project additions/changes

labW9barnestr/Src/tasker.c

@@ -0,0 +1,76 @@
+/**
+ * @file tasker.c
+ * @author Trevor Barnes
+ * @brief 
+ * @version 0.1
+ * @date 2022-02-11
+ * 
+ * @copyright Copyright (c) 2022
+ * 
+ */
+
+#include <stdio.h>
+#include <inttypes.h>
+#include "tasker.h"
+
+void SysTick_Init() {
+
+}
+
+void init_task(uint32_t task_num, uint32_t stacksize, void(*entry_point)(void), uint32_t ticks) {
+    tasks[task_num].stack_pointer = (uint32_t*)malloc(stacksize*sizeof(uint32_t));
+    tasks[task_num].stack_pointer += stacksize;
+    *(--tasks[task_num].stack_pointer) = 0x01000000; // PSR
+    *(--tasks[task_num].stack_pointer) = ((uint32_t)entry_point);
+    *(--tasks[task_num].stack_pointer) = 0xFFFFFFFF;
+    *(--tasks[task_num].stack_pointer) = 0; // R12
+    *(--tasks[task_num].stack_pointer) = 0; // R3
+    *(--tasks[task_num].stack_pointer) = 0; // R2
+    *(--tasks[task_num].stack_pointer) = 0; // R1
+    *(--tasks[task_num].stack_pointer) = 0; // R0
+    *(--tasks[task_num].stack_pointer) = 0xFFFFFFF9; // ISR LR
+    *(--tasks[task_num].stack_pointer) = 0; // R11
+    *(--tasks[task_num].stack_pointer) = 0; // R10
+    *(--tasks[task_num].stack_pointer) = 0; // R9
+    *(--tasks[task_num].stack_pointer) = 0; // R8
+    *(--tasks[task_num].stack_pointer) = 0; // R7
+    *(--tasks[task_num].stack_pointer) = 0; // R6
+    *(--tasks[task_num].stack_pointer) = 0; // R5
+    *(--tasks[task_num].stack_pointer) = 0; // R4
+    tasks[task_num].state = ACTIVE;
+    tasks[task_num].ticks_starting = ticks;
+    tasks[task_num].ticks_remaining = 0;
+}
+
+void init_tasker(uint32_t total_tasks, uint32_t main_ticks) {
+    num_tasks = total_tasks;
+    *tasks = calloc(total_tasks, sizeof(Task));
+}
+
+
+void tasker_tick() {
+    tasks[current_task].ticks_remaining--;
+
+    if(tasks[current_task].ticks_remaining == 0) {
+        int i = 1;
+        while(tasks[(next_task = (current_task + i)%num_tasks)].state != ACTIVE) {
+            i++;
+        }
+        tasks[next_task].ticks_remaining = tasks[next_task].ticks_starting;
+        //*scb_icsr |= 1<<PENDSVSET;
+    }
+}
+
+void SysTick_Handler(void) {
+    
+}
+
+void PendSV_Handler(void) {
+    register uint32_t* stack_pointer asm("r13");
+    asm volatile("push {r4-r11,lr}");
+    tasks[current_task].stack_pointer = stack_pointer;
+    current_task = next_task;
+    stack_pointer = tasks[current_task].stack_pointer;
+    asm volatile("pop {r4-r11,lr}\n\t"
+                 "bx lr");
+}