src/atomic/SDL_atomic.c
author Ozkan Sezer <sezeroz@gmail.com>
Thu, 27 Sep 2018 11:55:02 +0300
changeset 12241 f72836cfb92b
parent 11811 5d94cb6b24d3
child 12503 806492103856
permissions -rw-r--r--
SDL_atomic.c, SDL_spinlock.c: use lock prefix with xchg in Watcom asm.
     1 /*
     2   Simple DirectMedia Layer
     3   Copyright (C) 1997-2018 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 #include "../SDL_internal.h"
    22 
    23 #include "SDL_atomic.h"
    24 
    25 #if defined(_MSC_VER) && (_MSC_VER >= 1500)
    26 #include <intrin.h>
    27 #define HAVE_MSC_ATOMICS 1
    28 #endif
    29 
    30 #if defined(__MACOSX__)  /* !!! FIXME: should we favor gcc atomics? */
    31 #include <libkern/OSAtomic.h>
    32 #endif
    33 
    34 #if !defined(HAVE_GCC_ATOMICS) && defined(__SOLARIS__)
    35 #include <atomic.h>
    36 #endif
    37 
    38 /* The __atomic_load_n() intrinsic showed up in different times for different compilers. */
    39 #if defined(HAVE_GCC_ATOMICS)
    40 # if defined(__clang__)
    41 #   if __has_builtin(__atomic_load_n)
    42       /* !!! FIXME: this advertises as available in the NDK but uses an external symbol we don't have.
    43          It might be in a later NDK or we might need an extra library? --ryan. */
    44 #     if !defined(__ANDROID__)
    45 #       define HAVE_ATOMIC_LOAD_N 1
    46 #     endif
    47 #   endif
    48 # elif defined(__GNUC__)
    49 #   if (__GNUC__ >= 5)
    50 #     define HAVE_ATOMIC_LOAD_N 1
    51 #   endif
    52 # endif
    53 #endif
    54 
    55 #if defined(__WATCOMC__) && defined(__386__)
    56 SDL_COMPILE_TIME_ASSERT(intsize, 4==sizeof(int));
    57 #define HAVE_WATCOM_ATOMICS
    58 extern _inline int _SDL_xchg_watcom(volatile int *a, int v);
    59 #pragma aux _SDL_xchg_watcom = \
    60   "lock xchg [ecx], eax" \
    61   parm [ecx] [eax] \
    62   value [eax] \
    63   modify exact [eax];
    64 
    65 extern _inline unsigned char _SDL_cmpxchg_watcom(volatile int *a, int newval, int oldval);
    66 #pragma aux _SDL_cmpxchg_watcom = \
    67   "lock cmpxchg [edx], ecx" \
    68   "setz al" \
    69   parm [edx] [ecx] [eax] \
    70   value [al] \
    71   modify exact [eax];
    72 
    73 extern _inline int _SDL_xadd_watcom(volatile int *a, int v);
    74 #pragma aux _SDL_xadd_watcom = \
    75   "lock xadd [ecx], eax" \
    76   parm [ecx] [eax] \
    77   value [eax] \
    78   modify exact [eax];
    79 #endif /* __WATCOMC__ && __386__ */
    80 
    81 /*
    82   If any of the operations are not provided then we must emulate some
    83   of them. That means we need a nice implementation of spin locks
    84   that avoids the "one big lock" problem. We use a vector of spin
    85   locks and pick which one to use based on the address of the operand
    86   of the function.
    87 
    88   To generate the index of the lock we first shift by 3 bits to get
    89   rid on the zero bits that result from 32 and 64 bit allignment of
    90   data. We then mask off all but 5 bits and use those 5 bits as an
    91   index into the table.
    92 
    93   Picking the lock this way insures that accesses to the same data at
    94   the same time will go to the same lock. OTOH, accesses to different
    95   data have only a 1/32 chance of hitting the same lock. That should
    96   pretty much eliminate the chances of several atomic operations on
    97   different data from waiting on the same "big lock". If it isn't
    98   then the table of locks can be expanded to a new size so long as
    99   the new size is a power of two.
   100 
   101   Contributed by Bob Pendleton, bob@pendleton.com
   102 */
   103 
   104 #if !defined(HAVE_MSC_ATOMICS) && !defined(HAVE_GCC_ATOMICS) && !defined(__MACOSX__) && !defined(__SOLARIS__) && !defined(HAVE_WATCOM_ATOMICS)
   105 #define EMULATE_CAS 1
   106 #endif
   107 
   108 #if EMULATE_CAS
   109 static SDL_SpinLock locks[32];
   110 
   111 static SDL_INLINE void
   112 enterLock(void *a)
   113 {
   114     uintptr_t index = ((((uintptr_t)a) >> 3) & 0x1f);
   115 
   116     SDL_AtomicLock(&locks[index]);
   117 }
   118 
   119 static SDL_INLINE void
   120 leaveLock(void *a)
   121 {
   122     uintptr_t index = ((((uintptr_t)a) >> 3) & 0x1f);
   123 
   124     SDL_AtomicUnlock(&locks[index]);
   125 }
   126 #endif
   127 
   128 
   129 SDL_bool
   130 SDL_AtomicCAS(SDL_atomic_t *a, int oldval, int newval)
   131 {
   132 #ifdef HAVE_MSC_ATOMICS
   133     return (_InterlockedCompareExchange((long*)&a->value, (long)newval, (long)oldval) == (long)oldval);
   134 #elif defined(HAVE_WATCOM_ATOMICS)
   135     return (SDL_bool) _SDL_cmpxchg_watcom(&a->value, newval, oldval);
   136 #elif defined(HAVE_GCC_ATOMICS)
   137     return (SDL_bool) __sync_bool_compare_and_swap(&a->value, oldval, newval);
   138 #elif defined(__MACOSX__)  /* this is deprecated in 10.12 sdk; favor gcc atomics. */
   139     return (SDL_bool) OSAtomicCompareAndSwap32Barrier(oldval, newval, &a->value);
   140 #elif defined(__SOLARIS__) && defined(_LP64)
   141     return (SDL_bool) ((int) atomic_cas_64((volatile uint64_t*)&a->value, (uint64_t)oldval, (uint64_t)newval) == oldval);
   142 #elif defined(__SOLARIS__) && !defined(_LP64)
   143     return (SDL_bool) ((int) atomic_cas_32((volatile uint32_t*)&a->value, (uint32_t)oldval, (uint32_t)newval) == oldval);
   144 #elif EMULATE_CAS
   145     SDL_bool retval = SDL_FALSE;
   146 
   147     enterLock(a);
   148     if (a->value == oldval) {
   149         a->value = newval;
   150         retval = SDL_TRUE;
   151     }
   152     leaveLock(a);
   153 
   154     return retval;
   155 #else
   156     #error Please define your platform.
   157 #endif
   158 }
   159 
   160 SDL_bool
   161 SDL_AtomicCASPtr(void **a, void *oldval, void *newval)
   162 {
   163 #if defined(HAVE_MSC_ATOMICS) && (_M_IX86)
   164     return (_InterlockedCompareExchange((long*)a, (long)newval, (long)oldval) == (long)oldval);
   165 #elif defined(HAVE_MSC_ATOMICS) && (!_M_IX86)
   166     return (_InterlockedCompareExchangePointer(a, newval, oldval) == oldval);
   167 #elif defined(HAVE_WATCOM_ATOMICS)
   168     return (SDL_bool) _SDL_cmpxchg_watcom((int *)a, (long)newval, (long)oldval);
   169 #elif defined(HAVE_GCC_ATOMICS)
   170     return __sync_bool_compare_and_swap(a, oldval, newval);
   171 #elif defined(__MACOSX__) && defined(__LP64__)  /* this is deprecated in 10.12 sdk; favor gcc atomics. */
   172     return (SDL_bool) OSAtomicCompareAndSwap64Barrier((int64_t)oldval, (int64_t)newval, (int64_t*) a);
   173 #elif defined(__MACOSX__) && !defined(__LP64__)  /* this is deprecated in 10.12 sdk; favor gcc atomics. */
   174     return (SDL_bool) OSAtomicCompareAndSwap32Barrier((int32_t)oldval, (int32_t)newval, (int32_t*) a);
   175 #elif defined(__SOLARIS__)
   176     return (SDL_bool) (atomic_cas_ptr(a, oldval, newval) == oldval);
   177 #elif EMULATE_CAS
   178     SDL_bool retval = SDL_FALSE;
   179 
   180     enterLock(a);
   181     if (*a == oldval) {
   182         *a = newval;
   183         retval = SDL_TRUE;
   184     }
   185     leaveLock(a);
   186 
   187     return retval;
   188 #else
   189     #error Please define your platform.
   190 #endif
   191 }
   192 
   193 int
   194 SDL_AtomicSet(SDL_atomic_t *a, int v)
   195 {
   196 #ifdef HAVE_MSC_ATOMICS
   197     return _InterlockedExchange((long*)&a->value, v);
   198 #elif defined(HAVE_WATCOM_ATOMICS)
   199     return _SDL_xchg_watcom(&a->value, v);
   200 #elif defined(HAVE_GCC_ATOMICS)
   201     return __sync_lock_test_and_set(&a->value, v);
   202 #elif defined(__SOLARIS__) && defined(_LP64)
   203     return (int) atomic_swap_64((volatile uint64_t*)&a->value, (uint64_t)v);
   204 #elif defined(__SOLARIS__) && !defined(_LP64)
   205     return (int) atomic_swap_32((volatile uint32_t*)&a->value, (uint32_t)v);
   206 #else
   207     int value;
   208     do {
   209         value = a->value;
   210     } while (!SDL_AtomicCAS(a, value, v));
   211     return value;
   212 #endif
   213 }
   214 
   215 void*
   216 SDL_AtomicSetPtr(void **a, void *v)
   217 {
   218 #if defined(HAVE_MSC_ATOMICS) && (_M_IX86)
   219     return (void *) _InterlockedExchange((long *)a, (long) v);
   220 #elif defined(HAVE_MSC_ATOMICS) && (!_M_IX86)
   221     return _InterlockedExchangePointer(a, v);
   222 #elif defined(HAVE_WATCOM_ATOMICS)
   223     return (void *) _SDL_xchg_watcom((int *)a, (long)v);
   224 #elif defined(HAVE_GCC_ATOMICS)
   225     return __sync_lock_test_and_set(a, v);
   226 #elif defined(__SOLARIS__)
   227     return atomic_swap_ptr(a, v);
   228 #else
   229     void *value;
   230     do {
   231         value = *a;
   232     } while (!SDL_AtomicCASPtr(a, value, v));
   233     return value;
   234 #endif
   235 }
   236 
   237 int
   238 SDL_AtomicAdd(SDL_atomic_t *a, int v)
   239 {
   240 #ifdef HAVE_MSC_ATOMICS
   241     return _InterlockedExchangeAdd((long*)&a->value, v);
   242 #elif defined(HAVE_WATCOM_ATOMICS)
   243     return _SDL_xadd_watcom(&a->value, v);
   244 #elif defined(HAVE_GCC_ATOMICS)
   245     return __sync_fetch_and_add(&a->value, v);
   246 #elif defined(__SOLARIS__)
   247     int pv = a->value;
   248     membar_consumer();
   249 #if defined(_LP64)
   250     atomic_add_64((volatile uint64_t*)&a->value, v);
   251 #elif !defined(_LP64)
   252     atomic_add_32((volatile uint32_t*)&a->value, v);
   253 #endif
   254     return pv;
   255 #else
   256     int value;
   257     do {
   258         value = a->value;
   259     } while (!SDL_AtomicCAS(a, value, (value + v)));
   260     return value;
   261 #endif
   262 }
   263 
   264 int
   265 SDL_AtomicGet(SDL_atomic_t *a)
   266 {
   267 #ifdef HAVE_ATOMIC_LOAD_N
   268     return __atomic_load_n(&a->value, __ATOMIC_SEQ_CST);
   269 #else
   270     int value;
   271     do {
   272         value = a->value;
   273     } while (!SDL_AtomicCAS(a, value, value));
   274     return value;
   275 #endif
   276 }
   277 
   278 void *
   279 SDL_AtomicGetPtr(void **a)
   280 {
   281 #ifdef HAVE_ATOMIC_LOAD_N
   282     return __atomic_load_n(a, __ATOMIC_SEQ_CST);
   283 #else
   284     void *value;
   285     do {
   286         value = *a;
   287     } while (!SDL_AtomicCASPtr(a, value, value));
   288     return value;
   289 #endif
   290 }
   291 
   292 void
   293 SDL_MemoryBarrierReleaseFunction(void)
   294 {
   295     SDL_MemoryBarrierRelease();
   296 }
   297 
   298 void
   299 SDL_MemoryBarrierAcquireFunction(void)
   300 {
   301     SDL_MemoryBarrierAcquire();
   302 }
   303 
   304 /* vi: set ts=4 sw=4 expandtab: */