4 files changed, 43 insertions, 8 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 529db61..9f955d2 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -199,12 +199,25 @@ void reschedule(void) {
 
   n = ctaskn;
   while(1) {
-    n = (n + 1) % NRTASKS;
-    if(tasks[n].pid && tasks[n].state == TSTATE_RUNNING)
-      break;
-  }
+    /* check alarms and signals */
+    for(i = 0; i < NRTASKS; i++) {
+      if(tasks[i].alarm && tasks[i].alarm < ticks) {
+        tasks[i].alarm = 0;
+        tasks[i].signal |= 1 << (SIGALRM - 1);
+      }
+      if(tasks[i].signal && tasks[i].state == TSTATE_INTERRUPTIBLE)
+        tasks[i].state = TSTATE_RUNNING;
+    }
 
-  switch_to(n, &tasks[n]);
+    /* check if a process is ready to run */
+    for(i = 0; i < NRTASKS; i++) {
+      n = (n + 1) % NRTASKS;
+      if(tasks[n].pid && tasks[n].state == TSTATE_RUNNING) {
+        switch_to(n, &tasks[n]);
+        return;
+      }
+    }
+  }
 }
 
 void sched_tick(void) {
diff --git a/kernel/sys.c b/kernel/sys.c
index 20494de..c2256c1 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -36,12 +36,26 @@ void *sys_signal(int sig, void (*func)(int)) {
   if(sig == SIGKILL || sig == SIGSTOP)
     return NULL;
 
-  printk("Task %x registered new signal handler 0x%08x for signal %01x\n", ctask->pid, (uint32_t) func, sig);
   ctask->sig_handlers[sig] = func;
 
   return func;
 }
 
+int sys_alarm(unsigned int seconds) {
+  if(!seconds) {
+    ctask->alarm = 0;
+    return 0;
+  }
+
+  ctask->alarm = ticks + (seconds * 100);
+}
+
+int sys_pause(void) {
+  ctask->state = TSTATE_INTERRUPTIBLE;
+  reschedule();
+  return -1;
+}
+
 int sys_dummy(void) {
   return -ENOSYS;
 }
diff --git a/kernel/timer.s b/kernel/timer.s
index b96e1f1..6d95281 100644
--- a/kernel/timer.s
+++ b/kernel/timer.s
@@ -19,6 +19,8 @@ tick_handler:
   mov es, ax
   mov fs, ax
   mov gs, ax
+  ; save a pointer to the state information
+  mov ebx, esp
   ; handle the timer tick
   mov dword [ticked], 1
   inc dword [ticks]
@@ -31,7 +33,9 @@ tick_handler:
   ; if it isn't, call the scheduler
   call sched_tick
   ; handle any pending signals before returning to normal execution
+  push ebx
   call check_signals
+  add esp, 4
 .end:
   ; restore the data segment selectors
   pop ax
diff --git a/kernel/traps.s b/kernel/traps.s
index 36b3423..0a0d202 100644
--- a/kernel/traps.s
+++ b/kernel/traps.s
@@ -21,8 +21,8 @@ extern ticked
 ; too.
 
 %define ts_signal       6
-%define ts_sig_handlers 10
-%define ts_tss_esp0     142
+%define ts_sig_handlers 14
+%define ts_tss_esp0     146
 
 %macro SAVE 0
   pusha
@@ -323,6 +323,7 @@ check_signals:
   shl ebx, cl
   xor ebx, 0xFFFFFFFF
   and dword [eax+ts_signal], ebx
+  inc ecx
   mov ebx, ecx
   ; calculate offset to the handler function
   shl ecx, 2
@@ -374,7 +375,10 @@ check_signals:
   ret
 
 sigret:
+  mov ebx, esp
+  push ebx
   call check_signals
+  add esp, 4
   ; restore our original stack frame and reset the TSS's ESP0
   mov esp, [eax+ts_tss_esp0]
   mov dword [eax+ts_tss_esp0], 0xFFFFFFFF