Diff: capi/us_ticker_api.c

Revision:

4:c4bfb462ca53

Child:

6:6dfdb79ccc45

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/capi/us_ticker_api.c	Wed Mar 13 15:04:05 2013 +0000
@@ -0,0 +1,113 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2013 ARM Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include <stddef.h>
+#include "us_ticker_api.h"
+
+static ticker_event_handler event_handler;
+static ticker_event_t *head = NULL;
+
+void us_ticker_set_handler(ticker_event_handler handler) {
+    us_ticker_init();
+    
+    event_handler = handler;
+}
+
+void us_ticker_irq_handler(void) {
+    us_ticker_clear_interrupt();
+    
+    /* Go through all the pending TimerEvents */
+    while (1) {
+        if (head == NULL) {
+            // There are no more TimerEvents left, so disable matches.
+            us_ticker_disable_interrupt();
+            return;
+        }
+        
+        if ((int)(head->timestamp - us_ticker_read()) <= 0) {
+            // This event was in the past:
+            //      point to the following one and execute its handler
+            ticker_event_t *p = head;
+            head = head->next;
+            if (event_handler != NULL) {
+                event_handler(p->id); // NOTE: the handler can set new events
+            }
+        } else {
+            // This event and the following ones in the list are in the future:
+            //      set it as next interrupt and return
+            us_ticker_set_interrupt(head->timestamp);
+            return;
+        }
+    }
+}
+
+void us_ticker_insert_event(ticker_event_t *obj, unsigned int timestamp, uint32_t id) {
+    /* disable interrupts for the duration of the function */
+    __disable_irq();
+    
+    // initialise our data
+    obj->timestamp = timestamp;
+    obj->id = id;
+    
+    /* Go through the list until we either reach the end, or find
+       an element this should come before (which is possibly the
+       head). */
+    ticker_event_t *prev = NULL, *p = head;
+    while (p != NULL) {
+        /* check if we come before p */
+        if ((int)(timestamp - p->timestamp) <= 0) {
+            break;
+        }
+        /* go to the next element */
+        prev = p;
+        p = p->next;
+    }
+    /* if prev is NULL we're at the head */
+    if (prev == NULL) {
+        head = obj;
+        us_ticker_set_interrupt(timestamp);
+    } else {
+        prev->next = obj;
+    }
+    /* if we're at the end p will be NULL, which is correct */
+    obj->next = p;
+    
+    __enable_irq();
+}
+
+void us_ticker_remove_event(ticker_event_t *obj) {
+    __disable_irq();
+    
+    // remove this object from the list
+    if (head == obj) {
+        // first in the list, so just drop me
+        head = obj->next;
+        if (obj->next != NULL) {
+            us_ticker_set_interrupt(head->timestamp);
+        }
+    } else {
+        // find the object before me, then drop me
+        ticker_event_t* p = head;
+        while (p != NULL) {
+            if (p->next == obj) {
+                p->next = obj->next;
+                break;
+            }
+            p = p->next;
+        }
+    }
+    
+    __enable_irq();
+}