feat: added support for waiting on an irq

kernel/tasks/task.c

@@ -13,15 +13,24 @@
 
 #define stack_end(task) ((task)->stack + ((task)->stack_page_count * PAGE_SIZE))
 
+#define TASK_STATE_UNKNOWN      (0)
+#define TASK_STATE_RUNNABLE     (1 << 0)
+#define TASK_STATE_RUNNING      (1 << 1)
+#define TASK_STATE_WAIT_IRQ     (1 << 2)
+
+#define TASK_STATE_ERROR        (1 << 7)
+
+
 typedef struct task {
     bool present: 1;
-    uint8_t wait_irq: 4;
+    uint8_t state;
+    uint16_t wait_irq;
 
     uint32_t tid;
 
     struct task *next;
 
-    void* stack;
+    void *stack;
     uint32_t stack_page_count;
 
     task_registers_t *task_registers;
@@ -37,15 +46,20 @@ typedef struct {
 
 bool task_locked = false;
 
+task_t *idle_task = NULL;
 task_t *first_task = NULL;
 task_t *last_task = NULL;
 task_t *current_task = NULL;
 
 uint32_t last_tid = 0;
 
-extern switch_task(task_registers_t**, task_registers_t*);
+extern switch_task(task_registers_t
+**, task_registers_t*);
+
 extern cdecl noreturn void __task_entry_point();
+
 extern noreturn void __task_entry_point_inner();
+
 // explicit cdecl calling convention
 void cdecl noreturn task_entry_point(task_entrypoint entrypoint, void *entry_data) {
     entrypoint(entry_data);
@@ -61,6 +75,28 @@ void task_lock_free() {
     task_locked = false;
 }
 
+void noreturn task_idle(void *data) {
+    while (true) __asm__("hlt");
+}
+
+void task_notify_irq(uint8_t irq_no) {
+    uint16_t irq__bit = 1 << irq_no;
+    task_t *t = first_task;
+    while (t != NULL) {
+        if (t->state == TASK_STATE_WAIT_IRQ && (t->wait_irq & irq__bit) != 0) {
+            t->wait_irq = 0;
+            t->state = TASK_STATE_RUNNABLE;
+        }
+        t = t->next;
+    }
+}
+
+void task_wait_irq(uint16_t irq_bits) {
+    current_task->wait_irq = irq_bits;
+    current_task->state = TASK_STATE_WAIT_IRQ;
+    task_switch_next();
+}
+
 void task_switch_next_inner(task_t *next_task) {
     if (task_locked) {
         return; // don't switch while the task is locked
@@ -70,6 +106,10 @@ void task_switch_next_inner(task_t *next_task) {
     }
     task_t *previous_task = current_task;
     current_task = next_task;
+    if (previous_task->state == TASK_STATE_RUNNING) {
+        previous_task->state = TASK_STATE_RUNNABLE;
+    }
+    current_task->state = TASK_STATE_RUNNING;
     // switch task
     switch_task(previous_task == NULL ? NULL : &previous_task->task_registers, current_task->task_registers);
 }
@@ -78,34 +118,53 @@ void task_start_first() {
     task_switch_next_inner(first_task);
 }
 
+task_t *task_first_runnable() {
+    task_t *next_task = current_task;
+    bool looped = false;
+    if (next_task == idle_task || next_task->next == NULL) {
+        looped = true;
+        next_task = first_task;
+    } else {
+        next_task = current_task->next;
+    }
+    do {
+        if (!looped && next_task == NULL) {
+            looped = true;
+            next_task = first_task;
+        }
+        if (next_task == NULL) {
+            break;
+        }
+        if (next_task->state == TASK_STATE_RUNNABLE) {
+            return next_task;
+        }
+        next_task = next_task->next;
+    } while (next_task != current_task);
+    if (current_task->state == TASK_STATE_RUNNING)
+        return current_task;
+    return idle_task;
+}
+
 void task_switch_next() {
     if (current_task == NULL) {
         return;
     }
-    task_switch_next_inner(current_task->next == NULL ? first_task : current_task->next);
+    task_switch_next_inner(task_first_runnable());
 }
 
-uint32_t task_spawn(task_entrypoint entrypoint, void *entry_data) {
+task_t *task_create(task_entrypoint entrypoint, void *entry_data) {
     task_t *new_task = malloc(sizeof(task_t));
     memset((uint8_t *) new_task, 0, sizeof(task_t));
     new_task->tid = last_tid++;
+    new_task->state = TASK_STATE_RUNNABLE;
 
     new_task->stack = pmm_get_pages(16);
     new_task->stack_page_count = 16;
     // todo check for null
 
-
-    if (first_task == NULL) {
-        // first task
-        first_task = new_task;
-    } else {
-        last_task->next = new_task;
-    }
-    last_task = new_task;
-
     // prepare stack
     // cdecl format
-    task_stack_start* stack = (task_stack_start *) (stack_end(new_task) - sizeof(task_stack_start));
+    task_stack_start *stack = (task_stack_start *) (stack_end(new_task) - sizeof(task_stack_start));
     memset((uint8_t *) stack, 0, sizeof(task_stack_start));
     // setup isr return frame
     stack->isr_registers.cs = 0x08; // todo proper gdt setup
@@ -124,6 +183,23 @@ uint32_t task_spawn(task_entrypoint entrypoint, void *entry_data) {
     new_task->task_registers = &stack->task_registers;
 
     new_task->present = true;
+    return new_task;
+
+}
+
+void task_init() {
+    idle_task = task_create(task_idle, NULL);
+}
+
+uint32_t task_spawn(task_entrypoint entrypoint, void *entry_data) {
+    task_t *new_task = task_create(entrypoint, entry_data);
+    if (first_task == NULL) {
+        // first task
+        first_task = new_task;
+    } else {
+        last_task->next = new_task;
+    }
+    last_task = new_task;
     return new_task->tid;
 }