--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/thread/nds/SDL_syscond.c	Wed Aug 27 15:10:03 2008 +0000
@@ -0,0 +1,229 @@
+/*
+    SDL - Simple DirectMedia Layer
+    Copyright (C) 1997, 1998, 1999, 2000, 2001  Sam Lantinga
+
+    This library is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Library General Public
+    License as published by the Free Software Foundation; either
+    version 2 of the License, or (at your option) any later version.
+
+    This library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    Library General Public License for more details.
+
+    You should have received a copy of the GNU Library General Public
+    License along with this library; if not, write to the Free
+    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+
+    Sam Lantinga
+    slouken@devolution.com
+*/
+
+#ifdef SAVE_RCSID
+static char rcsid =
+    "@(#) $Id: SDL_syscond.c,v 1.2 2001/04/26 16:50:18 hercules Exp $";
+#endif
+
+/* An implementation of condition variables using semaphores and mutexes */
+/*
+   This implementation borrows heavily from the BeOS condition variable
+   implementation, written by Christopher Tate and Owen Smith.  Thanks!
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "SDL_error.h"
+#include "SDL_thread.h"
+
+struct SDL_cond
+{
+    SDL_mutex *lock;
+    int waiting;
+    int signals;
+    SDL_sem *wait_sem;
+    SDL_sem *wait_done;
+};
+
+/* Create a condition variable */
+SDL_cond *
+SDL_CreateCond(void)
+{
+    SDL_cond *cond;
+
+    cond = (SDL_cond *) malloc(sizeof(SDL_cond));
+    if (cond) {
+        cond->lock = SDL_CreateMutex();
+        cond->wait_sem = SDL_CreateSemaphore(0);
+        cond->wait_done = SDL_CreateSemaphore(0);
+        cond->waiting = cond->signals = 0;
+        if (!cond->lock || !cond->wait_sem || !cond->wait_done) {
+            SDL_DestroyCond(cond);
+            cond = NULL;
+        }
+    } else {
+        SDL_OutOfMemory();
+    }
+    return (cond);
+}
+
+/* Destroy a condition variable */
+void
+SDL_DestroyCond(SDL_cond * cond)
+{
+    if (cond) {
+        if (cond->wait_sem) {
+            SDL_DestroySemaphore(cond->wait_sem);
+        }
+        if (cond->wait_done) {
+            SDL_DestroySemaphore(cond->wait_done);
+        }
+        if (cond->lock) {
+            SDL_DestroyMutex(cond->lock);
+        }
+        free(cond);
+    }
+}
+
+/* Restart one of the threads that are waiting on the condition variable */
+int
+SDL_CondSignal(SDL_cond * cond)
+{
+    if (!cond) {
+        SDL_SetError("Passed a NULL condition variable");
+        return -1;
+    }
+
+    /* If there are waiting threads not already signalled, then
+       signal the condition and wait for the thread to respond.
+     */
+    SDL_LockMutex(cond->lock);
+    if (cond->waiting > cond->signals) {
+        ++cond->signals;
+        SDL_SemPost(cond->wait_sem);
+        SDL_UnlockMutex(cond->lock);
+        SDL_SemWait(cond->wait_done);
+    } else {
+        SDL_UnlockMutex(cond->lock);
+    }
+
+    return 0;
+}
+
+/* Restart all threads that are waiting on the condition variable */
+int
+SDL_CondBroadcast(SDL_cond * cond)
+{
+    if (!cond) {
+        SDL_SetError("Passed a NULL condition variable");
+        return -1;
+    }
+
+    /* If there are waiting threads not already signalled, then
+       signal the condition and wait for the thread to respond.
+     */
+    SDL_LockMutex(cond->lock);
+    if (cond->waiting > cond->signals) {
+        int i, num_waiting;
+
+        num_waiting = (cond->waiting - cond->signals);
+        cond->signals = cond->waiting;
+        for (i = 0; i < num_waiting; ++i) {
+            SDL_SemPost(cond->wait_sem);
+        }
+        /* Now all released threads are blocked here, waiting for us.
+           Collect them all (and win fabulous prizes!) :-)
+         */
+        SDL_UnlockMutex(cond->lock);
+        for (i = 0; i < num_waiting; ++i) {
+            SDL_SemWait(cond->wait_done);
+        }
+    } else {
+        SDL_UnlockMutex(cond->lock);
+    }
+
+    return 0;
+}
+
+/* Wait on the condition variable for at most 'ms' milliseconds.
+   The mutex must be locked before entering this function!
+   The mutex is unlocked during the wait, and locked again after the wait.
+
+Typical use:
+
+Thread A:
+	SDL_LockMutex(lock);
+	while ( ! condition ) {
+		SDL_CondWait(cond);
+	}
+	SDL_UnlockMutex(lock);
+
+Thread B:
+	SDL_LockMutex(lock);
+	...
+	condition = true;
+	...
+	SDL_UnlockMutex(lock);
+ */
+int
+SDL_CondWaitTimeout(SDL_cond * cond, SDL_mutex * mutex, Uint32 ms)
+{
+    int retval;
+
+    if (!cond) {
+        SDL_SetError("Passed a NULL condition variable");
+        return -1;
+    }
+
+    /* Obtain the protection mutex, and increment the number of waiters.
+       This allows the signal mechanism to only perform a signal if there
+       are waiting threads.
+     */
+    SDL_LockMutex(cond->lock);
+    ++cond->waiting;
+    SDL_UnlockMutex(cond->lock);
+
+    /* Unlock the mutex, as is required by condition variable semantics */
+    SDL_UnlockMutex(mutex);
+
+    /* Wait for a signal */
+    if (ms == SDL_MUTEX_MAXWAIT) {
+        retval = SDL_SemWait(cond->wait_sem);
+    } else {
+        retval = SDL_SemWaitTimeout(cond->wait_sem, ms);
+    }
+
+    /* Let the signaler know we have completed the wait, otherwise
+       the signaler can race ahead and get the condition semaphore
+       if we are stopped between the mutex unlock and semaphore wait,
+       giving a deadlock.  See the following URL for details:
+       http://www-classic.be.com/aboutbe/benewsletter/volume_III/Issue40.html
+     */
+    SDL_LockMutex(cond->lock);
+    if (cond->signals > 0) {
+        /* If we timed out, we need to eat a condition signal */
+        if (retval > 0) {
+            SDL_SemWait(cond->wait_sem);
+        }
+        /* We always notify the signal thread that we are done */
+        SDL_SemPost(cond->wait_done);
+
+        /* Signal handshake complete */
+        --cond->signals;
+    }
+    --cond->waiting;
+    SDL_UnlockMutex(cond->lock);
+
+    /* Lock the mutex, as is required by condition variable semantics */
+    SDL_LockMutex(mutex);
+
+    return retval;
+}
+
+/* Wait on the condition variable forever */
+int
+SDL_CondWait(SDL_cond * cond, SDL_mutex * mutex)
+{
+    return SDL_CondWaitTimeout(cond, mutex, SDL_MUTEX_MAXWAIT);
+}