initial

scheduler.c

@@ -0,0 +1,105 @@
+#include <stdlib.h>
+#include <msp430g2553.h>
+#include "scheduler.h"
+
+tTask tasks[MAX_NUM_OF_TASKS];
+
+
+uint32_t seconds;
+
+void schInit() {
+  TACCR0 = 19600;
+  TACCTL0 = CCIE;
+  TACTL = MC_1 | ID_0 | TASSEL_2 | TACLR;
+
+  for (uint16_t i = 0; i < MAX_NUM_OF_TASKS; i++) {
+    tasks[i].delay = 0;
+    tasks[i].period = 0;
+    tasks[i].run = 0;
+    tasks[i].exec = NULL;
+    tasks[i].handle = NULL;
+  }
+
+  seconds = 0;
+
+  // LED
+  P1DIR |= BIT0;
+  P1OUT &= ~BIT0;
+}
+
+void __attribute__ ((interrupt (TIMER0_A0_VECTOR))) schUpdate() {
+  static uint16_t milliSeconds = 0;
+  if (milliSeconds >= 1000) {
+    seconds += 1;
+    milliSeconds = 0;
+    P1OUT ^= BIT0;
+  }
+  milliSeconds += 1;
+
+  for (uint16_t i = 0; i < MAX_NUM_OF_TASKS; i++) {
+    if (tasks[i].exec != NULL) {
+      if (tasks[i].delay == 0) {
+        tasks[i].delay = tasks[i].period;
+        tasks[i].run++;
+      } else {
+        tasks[i].delay--;
+      }
+    }
+  }
+}
+
+uint16_t schAdd(void (*exec)(void *), void *handle, uint32_t delay, uint32_t period) {
+  uint16_t taskId = 0xffff;
+  for (uint16_t i = 0; i < MAX_NUM_OF_TASKS; i++) {
+    if (tasks[i].exec == NULL) {
+      tasks[i].delay = delay;
+      tasks[i].period = period;
+      if (delay == 0 && period == 0) {
+        tasks[i].run = 1;
+      } else {
+        tasks[i].run = 0;
+      }
+      tasks[i].exec = exec;
+      tasks[i].handle = handle;
+      taskId = i;
+      break;
+    }
+  }
+  return taskId;
+}
+
+void schDel(uint16_t taskId) {
+  tasks[taskId].exec = NULL;
+}
+
+void schExec() {
+  for (uint16_t i = 0; i < MAX_NUM_OF_TASKS; i++) {
+    // synchronize access to tasks[].run
+    __disable_interrupt(); 
+    if (tasks[i].exec != NULL && tasks[i].run > 0) {
+      tasks[i].run--;
+      // synchronize access to tasks[].run
+      // reenable interrupts before actually executing task
+      __enable_interrupt();
+      tasks[i].exec(tasks[i].handle);
+      if (tasks[i].period == 0) {
+        tasks[i].exec = NULL;
+      }
+    } else {
+      // synchronize access to tasks[].run
+      // reenable interrupts in case task is not yet executable
+      __enable_interrupt();
+    }
+  }
+}
+
+uint32_t getSeconds() {
+  uint32_t s;
+
+  __disable_interrupt();
+  s = seconds;
+  __enable_interrupt();
+
+  return s;
+}
+