初始版本

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

@@ -0,0 +1,97 @@
+/**
+ * This is a very small example that shows how to use
+ * protothreads. The program consists of two protothreads that wait
+ * for each other to toggle a variable.
+ */
+
+/* We must always include pt.h in our protothreads code. */
+#include "pt.h"
+
+#include <stdio.h> /* For printf(). */
+
+/* Two flags that the two protothread functions use. */
+static int protothread1_flag, protothread2_flag;
+
+/**
+ * The first protothread function. A protothread function must always
+ * return an integer, but must never explicitly return - returning is
+ * performed inside the protothread statements.
+ *
+ * The protothread function is driven by the main loop further down in
+ * the code.
+ */
+static int
+protothread1(struct pt *pt)
+{
+  /* A protothread function must begin with PT_BEGIN() which takes a
+     pointer to a struct pt. */
+  PT_BEGIN(pt);
+
+  /* We loop forever here. */
+  while(1) {
+    /* Wait until the other protothread has set its flag. */
+    PT_WAIT_UNTIL(pt, protothread2_flag != 0);
+    printf("Protothread 1 running\n");
+
+    /* We then reset the other protothread's flag, and set our own
+       flag so that the other protothread can run. */
+    protothread2_flag = 0;
+    protothread1_flag = 1;
+
+    /* And we loop. */
+  }
+
+  /* All protothread functions must end with PT_END() which takes a
+     pointer to a struct pt. */
+  PT_END(pt);
+}
+
+/**
+ * The second protothread function. This is almost the same as the
+ * first one.
+ */
+static int
+protothread2(struct pt *pt)
+{
+  PT_BEGIN(pt);
+
+  while(1) {
+    /* Let the other protothread run. */
+    protothread2_flag = 1;
+
+    /* Wait until the other protothread has set its flag. */
+    PT_WAIT_UNTIL(pt, protothread1_flag != 0);
+    printf("Protothread 2 running\n");
+    
+    /* We then reset the other protothread's flag. */
+    protothread1_flag = 0;
+
+    /* And we loop. */
+  }
+  PT_END(pt);
+}
+
+/**
+ * Finally, we have the main loop. Here is where the protothreads are
+ * initialized and scheduled. First, however, we define the
+ * protothread state variables pt1 and pt2, which hold the state of
+ * the two protothreads.
+ */
+static struct pt pt1, pt2;
+int
+main(void)
+{
+  /* Initialize the protothread state variables with PT_INIT(). */
+  PT_INIT(&pt1);
+  PT_INIT(&pt2);
+  
+  /*
+   * Then we schedule the two protothreads by repeatedly calling their
+   * protothread functions and passing a pointer to the protothread
+   * state variables as arguments.
+   */
+  while(1) {
+    protothread1(&pt1);
+    protothread2(&pt2);
+  }
+}