Various improvements to example task systems in examples/.

- Only have a single copy of all of the tasks_*.cpp sample implementations,
  stored in examples/.
- Reduce dynamic storage allocation and locking in task launch code paths.
- Don't have a hard limit of the number of tasks that can be launched on
  Windows (fix issue #85).

examples/tasks_concrt.cpp

@@ -0,0 +1,104 @@
+/*
+  Copyright (c) 2011, Intel Corporation
+  All rights reserved.
+
+  Redistribution and use in source and binary forms, with or without
+  modification, are permitted provided that the following conditions are
+  met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above copyright
+      notice, this list of conditions and the following disclaimer in the
+      documentation and/or other materials provided with the distribution.
+
+    * Neither the name of Intel Corporation nor the names of its
+      contributors may be used to endorse or promote products derived from
+      this software without specific prior written permission.
+
+
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+   IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+   TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+   PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+   OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.  
+*/
+
+#include "taskinfo.h"
+
+/* Simple task system implementation for ispc based on Microsoft's
+   Concurrency Runtime. */
+
+#include <windows.h>
+#include <concrt.h>
+using namespace Concurrency;
+#include <stdint.h>
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <algorithm>
+
+// ispc expects these functions to have C linkage / not be mangled
+extern "C" { 
+    void ISPCLaunch(void *f, void *data);
+    void ISPCSync();
+    void *ISPCMalloc(int64_t size, int32_t alignment);
+    void ISPCFree(void *ptr);
+}
+
+
+void __cdecl
+lRunTask(LPVOID param) {
+    TaskInfo *ti = (TaskInfo *)param;
+    
+    // Actually run the task. 
+    // FIXME: like the GCD implementation for OS X, this is passing bogus
+    // values for the threadIndex and threadCount builtins, which in turn
+    // will cause bugs in code that uses those.
+    int threadIndex = 0;
+    int threadCount = 1;
+    TaskFuncType func = (TaskFuncType)ti->func;
+    func(ti->data, threadIndex, threadCount);
+
+    // Signal the event that this task is done
+    ti->taskEvent.set();
+}
+
+
+void
+ISPCLaunch(void *func, void *data) {
+    TaskInfo *ti = lGetTaskInfo();
+    ti->func = (TaskFuncType)func;
+    ti->data = data;
+	ti->taskEvent.reset();
+    CurrentScheduler::ScheduleTask(lRunTask, ti);
+}
+
+
+void ISPCSync() {
+    for (int i = 0; i < nextTaskInfoCoordinate; ++i) {
+		int index = (i >> LOG_TASK_QUEUE_CHUNK_SIZE);
+		int offset = i & (TASK_QUEUE_CHUNK_SIZE-1);
+		taskInfo[index][offset].taskEvent.wait();
+		taskInfo[index][offset].taskEvent.reset();
+    }
+
+    lResetTaskInfo();
+}
+
+
+void *ISPCMalloc(int64_t size, int32_t alignment) {
+    return _aligned_malloc(size, alignment);
+}
+
+
+void ISPCFree(void *ptr) {
+    _aligned_free(ptr);
+}