| 238 | * This is the macro version of this functionality; if possible, SDL will use | ||
| 239 | * compiler intrinsics or inline assembly, but some platforms might need to | ||
| 240 | * call the function version of this, SDL_MemoryBarrierReleaseFunction to do | ||
| 241 | * the heavy lifting. Apps that can use the macro should favor it over the | ||
| 242 | * function. | ||
| 243 | * | ||
| 244 | * \threadsafety Obviously this macro is safe to use from any thread at any | ||
| 245 | * time, but if you find yourself needing this, you are probably | ||
| 246 | * dealing with some very sensitive code; be careful! | ||
| 247 | * | ||
| 248 | * \since This macro is available since SDL 3.2.0. | ||
| 249 | * | ||
| 250 | * \sa SDL_MemoryBarrierAcquire | ||
| 251 | * \sa SDL_MemoryBarrierReleaseFunction | ||
| 252 | */ | ||
| 253 | #define SDL_MemoryBarrierRelease() SDL_MemoryBarrierReleaseFunction() | ||
| 254 | |||
| 255 | /** | ||
| 256 | * Insert a memory acquire barrier (macro version). | ||
| 257 | * | ||
| 258 | * Please see SDL_MemoryBarrierRelease for the details on what memory barriers | ||
| 259 | * are and when to use them. | ||
| 260 | * | ||
| 261 | * This is the macro version of this functionality; if possible, SDL will use | ||
| 262 | * compiler intrinsics or inline assembly, but some platforms might need to | ||
| 263 | * call the function version of this, SDL_MemoryBarrierAcquireFunction, to do | ||
| 264 | * the heavy lifting. Apps that can use the macro should favor it over the | ||
| 265 | * function. | ||
| 266 | * | ||
| 267 | * \threadsafety Obviously this macro is safe to use from any thread at any | ||
| 268 | * time, but if you find yourself needing this, you are probably | ||
| 269 | * dealing with some very sensitive code; be careful! | ||
| 270 | * | ||
| 271 | * \since This macro is available since SDL 3.2.0. | ||
| 272 | * | ||
| 273 | * \sa SDL_MemoryBarrierRelease | ||
| 274 | * \sa SDL_MemoryBarrierAcquireFunction | ||
| 275 | */ | ||
| 276 | #define SDL_MemoryBarrierAcquire() SDL_MemoryBarrierAcquireFunction() | ||
| 277 | |||
| 278 | #elif defined(__GNUC__) && (defined(__powerpc__) || defined(__ppc__)) | ||
| 279 | #define SDL_MemoryBarrierRelease() __asm__ __volatile__ ("lwsync" : : : "memory") | ||
| 280 | #define SDL_MemoryBarrierAcquire() __asm__ __volatile__ ("lwsync" : : : "memory") | ||
| 281 | #elif defined(__GNUC__) && defined(__aarch64__) | ||
| 282 | #define SDL_MemoryBarrierRelease() __asm__ __volatile__ ("dmb ish" : : : "memory") | ||
| 283 | #define SDL_MemoryBarrierAcquire() __asm__ __volatile__ ("dmb ish" : : : "memory") | ||
| 284 | #elif defined(__GNUC__) && defined(__arm__) | ||
| 285 | #if 0 /* defined(SDL_PLATFORM_LINUX) || defined(SDL_PLATFORM_ANDROID) */ | ||
| 286 | /* Information from: | ||
| 287 | https://chromium.googlesource.com/chromium/chromium/+/trunk/base/atomicops_internals_arm_gcc.h#19 | ||
| 288 | |||
| 289 | The Linux kernel provides a helper function which provides the right code for a memory barrier, | ||
| 290 | hard-coded at address 0xffff0fa0 | ||
| 291 | */ | ||
| 292 | typedef void (*SDL_KernelMemoryBarrierFunc)(); | ||
| 293 | #define SDL_MemoryBarrierRelease() ((SDL_KernelMemoryBarrierFunc)0xffff0fa0)() | ||
| 294 | #define SDL_MemoryBarrierAcquire() ((SDL_KernelMemoryBarrierFunc)0xffff0fa0)() | ||
| 295 | #else | ||
| 296 | #if defined(__ARM_ARCH_7__) || defined(__ARM_ARCH_7A__) || defined(__ARM_ARCH_7EM__) || defined(__ARM_ARCH_7R__) || defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7S__) || defined(__ARM_ARCH_8A__) | ||
| 297 | #define SDL_MemoryBarrierRelease() __asm__ __volatile__ ("dmb ish" : : : "memory") | ||
| 298 | #define SDL_MemoryBarrierAcquire() __asm__ __volatile__ ("dmb ish" : : : "memory") | ||
| 299 | #elif defined(__ARM_ARCH_6__) || defined(__ARM_ARCH_6J__) || defined(__ARM_ARCH_6K__) || defined(__ARM_ARCH_6T2__) || defined(__ARM_ARCH_6Z__) || defined(__ARM_ARCH_6ZK__) | ||
| 300 | #ifdef __thumb__ | ||
| 301 | /* The mcr instruction isn't available in thumb mode, use real functions */ | ||
| 302 | #define SDL_MEMORY_BARRIER_USES_FUNCTION | ||
| 303 | #define SDL_MemoryBarrierRelease() SDL_MemoryBarrierReleaseFunction() | ||
| 304 | #define SDL_MemoryBarrierAcquire() SDL_MemoryBarrierAcquireFunction() | ||
| 305 | #else | ||
| 306 | #define SDL_MemoryBarrierRelease() __asm__ __volatile__ ("mcr p15, 0, %0, c7, c10, 5" : : "r"(0) : "memory") | ||
| 307 | #define SDL_MemoryBarrierAcquire() __asm__ __volatile__ ("mcr p15, 0, %0, c7, c10, 5" : : "r"(0) : "memory") | ||
| 308 | #endif /* __thumb__ */ | ||
| 309 | #else | ||
| 310 | #define SDL_MemoryBarrierRelease() __asm__ __volatile__ ("" : : : "memory") | ||
| 311 | #define SDL_MemoryBarrierAcquire() __asm__ __volatile__ ("" : : : "memory") | ||
| 312 | #endif /* SDL_PLATFORM_LINUX || SDL_PLATFORM_ANDROID */ | ||
| 313 | #endif /* __GNUC__ && __arm__ */ | ||
| 314 | #else | ||
| 315 | #if (defined(__SUNPRO_C) && (__SUNPRO_C >= 0x5120)) | ||
| 316 | /* This is correct for all CPUs on Solaris when using Solaris Studio 12.1+. */ | ||
| 317 | #include <mbarrier.h> | ||
| 318 | #define SDL_MemoryBarrierRelease() __machine_rel_barrier() | ||
| 319 | #define SDL_MemoryBarrierAcquire() __machine_acq_barrier() | ||
| 320 | #else | ||
| 321 | /* This is correct for the x86 and x64 CPUs, and we'll expand this over time. */ | ||
| 322 | #define SDL_MemoryBarrierRelease() SDL_CompilerBarrier() | ||
| 323 | #define SDL_MemoryBarrierAcquire() SDL_CompilerBarrier() | ||
| 324 | #endif | ||
| 325 | #endif | ||
| 326 | |||
| 327 | /* "REP NOP" is PAUSE, coded for tools that don't know it by that name. */ | ||
| 328 | #ifdef SDL_WIKI_DOCUMENTATION_SECTION | ||
| 329 | |||
| 330 | /** | ||
| 331 | * A macro to insert a CPU-specific "pause" instruction into the program. | ||
| 332 | * | ||
| 333 | * This can be useful in busy-wait loops, as it serves as a hint to the CPU as | ||
| 334 | * to the program's intent; some CPUs can use this to do more efficient | ||
| 335 | * processing. On some platforms, this doesn't do anything, so using this | ||
| 336 | * macro might just be a harmless no-op. | ||
| 337 | * | ||
| 338 | * Note that if you are busy-waiting, there are often more-efficient | ||
| 339 | * approaches with other synchronization primitives: mutexes, semaphores, | ||
| 340 | * condition variables, etc. | ||
| 341 | * | ||
| 342 | * \threadsafety This macro is safe to use from any thread. | ||
| 343 | * | ||
| 344 | * \since This macro is available since SDL 3.2.0. | ||
| 345 | */ | ||
| 346 | #define SDL_CPUPauseInstruction() DoACPUPauseInACompilerAndArchitectureSpecificWay | ||
| 347 | |||
| 348 | #elif (defined(__GNUC__) || defined(__clang__)) && (defined(__i386__) || defined(__x86_64__)) | ||
| 349 | #define SDL_CPUPauseInstruction() __asm__ __volatile__("pause\n") /* Some assemblers can't do REP NOP, so go with PAUSE. */ | ||
| 350 | #elif (defined(__arm__) && defined(__ARM_ARCH) && __ARM_ARCH >= 7) || defined(__aarch64__) | ||
| 351 | #define SDL_CPUPauseInstruction() __asm__ __volatile__("yield" ::: "memory") | ||
| 352 | #elif (defined(__powerpc__) || defined(__powerpc64__)) | ||
| 353 | #define SDL_CPUPauseInstruction() __asm__ __volatile__("or 27,27,27"); | ||
| 354 | #elif (defined(__riscv) && __riscv_xlen == 64) | ||
| 355 | #define SDL_CPUPauseInstruction() __asm__ __volatile__(".insn i 0x0F, 0, x0, x0, 0x010"); | ||
| 356 | #elif defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64)) | ||
| 357 | #define SDL_CPUPauseInstruction() _mm_pause() /* this is actually "rep nop" and not a SIMD instruction. No inline asm in MSVC x86-64! */ | ||
| 358 | #elif defined(_MSC_VER) && (defined(_M_ARM) || defined(_M_ARM64)) | ||
| 359 | #define SDL_CPUPauseInstruction() __yield() | ||
| 360 | #elif defined(__WATCOMC__) && defined(__386__) | ||
| 361 | extern __inline void SDL_CPUPauseInstruction(void); | ||
| 362 | #pragma aux SDL_CPUPauseInstruction = ".686p" ".xmm2" "pause" | ||
| 363 | #else | ||
| 364 | #define SDL_CPUPauseInstruction() | ||
| 365 | #endif | ||
| 366 | |||
| 367 | |||
| 368 | /** | ||
| 369 | * A type representing an atomic integer value. | ||
| 370 | * | ||
| 371 | * This can be used to manage a value that is synchronized across multiple | ||
| 372 | * CPUs without a race condition; when an app sets a value with | ||
| 373 | * SDL_SetAtomicInt all other threads, regardless of the CPU it is running on, | ||
| 374 | * will see that value when retrieved with SDL_GetAtomicInt, regardless of CPU | ||
| 375 | * caches, etc. | ||
| 376 | * | ||
| 377 | * This is also useful for atomic compare-and-swap operations: a thread can | ||
| 378 | * change the value as long as its current value matches expectations. When | ||
| 379 | * done in a loop, one can guarantee data consistency across threads without a | ||
| 380 | * lock (but the usual warnings apply: if you don't know what you're doing, or | ||
| 381 | * you don't do it carefully, you can confidently cause any number of | ||
| 382 | * disasters with this, so in most cases, you _should_ use a mutex instead of | ||
| 383 | * this!). | ||
| 384 | * | ||
| 385 | * This is a struct so people don't accidentally use numeric operations on it | ||
| 386 | * directly. You have to use SDL atomic functions. | ||
| 387 | * | ||
| 388 | * \since This struct is available since SDL 3.2.0. | ||
| 389 | * | ||
| 390 | * \sa SDL_CompareAndSwapAtomicInt | ||
| 391 | * \sa SDL_GetAtomicInt | ||
| 392 | * \sa SDL_SetAtomicInt | ||
| 393 | * \sa SDL_AddAtomicInt | ||
| 394 | */ | ||
| 395 | typedef struct SDL_AtomicInt { int value; } SDL_AtomicInt; | ||
| 396 | |||
| 397 | /** | ||
| 398 | * Set an atomic variable to a new value if it is currently an old value. | ||
| 399 | * | ||
| 400 | * ***Note: If you don't know what this function is for, you shouldn't use | ||
| 401 | * it!*** | ||
| 402 | * | ||
| 403 | * \param a a pointer to an SDL_AtomicInt variable to be modified. | ||
| 404 | * \param oldval the old value. | ||
| 405 | * \param newval the new value. | ||
| 406 | * \returns true if the atomic variable was set, false otherwise. | ||
| 407 | * | ||
| 408 | * \threadsafety It is safe to call this function from any thread. | ||
| 409 | * | ||
| 410 | * \since This function is available since SDL 3.2.0. | ||
| 411 | * | ||
| 412 | * \sa SDL_GetAtomicInt | ||
| 413 | * \sa SDL_SetAtomicInt | ||
| 414 | */ | ||
| 415 | extern SDL_DECLSPEC bool SDLCALL SDL_CompareAndSwapAtomicInt(SDL_AtomicInt *a, int oldval, int newval); | ||
| 416 | |||
| 417 | /** | ||
| 418 | * Set an atomic variable to a value. | ||
| 419 | * | ||
| 420 | * This function also acts as a full memory barrier. | ||
| 421 | * | ||
| 422 | * ***Note: If you don't know what this function is for, you shouldn't use | ||
| 423 | * it!*** | ||
| 424 | * | ||
| 425 | * \param a a pointer to an SDL_AtomicInt variable to be modified. | ||
| 426 | * \param v the desired value. | ||
| 427 | * \returns the previous value of the atomic variable. | ||
| 428 | * | ||
| 429 | * \threadsafety It is safe to call this function from any thread. | ||
| 430 | * | ||
| 431 | * \since This function is available since SDL 3.2.0. | ||
| 432 | * | ||
| 433 | * \sa SDL_GetAtomicInt | ||
| 434 | */ | ||
| 435 | extern SDL_DECLSPEC int SDLCALL SDL_SetAtomicInt(SDL_AtomicInt *a, int v); | ||
| 436 | |||
| 437 | /** | ||
| 438 | * Get the value of an atomic variable. | ||
| 439 | * | ||
| 440 | * ***Note: If you don't know what this function is for, you shouldn't use | ||
| 441 | * it!*** | ||
| 442 | * | ||
| 443 | * \param a a pointer to an SDL_AtomicInt variable. | ||
| 444 | * \returns the current value of an atomic variable. | ||
| 445 | * | ||
| 446 | * \threadsafety It is safe to call this function from any thread. | ||
| 447 | * | ||
| 448 | * \since This function is available since SDL 3.2.0. | ||
| 449 | * | ||
| 450 | * \sa SDL_SetAtomicInt | ||
| 451 | */ | ||
| 452 | extern SDL_DECLSPEC int SDLCALL SDL_GetAtomicInt(SDL_AtomicInt *a); | ||
| 453 | |||
| 454 | /** | ||
| 455 | * Add to an atomic variable. | ||
| 456 | * | ||
| 457 | * This function also acts as a full memory barrier. | ||
| 458 | * | ||
| 459 | * ***Note: If you don't know what this function is for, you shouldn't use | ||
| 460 | * it!*** | ||
| 461 | * | ||
| 462 | * \param a a pointer to an SDL_AtomicInt variable to be modified. | ||
| 463 | * \param v the desired value to add. | ||
| 464 | * \returns the previous value of the atomic variable. | ||
| 465 | * | ||
| 466 | * \threadsafety It is safe to call this function from any thread. | ||
| 467 | * | ||
| 468 | * \since This function is available since SDL 3.2.0. | ||
| 469 | * | ||
| 470 | * \sa SDL_AtomicDecRef | ||
| 471 | * \sa SDL_AtomicIncRef | ||
| 472 | */ | ||
| 473 | extern SDL_DECLSPEC int SDLCALL SDL_AddAtomicInt(SDL_AtomicInt *a, int v); | ||
| 474 | |||
| 475 | #ifndef SDL_AtomicIncRef | ||
| 476 | |||
| 477 | /** | ||
| 478 | * Increment an atomic variable used as a reference count. | ||
| 479 | * | ||
| 480 | * ***Note: If you don't know what this macro is for, you shouldn't use it!*** | ||
| 481 | * | ||
| 482 | * \param a a pointer to an SDL_AtomicInt to increment. | ||
| 483 | * \returns the previous value of the atomic variable. | ||
| 484 | * | ||
| 485 | * \threadsafety It is safe to call this macro from any thread. | ||
| 486 | * | ||
| 487 | * \since This macro is available since SDL 3.2.0. | ||
| 488 | * | ||
| 489 | * \sa SDL_AtomicDecRef | ||
| 490 | */ | ||
| 491 | #define SDL_AtomicIncRef(a) SDL_AddAtomicInt(a, 1) | ||
| 492 | #endif | ||
| 493 | |||
| 494 | #ifndef SDL_AtomicDecRef | ||
| 495 | |||
| 496 | /** | ||
| 497 | * Decrement an atomic variable used as a reference count. | ||
| 498 | * | ||
| 499 | * ***Note: If you don't know what this macro is for, you shouldn't use it!*** | ||
| 500 | * | ||
| 501 | * \param a a pointer to an SDL_AtomicInt to decrement. | ||
| 502 | * \returns true if the variable reached zero after decrementing, false | ||
| 503 | * otherwise. | ||
| 504 | * | ||
| 505 | * \threadsafety It is safe to call this macro from any thread. | ||
| 506 | * | ||
| 507 | * \since This macro is available since SDL 3.2.0. | ||
| 508 | * | ||
| 509 | * \sa SDL_AtomicIncRef | ||
| 510 | */ | ||
| 511 | #define SDL_AtomicDecRef(a) (SDL_AddAtomicInt(a, -1) == 1) | ||
| 512 | #endif | ||
| 513 | |||
| 514 | /** | ||
| 515 | * A type representing an atomic unsigned 32-bit value. | ||
| 516 | * | ||
| 517 | * This can be used to manage a value that is synchronized across multiple | ||
| 518 | * CPUs without a race condition; when an app sets a value with | ||
| 519 | * SDL_SetAtomicU32 all other threads, regardless of the CPU it is running on, | ||
| 520 | * will see that value when retrieved with SDL_GetAtomicU32, regardless of CPU | ||
| 521 | * caches, etc. | ||
| 522 | * | ||
| 523 | * This is also useful for atomic compare-and-swap operations: a thread can | ||
| 524 | * change the value as long as its current value matches expectations. When | ||
| 525 | * done in a loop, one can guarantee data consistency across threads without a | ||
| 526 | * lock (but the usual warnings apply: if you don't know what you're doing, or | ||
| 527 | * you don't do it carefully, you can confidently cause any number of | ||
| 528 | * disasters with this, so in most cases, you _should_ use a mutex instead of | ||
| 529 | * this!). | ||
| 530 | * | ||
| 531 | * This is a struct so people don't accidentally use numeric operations on it | ||
| 532 | * directly. You have to use SDL atomic functions. | ||
| 533 | * | ||
| 534 | * \since This struct is available since SDL 3.2.0. | ||
| 535 | * | ||
| 536 | * \sa SDL_CompareAndSwapAtomicU32 | ||
| 537 | * \sa SDL_GetAtomicU32 | ||
| 538 | * \sa SDL_SetAtomicU32 | ||
| 539 | */ | ||
| 540 | typedef struct SDL_AtomicU32 { Uint32 value; } SDL_AtomicU32; | ||
| 541 | |||
| 542 | /** | ||
| 543 | * Set an atomic variable to a new value if it is currently an old value. | ||
| 544 | * | ||
| 545 | * ***Note: If you don't know what this function is for, you shouldn't use | ||
| 546 | * it!*** | ||
| 547 | * | ||
| 548 | * \param a a pointer to an SDL_AtomicU32 variable to be modified. | ||
| 549 | * \param oldval the old value. | ||
| 550 | * \param newval the new value. | ||
| 551 | * \returns true if the atomic variable was set, false otherwise. | ||
| 552 | * | ||
| 553 | * \threadsafety It is safe to call this function from any thread. | ||
| 554 | * | ||
| 555 | * \since This function is available since SDL 3.2.0. | ||
| 556 | * | ||
| 557 | * \sa SDL_GetAtomicU32 | ||
| 558 | * \sa SDL_SetAtomicU32 | ||
| 559 | */ | ||
| 560 | extern SDL_DECLSPEC bool SDLCALL SDL_CompareAndSwapAtomicU32(SDL_AtomicU32 *a, Uint32 oldval, Uint32 newval); | ||
| 561 | |||
| 562 | /** | ||
| 563 | * Set an atomic variable to a value. | ||
| 564 | * | ||
| 565 | * This function also acts as a full memory barrier. | ||
| 566 | * | ||
| 567 | * ***Note: If you don't know what this function is for, you shouldn't use | ||
| 568 | * it!*** | ||
| 569 | * | ||
| 570 | * \param a a pointer to an SDL_AtomicU32 variable to be modified. | ||
| 571 | * \param v the desired value. | ||
| 572 | * \returns the previous value of the atomic variable. | ||
| 573 | * | ||
| 574 | * \threadsafety It is safe to call this function from any thread. | ||
| 575 | * | ||
| 576 | * \since This function is available since SDL 3.2.0. | ||
| 577 | * | ||
| 578 | * \sa SDL_GetAtomicU32 | ||
| 579 | */ | ||
| 580 | extern SDL_DECLSPEC Uint32 SDLCALL SDL_SetAtomicU32(SDL_AtomicU32 *a, Uint32 v); | ||
| 581 | |||
| 582 | /** | ||
| 583 | * Get the value of an atomic variable. | ||
| 584 | * | ||
| 585 | * ***Note: If you don't know what this function is for, you shouldn't use | ||
| 586 | * it!*** | ||
| 587 | * | ||
| 588 | * \param a a pointer to an SDL_AtomicU32 variable. | ||
| 589 | * \returns the current value of an atomic variable. | ||
| 590 | * | ||
| 591 | * \threadsafety It is safe to call this function from any thread. | ||
| 592 | * | ||
| 593 | * \since This function is available since SDL 3.2.0. | ||
| 594 | * | ||
| 595 | * \sa SDL_SetAtomicU32 | ||
| 596 | */ | ||
| 597 | extern SDL_DECLSPEC Uint32 SDLCALL SDL_GetAtomicU32(SDL_AtomicU32 *a); | ||
| 598 | |||
| 599 | /** | ||
| 600 | * Set a pointer to a new value if it is currently an old value. | ||
| 601 | * | ||
| 602 | * ***Note: If you don't know what this function is for, you shouldn't use | ||
| 603 | * it!*** | ||
| 604 | * | ||
| 605 | * \param a a pointer to a pointer. | ||
| 606 | * \param oldval the old pointer value. | ||
| 607 | * \param newval the new pointer value. | ||
| 608 | * \returns true if the pointer was set, false otherwise. | ||
| 609 | * | ||
| 610 | * \threadsafety It is safe to call this function from any thread. | ||
| 611 | * | ||
| 612 | * \since This function is available since SDL 3.2.0. | ||
| 613 | * | ||
| 614 | * \sa SDL_CompareAndSwapAtomicInt | ||
| 615 | * \sa SDL_GetAtomicPointer | ||
| 616 | * \sa SDL_SetAtomicPointer | ||
| 617 | */ | ||
| 618 | extern SDL_DECLSPEC bool SDLCALL SDL_CompareAndSwapAtomicPointer(void **a, void *oldval, void *newval); | ||
| 619 | |||
| 620 | /** | ||
| 621 | * Set a pointer to a value atomically. | ||
| 622 | * | ||
| 623 | * ***Note: If you don't know what this function is for, you shouldn't use | ||
| 624 | * it!*** | ||
| 625 | * | ||
| 626 | * \param a a pointer to a pointer. | ||
| 627 | * \param v the desired pointer value. | ||
| 628 | * \returns the previous value of the pointer. | ||
| 629 | * | ||
| 630 | * \threadsafety It is safe to call this function from any thread. | ||
| 631 | * | ||
| 632 | * \since This function is available since SDL 3.2.0. | ||
| 633 | * | ||
| 634 | * \sa SDL_CompareAndSwapAtomicPointer | ||
| 635 | * \sa SDL_GetAtomicPointer | ||
| 636 | */ | ||
| 637 | extern SDL_DECLSPEC void * SDLCALL SDL_SetAtomicPointer(void **a, void *v); | ||
| 638 | |||
| 639 | /** | ||
| 640 | * Get the value of a pointer atomically. | ||
| 641 | * | ||
| 642 | * ***Note: If you don't know what this function is for, you shouldn't use | ||
| 643 | * it!*** | ||
| 644 | * | ||
| 645 | * \param a a pointer to a pointer. | ||
| 646 | * \returns the current value of a pointer. | ||
| 647 | * | ||
| 648 | * \threadsafety It is safe to call this function from any thread. | ||
| 649 | * | ||
| 650 | * \since This function is available since SDL 3.2.0. | ||
| 651 | * | ||
| 652 | * \sa SDL_CompareAndSwapAtomicPointer | ||
| 653 | * \sa SDL_SetAtomicPointer | ||
| 654 | */ | ||
| 655 | extern SDL_DECLSPEC void * SDLCALL SDL_GetAtomicPointer(void **a); | ||
| 656 | |||
| 657 | /* Ends C function definitions when using C++ */ | ||
| 658 | #ifdef __cplusplus | ||
| 659 | } | ||
| 660 | #endif | ||
| 661 | |||
| 662 | #include <SDL3/SDL_close_code.h> | ||
| 663 | |||
| 664 | #endif /* SDL_atomic_h_ */ | ||
