初始版本

external/protothreads/pt-1.4/example-buffer.c

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+/*
+ * Copyright (c) 2004-2005, Swedish Institute of Computer Science.
+ * All rights reserved. 
+ *
+ * Redistribution and use in source and binary forms, with or without 
+ * modification, are permitted provided that the following conditions 
+ * are met: 
+ * 1. Redistributions of source code must retain the above copyright 
+ *    notice, this list of conditions and the following disclaimer. 
+ * 2. 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. 
+ * 3. Neither the name of the Institute 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 INSTITUTE 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 INSTITUTE 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. 
+ *
+ * This file is part of the protothreads library.
+ *
+ * Author: Adam Dunkels <adam@sics.se>
+ *
+ * $Id: example-buffer.c,v 1.5 2005/10/07 05:21:33 adam Exp $
+ */
+
+#ifdef _WIN32
+#include <windows.h>
+#else
+#include <unistd.h>
+#endif
+#include <stdio.h>
+
+#include "pt-sem.h"
+ 
+#define NUM_ITEMS 32
+#define BUFSIZE 8
+
+static int buffer[BUFSIZE];
+static int bufptr;
+
+static void
+add_to_buffer(int item)
+{
+  printf("Item %d added to buffer at place %d\n", item, bufptr);  
+  buffer[bufptr] = item;
+  bufptr = (bufptr + 1) % BUFSIZE;
+}
+static int
+get_from_buffer(void)
+{
+  int item;
+  item = buffer[bufptr];
+  printf("Item %d retrieved from buffer at place %d\n",
+	 item, bufptr);
+  bufptr = (bufptr + 1) % BUFSIZE;
+  return item;
+}
+
+static int
+produce_item(void)
+{
+  static int item = 0;
+  printf("Item %d produced\n", item);
+  return item++;
+}
+
+static void
+consume_item(int item)
+{
+  printf("Item %d consumed\n", item);
+}
+
+static struct pt_sem full, empty;
+ 
+static 
+PT_THREAD(producer(struct pt *pt))
+{
+  static int produced;
+  
+  PT_BEGIN(pt);
+  
+  for(produced = 0; produced < NUM_ITEMS; ++produced) {
+  
+    PT_SEM_WAIT(pt, &full);
+    
+    add_to_buffer(produce_item());
+    
+    PT_SEM_SIGNAL(pt, &empty);
+  }
+
+  PT_END(pt);
+}
+ 
+static 
+PT_THREAD(consumer(struct pt *pt))
+{
+  static int consumed;
+  
+  PT_BEGIN(pt);
+ 
+  for(consumed = 0; consumed < NUM_ITEMS; ++consumed) {
+    
+    PT_SEM_WAIT(pt, &empty);
+    
+    consume_item(get_from_buffer());    
+    
+    PT_SEM_SIGNAL(pt, &full);
+  }
+ 
+  PT_END(pt);
+}
+ 
+static 
+PT_THREAD(driver_thread(struct pt *pt))
+{
+  static struct pt pt_producer, pt_consumer;
+ 
+  PT_BEGIN(pt);
+  
+  PT_SEM_INIT(&empty, 0);
+  PT_SEM_INIT(&full, BUFSIZE);
+ 
+  PT_INIT(&pt_producer);
+  PT_INIT(&pt_consumer);
+ 
+  PT_WAIT_THREAD(pt, producer(&pt_producer) &
+		     consumer(&pt_consumer));
+ 
+  PT_END(pt);
+}
+
+
+int
+main(void)
+{
+  struct pt driver_pt;
+
+  PT_INIT(&driver_pt);
+
+  while(PT_SCHEDULE(driver_thread(&driver_pt))) {
+
+    /*
+     * When running this example on a multitasking system, we must
+     * give other processes a chance to run too and therefore we call
+     * usleep() resp. Sleep() here. On a dedicated embedded system,
+     * we usually do not need to do this.
+     */
+#ifdef _WIN32
+    Sleep(0);
+#else
+    usleep(10);
+#endif
+  }
+  return 0;
+}