Refactor time functions to own source

Author: aedrax

README.md

@@ -30,8 +30,9 @@ Function|Description
 
 I ported the examples found in the protothreads distribution to async.h. Here
 is the async.h equivalent of the protothreads sample on the home page:
-```C
+```c
 #include "async.h"
+#include "async-time.h"
 
 struct async pt;
 struct timer timer;
@@ -41,7 +42,7 @@ async example(struct async *pt) {
 
     while(1) {
         if(initiate_io()) {
-            timer_start(&timer);
+            timer_set(&timer);
             await(io_completed() || timer_expired(&timer));
             read_data();
         }
@@ -55,12 +56,13 @@ to accept the async structure/local continuation as an argument.
 
 Here is the same example as above, but where the timer is lifted to
 a local parameter:
-```C
+```c
 #include "async.h"
+#include "async-time.h"
 
 typedef struct { 
     async_state;    // declare the asynchronous state
-    timer timer;    // declare local state
+    struct timer timer;    // declare local state
 } example_state;
 example_state pt;
 
@@ -69,7 +71,7 @@ async example(example_state *pt) {
     
     while(1) {
         if(initiate_io()) {
-            timer_start(&pt->timer);
+            timer_set(&pt->timer);
             await(io_completed() || timer_expired(&pt->timer));
             read_data();
         }

async/Makefile

@@ -2,7 +2,7 @@ CC = gcc
 CCFlags = -Wall
 BUILD_DIR = build
 
-SRC = example-buffer.c example-codelock.c example-small.c main.c
+SRC = async-time.c example-buffer.c example-codelock.c example-small.c main.c
 OBJ = $(patsubst %.c,$(BUILD_DIR)/%.o,$(SRC))
 
 all : $(OBJ)

async/async-time.c

@@ -0,0 +1,49 @@
+#ifdef _WIN32
+#include <windows.h>
+#else
+#include <unistd.h>
+#include <sys/time.h>
+#endif
+
+#include "async.h"
+#include "async-time.h"
+
+#ifdef _WIN32
+
+static int clock_time(void)
+{
+    return (int)GetTickCount();
+}
+
+#else /* _WIN32 */
+
+static int clock_time(void)
+{
+    struct timeval tv;
+    struct timezone tz;
+    gettimeofday(&tv, &tz);
+    return tv.tv_sec * 1000 + tv.tv_usec / 1000;
+}
+
+#endif /* _WIN32 */
+
+int timer_expired(struct timer *t)
+{
+    return (int)(clock_time() - t->start) >= (int)t->interval;
+}
+
+void timer_set(struct timer *t, unsigned int interval)
+{
+    t->interval = interval;
+    t->start = clock_time();
+}
+
+async async_sleep(struct async_sleep_state *state, unsigned int usecs)
+{
+    async_begin(state);
+
+    timer_set(&state->timer, usecs);
+    await(timer_expired(&state->timer));
+
+    async_end;
+}

async/async-time.h

@@ -0,0 +1,42 @@
+#include "async.h"
+
+/**
+ * Timer structure for tracking when a timer has expired
+ */
+struct timer
+{
+    unsigned int start;
+    unsigned int interval;
+};
+
+/**
+ * State structure for calls to the async_sleep function
+ */
+struct async_sleep_state
+{
+    async_state;
+    struct timer timer;
+};
+
+/**
+ * Initialize a timer with a specified time duration
+ *
+ * @param t timer struct to initialize
+ * @param usecs number of milliseconds the timer is good for
+ */
+void timer_set(struct timer *t, unsigned int usecs);
+
+/**
+ * Determine if the supplied timer is expired
+ * 
+ * @param t timer struct to examine for expiration
+ */
+int timer_expired(struct timer *t);
+
+/**
+ * Sleep asynchronously for a specified duration
+ * 
+ * @param state async_sleep_state structure to hold state of operation
+ * @param usecs number of milliseconds to sleep for
+ */
+async async_sleep(struct async_sleep_state *state, unsigned int usecs);

async/example-codelock.c

@@ -61,16 +61,8 @@
 #include <stdio.h>
 
 #include "async.h"
+#include "async-time.h"
 
-/*---------------------------------------------------------------------------*/
-/*
- * The following definitions are just for the simple timer library
- * used in this example. The actual implementation of the functions
- * can be found at the end of this file.
- */
-struct timer { int start, interval; };
-static int  timer_expired(struct timer *t);
-static void timer_set(struct timer *t, int usecs);
 /*---------------------------------------------------------------------------*/
 /*
  * This example uses two timers: one for the code lock async and
@@ -374,30 +366,4 @@ example_codelock(void)
 
   return 0;
 }
-/*---------------------------------------------------------------------------*/
-/*
- * Finally, the implementation of the simple timer library follows.
- */
-#ifdef _WIN32
-
-static int clock_time(void)
-{ return (int)GetTickCount(); }
 
-#else /* _WIN32 */
-
-static int clock_time(void)
-{
-  struct timeval tv;
-  struct timezone tz;   
-  gettimeofday(&tv, &tz); 
-  return tv.tv_sec * 1000 + tv.tv_usec / 1000;
-}
-
-#endif /* _WIN32 */
-
-static int timer_expired(struct timer *t)
-{ return (int)(clock_time() - t->start) >= (int)t->interval; }
-
-static void timer_set(struct timer *t, int interval)
-{ t->interval = interval; t->start = clock_time(); }
-/*---------------------------------------------------------------------------*/