[MULTITASKING] Context switching and scheduler

kernel/proc/thread.c

@@ -0,0 +1,47 @@
+#include <thread.h>
+#include <stdint.h>
+#include <mem.h>
+#include <list.h>
+#include <debug.h>
+
+thread_t *current_thread = 0;
+
+uint64_t tid = 1;
+
+
+thread_t *new_thread(void (*func)(void))
+{
+  // Set up original stack of thread
+  thread_stack_t *stack = kcalloc(1, sizeof(thread_stack_t));
+  thread_t *th = &stack->tcb;
+
+  stack->function_address = (uint64_t)func;
+  stack->RBP = (uint64_t)&stack->zero_frame;
+
+  th->tid = tid++;
+  th->state = THREAD_STATE_READY;
+  th->stack_pointer = (uint64_t)&stack->RBP;
+
+  LIST_INIT(th, ready_queue);
+
+  return th;
+}
+
+void switch_thread(thread_t *old, thread_t *new)
+{
+  set_current_thread(new);
+
+  uint64_t *old_stack = (old)?&old->stack_pointer:0;
+  swtch(old_stack, &new->stack_pointer);
+}
+
+void free_thread(thread_t *th)
+{
+  if(th->state == THREAD_STATE_RUNNING || th->state == THREAD_STATE_READY)
+  {
+    debug_error("Trying to free a live thread!\n");
+    for(;;);
+  }
+  thread_stack_t *stack = incptr(th, -offsetof(thread_stack_t, tcb));
+  kfree(stack);
+}