19682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall/* 29682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall SDL - Simple DirectMedia Layer 39682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall Copyright (C) 1997-2012 Sam Lantinga 49682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall 59682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall This library is free software; you can redistribute it and/or 69682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall modify it under the terms of the GNU Lesser General Public 79682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall License as published by the Free Software Foundation; either 89682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall version 2.1 of the License, or (at your option) any later version. 99682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall 109682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall This library is distributed in the hope that it will be useful, 119682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall but WITHOUT ANY WARRANTY; without even the implied warranty of 129682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 139682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall Lesser General Public License for more details. 149682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall 159682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall You should have received a copy of the GNU Lesser General Public 169682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall License along with this library; if not, write to the Free Software 179682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA 189682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall 199682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall Sam Lantinga 209682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall slouken@libsdl.org 219682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall*/ 229682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall#include "SDL_config.h" 239682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall 249682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall/* An implementation of mutexes using semaphores */ 259682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall 269682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall#include "SDL_thread.h" 279682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall#include "SDL_systhread_c.h" 289682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall 299682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall 309682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hallstruct SDL_mutex { 319682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall int recursive; 329682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall Uint32 owner; 339682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall SDL_sem *sem; 349682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall}; 359682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall 369682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall/* Create a mutex */ 379682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse HallSDL_mutex *SDL_CreateMutex(void) 389682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall{ 399682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall SDL_mutex *mutex; 409682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall 419682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall /* Allocate mutex memory */ 429682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall mutex = (SDL_mutex *)SDL_malloc(sizeof(*mutex)); 439682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall if ( mutex ) { 449682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall /* Create the mutex semaphore, with initial value 1 */ 459682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall mutex->sem = SDL_CreateSemaphore(1); 469682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall mutex->recursive = 0; 479682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall mutex->owner = 0; 489682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall if ( ! mutex->sem ) { 499682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall SDL_free(mutex); 509682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall mutex = NULL; 519682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall } 529682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall } else { 539682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall SDL_OutOfMemory(); 549682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall } 559682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall return mutex; 569682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall} 579682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall 589682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall/* Free the mutex */ 599682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hallvoid SDL_DestroyMutex(SDL_mutex *mutex) 609682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall{ 619682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall if ( mutex ) { 629682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall if ( mutex->sem ) { 639682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall SDL_DestroySemaphore(mutex->sem); 649682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall } 659682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall SDL_free(mutex); 669682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall } 679682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall} 689682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall 699682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall/* Lock the semaphore */ 709682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hallint SDL_mutexP(SDL_mutex *mutex) 719682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall{ 729682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall#if SDL_THREADS_DISABLED 739682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall return 0; 749682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall#else 759682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall Uint32 this_thread; 769682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall 779682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall if ( mutex == NULL ) { 789682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall SDL_SetError("Passed a NULL mutex"); 799682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall return -1; 809682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall } 819682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall 829682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall this_thread = SDL_ThreadID(); 839682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall if ( mutex->owner == this_thread ) { 849682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall ++mutex->recursive; 859682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall } else { 869682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall /* The order of operations is important. 879682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall We set the locking thread id after we obtain the lock 889682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall so unlocks from other threads will fail. 899682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall */ 909682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall SDL_SemWait(mutex->sem); 919682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall mutex->owner = this_thread; 929682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall mutex->recursive = 0; 939682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall } 949682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall 959682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall return 0; 969682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall#endif /* SDL_THREADS_DISABLED */ 979682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall} 989682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall 999682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall/* Unlock the mutex */ 1009682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hallint SDL_mutexV(SDL_mutex *mutex) 1019682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall{ 1029682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall#if SDL_THREADS_DISABLED 1039682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall return 0; 1049682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall#else 1059682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall if ( mutex == NULL ) { 1069682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall SDL_SetError("Passed a NULL mutex"); 1079682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall return -1; 1089682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall } 1099682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall 1109682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall /* If we don't own the mutex, we can't unlock it */ 1119682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall if ( SDL_ThreadID() != mutex->owner ) { 1129682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall SDL_SetError("mutex not owned by this thread"); 1139682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall return -1; 1149682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall } 1159682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall 1169682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall if ( mutex->recursive ) { 1179682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall --mutex->recursive; 1189682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall } else { 1199682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall /* The order of operations is important. 1209682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall First reset the owner so another thread doesn't lock 1219682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall the mutex and set the ownership before we reset it, 1229682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall then release the lock semaphore. 1239682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall */ 1249682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall mutex->owner = 0; 1259682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall SDL_SemPost(mutex->sem); 1269682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall } 1279682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall return 0; 1289682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall#endif /* SDL_THREADS_DISABLED */ 1299682c8870b8ff5e4ac2e4c70b759f791c6f38c1fJesse Hall} 130