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      1 /*
      2     SDL - Simple DirectMedia Layer
      3     Copyright (C) 1997-2006 Sam Lantinga
      4 
      5     This library is free software; you can redistribute it and/or
      6     modify it under the terms of the GNU Lesser General Public
      7     License as published by the Free Software Foundation; either
      8     version 2.1 of the License, or (at your option) any later version.
      9 
     10     This library is distributed in the hope that it will be useful,
     11     but WITHOUT ANY WARRANTY; without even the implied warranty of
     12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     13     Lesser General Public License for more details.
     14 
     15     You should have received a copy of the GNU Lesser General Public
     16     License along with this library; if not, write to the Free Software
     17     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
     18 
     19     Sam Lantinga
     20     slouken (at) libsdl.org
     21 */
     22 #include "SDL_config.h"
     23 
     24 /* An implementation of semaphores using mutexes and condition variables */
     25 
     26 #include "SDL_thread.h"
     27 #include "SDL_systhread_c.h"
     28 
     29 
     30 struct SDL_semaphore
     31 {
     32 	struct SignalSemaphore Sem;
     33 };
     34 
     35 #undef D
     36 
     37 #define D(x)
     38 
     39 SDL_sem *SDL_CreateSemaphore(Uint32 initial_value)
     40 {
     41 	SDL_sem *sem;
     42 
     43 	sem = (SDL_sem *)SDL_malloc(sizeof(*sem));
     44 
     45 	if ( ! sem ) {
     46 		SDL_OutOfMemory();
     47 		return(0);
     48 	}
     49 
     50 	D(bug("Creating semaphore %lx...\n",sem));
     51 
     52 	SDL_memset(sem,0,sizeof(*sem));
     53 
     54 	InitSemaphore(&sem->Sem);
     55 
     56 	return(sem);
     57 }
     58 
     59 void SDL_DestroySemaphore(SDL_sem *sem)
     60 {
     61 	D(bug("Destroying semaphore %lx...\n",sem));
     62 
     63 	if ( sem ) {
     64 // Condizioni per liberare i task in attesa?
     65 		SDL_free(sem);
     66 	}
     67 }
     68 
     69 int SDL_SemTryWait(SDL_sem *sem)
     70 {
     71 	if ( ! sem ) {
     72 		SDL_SetError("Passed a NULL semaphore");
     73 		return -1;
     74 	}
     75 
     76 	D(bug("TryWait semaphore...%lx\n",sem));
     77 
     78 	ObtainSemaphore(&sem->Sem);
     79 //	ReleaseSemaphore(&sem->Sem);
     80 
     81 	return 1;
     82 }
     83 
     84 int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
     85 {
     86 	int retval;
     87 
     88 
     89 	if ( ! sem ) {
     90 		SDL_SetError("Passed a NULL semaphore");
     91 		return -1;
     92 	}
     93 
     94 	D(bug("WaitTimeout (%ld) semaphore...%lx\n",timeout,sem));
     95 
     96 	/* A timeout of 0 is an easy case */
     97 	if ( timeout == 0 ) {
     98 		ObtainSemaphore(&sem->Sem);
     99 		return 1;
    100 	}
    101 	if(!(retval=AttemptSemaphore(&sem->Sem)))
    102 	{
    103 		SDL_Delay(timeout);
    104 		retval=AttemptSemaphore(&sem->Sem);
    105 	}
    106 
    107 	if(retval==TRUE)
    108 	{
    109 //		ReleaseSemaphore(&sem->Sem);
    110 		retval=1;
    111 	}
    112 
    113 	return retval;
    114 }
    115 
    116 int SDL_SemWait(SDL_sem *sem)
    117 {
    118 	ObtainSemaphore(&sem->Sem);
    119 	return 0;
    120 }
    121 
    122 Uint32 SDL_SemValue(SDL_sem *sem)
    123 {
    124 	Uint32 value;
    125 
    126 	value = 0;
    127 	if ( sem ) {
    128 		#ifdef STORMC4_WOS
    129 		value = sem->Sem.ssppc_SS.ss_NestCount;
    130 		#else
    131 		value = sem->Sem.ss_NestCount;
    132 		#endif
    133 	}
    134 	return value;
    135 }
    136 
    137 int SDL_SemPost(SDL_sem *sem)
    138 {
    139 	if ( ! sem ) {
    140 		SDL_SetError("Passed a NULL semaphore");
    141 		return -1;
    142 	}
    143 	D(bug("SemPost semaphore...%lx\n",sem));
    144 
    145 	ReleaseSemaphore(&sem->Sem);
    146 	return 0;
    147 }
    148 
    149