src/atomic/SDL_spinlock.c
author Sam Lantinga
Mon, 09 Jan 2017 11:58:01 -0800
changeset 10802 6afc9b833867
parent 10737 3406a0f8b041
child 11318 06fd8421e8f6
permissions -rw-r--r--
We only need the first few keymaps corresponding to the following constants:
K_NORMTAB, K_SHIFTTAB, K_ALTTAB, K_ALTSHIFTTAB

In the normal case we'll load all the keymaps from the kernel, but this reduces the size of the SDL library for the fallback case when we can't get to the tty.
     1 /*
     2   Simple DirectMedia Layer
     3   Copyright (C) 1997-2017 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 #if defined(__WIN32__) || defined(__WINRT__)
    24 #include "../core/windows/SDL_windows.h"
    25 #endif
    26 
    27 #include "SDL_atomic.h"
    28 #include "SDL_mutex.h"
    29 #include "SDL_timer.h"
    30 
    31 #if !defined(HAVE_GCC_ATOMICS) && defined(__SOLARIS__)
    32 #include <atomic.h>
    33 #endif
    34 
    35 /* This function is where all the magic happens... */
    36 SDL_bool
    37 SDL_AtomicTryLock(SDL_SpinLock *lock)
    38 {
    39 #if SDL_ATOMIC_DISABLED
    40     /* Terrible terrible damage */
    41     static SDL_mutex *_spinlock_mutex;
    42 
    43     if (!_spinlock_mutex) {
    44         /* Race condition on first lock... */
    45         _spinlock_mutex = SDL_CreateMutex();
    46     }
    47     SDL_LockMutex(_spinlock_mutex);
    48     if (*lock == 0) {
    49         *lock = 1;
    50         SDL_UnlockMutex(_spinlock_mutex);
    51         return SDL_TRUE;
    52     } else {
    53         SDL_UnlockMutex(_spinlock_mutex);
    54         return SDL_FALSE;
    55     }
    56 
    57 #elif defined(_MSC_VER)
    58     SDL_COMPILE_TIME_ASSERT(locksize, sizeof(*lock) == sizeof(long));
    59     return (InterlockedExchange((long*)lock, 1) == 0);
    60 
    61 #elif HAVE_GCC_ATOMICS || HAVE_GCC_SYNC_LOCK_TEST_AND_SET
    62     return (__sync_lock_test_and_set(lock, 1) == 0);
    63 
    64 #elif defined(__GNUC__) && defined(__arm__) && \
    65         (defined(__ARM_ARCH_4__) || defined(__ARM_ARCH_4T__) || \
    66          defined(__ARM_ARCH_5__) || defined(__ARM_ARCH_5TE__) || \
    67          defined(__ARM_ARCH_5TEJ__))
    68     int result;
    69     __asm__ __volatile__ (
    70         "swp %0, %1, [%2]\n"
    71         : "=&r,&r" (result) : "r,0" (1), "r,r" (lock) : "memory");
    72     return (result == 0);
    73 
    74 #elif defined(__GNUC__) && defined(__arm__)
    75     int result;
    76     __asm__ __volatile__ (
    77         "ldrex %0, [%2]\nteq   %0, #0\nstrexeq %0, %1, [%2]"
    78         : "=&r" (result) : "r" (1), "r" (lock) : "cc", "memory");
    79     return (result == 0);
    80 
    81 #elif defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
    82     int result;
    83     __asm__ __volatile__(
    84         "lock ; xchgl %0, (%1)\n"
    85         : "=r" (result) : "r" (lock), "0" (1) : "cc", "memory");
    86     return (result == 0);
    87 
    88 #elif defined(__MACOSX__) || defined(__IPHONEOS__)
    89     /* Maybe used for PowerPC, but the Intel asm or gcc atomics are favored. */
    90     return OSAtomicCompareAndSwap32Barrier(0, 1, lock);
    91 
    92 #elif defined(__SOLARIS__) && defined(_LP64)
    93     /* Used for Solaris with non-gcc compilers. */
    94     return (SDL_bool) ((int) atomic_cas_64((volatile uint64_t*)lock, 0, 1) == 0);
    95 
    96 #elif defined(__SOLARIS__) && !defined(_LP64)
    97     /* Used for Solaris with non-gcc compilers. */
    98     return (SDL_bool) ((int) atomic_cas_32((volatile uint32_t*)lock, 0, 1) == 0);
    99 
   100 #else
   101 #error Please implement for your platform.
   102     return SDL_FALSE;
   103 #endif
   104 }
   105 
   106 void
   107 SDL_AtomicLock(SDL_SpinLock *lock)
   108 {
   109     /* FIXME: Should we have an eventual timeout? */
   110     while (!SDL_AtomicTryLock(lock)) {
   111         SDL_Delay(0);
   112     }
   113 }
   114 
   115 void
   116 SDL_AtomicUnlock(SDL_SpinLock *lock)
   117 {
   118 #if defined(_MSC_VER)
   119     _ReadWriteBarrier();
   120     *lock = 0;
   121 
   122 #elif HAVE_GCC_ATOMICS || HAVE_GCC_SYNC_LOCK_TEST_AND_SET
   123     __sync_lock_release(lock);
   124 
   125 #elif defined(__SOLARIS__)
   126     /* Used for Solaris when not using gcc. */
   127     *lock = 0;
   128     membar_producer();
   129 
   130 #else
   131     *lock = 0;
   132 #endif
   133 }
   134 
   135 /* vi: set ts=4 sw=4 expandtab: */