diff options
Diffstat (limited to 'Source/3rdParty/SDL2/src/atomic/SDL_spinlock.c')
| -rw-r--r-- | Source/3rdParty/SDL2/src/atomic/SDL_spinlock.c | 28 |
1 files changed, 26 insertions, 2 deletions
diff --git a/Source/3rdParty/SDL2/src/atomic/SDL_spinlock.c b/Source/3rdParty/SDL2/src/atomic/SDL_spinlock.c index 1ebc718..6a7b14a 100644 --- a/Source/3rdParty/SDL2/src/atomic/SDL_spinlock.c +++ b/Source/3rdParty/SDL2/src/atomic/SDL_spinlock.c @@ -32,11 +32,15 @@ #include <atomic.h> #endif +#if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64)) +#include <xmmintrin.h> +#endif + #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 = \ - "xchg [ecx], eax" \ + "lock xchg [ecx], eax" \ parm [ecx] [eax] \ value [eax] \ modify exact [eax]; @@ -116,12 +120,32 @@ SDL_AtomicTryLock(SDL_SpinLock *lock) #endif } +/* "REP NOP" is PAUSE, coded for tools that don't know it by that name. */ +#if (defined(__GNUC__) || defined(__clang__)) && (defined(__i386__) || defined(__x86_64__)) + #define PAUSE_INSTRUCTION() __asm__ __volatile__("pause\n") /* Some assemblers can't do REP NOP, so go with PAUSE. */ +#elif defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64)) + #define PAUSE_INSTRUCTION() _mm_pause() /* this is actually "rep nop" and not a SIMD instruction. No inline asm in MSVC x86-64! */ +#elif defined(__WATCOMC__) && defined(__386__) + /* watcom assembler rejects PAUSE if CPU < i686, and it refuses REP NOP as an invalid combination. Hardcode the bytes. */ + extern _inline void PAUSE_INSTRUCTION(void); + #pragma aux PAUSE_INSTRUCTION = "db 0f3h,90h" +#else + #define PAUSE_INSTRUCTION() +#endif + void SDL_AtomicLock(SDL_SpinLock *lock) { + int iterations = 0; /* FIXME: Should we have an eventual timeout? */ while (!SDL_AtomicTryLock(lock)) { - SDL_Delay(0); + if (iterations < 32) { + iterations++; + PAUSE_INSTRUCTION(); + } else { + /* !!! FIXME: this doesn't definitely give up the current timeslice, it does different things on various platforms. */ + SDL_Delay(0); + } } } |