Modified the tick_handler interrupt routine in timer.s so that it no

longer calls reschedule() directly. It now calls sched_tick() so that
the scheduler can make it's own decisions relating to handling the timer
interrupt.

The reschedule() function now *actually* implements a basic round-robin
scheduling algorithm that iterates through the list of tasks. This is
still a temporary algorithm but at least it now includes *all* runnable
processes instead of switching back and forth between process 1 and 2.

1 files changed, 14 insertions, 4 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index dd75d47..8469005 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -48,6 +48,7 @@ struct task_state {
 } __attribute__((packed));
 
 struct task_struct *ctask;
+uint32_t ctaskn;
 struct task_state *cstate;
 
 static struct task_struct tasks[NRTASKS];
@@ -194,6 +195,7 @@ void sched_init(void) {
 
   create_proc(&_usrbin_start, (size_t) &_usrbin_size);
   create_proc(&_usrbin_start, (size_t) &_usrbin_size);
+  create_proc(&_usrbin_start, (size_t) &_usrbin_size);
 
   switch_to(0, &tasks[0]);
 }
@@ -221,12 +223,20 @@ void save_state(void) {
 }
 
 void reschedule(void) {
+  int i;
+  uint32_t n;
+
   if(ctask == NULL)
     return;
 
-  if(ctask == &tasks[0]) {
-    switch_to(1, &tasks[1]);
-  } else {
-    switch_to(0, &tasks[0]);
+  n = ctaskn;
+  for(i = 0; i < NRTASKS; i++) {
+    n = (n + 1) % NRTASKS;
+    if(tasks[n].pid)
+      switch_to(n, &tasks[n]);
   }
 }
+
+void sched_tick(void) {
+  reschedule();
+}