# HG changeset patch
# User John Tsiombikas <nuclear@member.fsf.org>
# Date 1313378278 -10800
# Node ID 0be4615594df271f76be24c33321877284a95846
# Parent  88a6c4e192f916e5bcc582e7e4cd47651f26c118
finally, runqueues, blocking, waking up, idle loop etc, all seem to work fine
on a single user process... Next up: try forking another one :)

diff -r 88a6c4e192f9 -r 0be4615594df src/klibc/assert.h
--- a/src/klibc/assert.h	Mon Aug 15 04:03:39 2011 +0300
+++ b/src/klibc/assert.h	Mon Aug 15 06:17:58 2011 +0300
@@ -5,7 +5,7 @@
 
 #define assert(x) \
 	if(!(x)) { \
-		panic("Kernel assertion failed: " #x "\n"); \
+		panic("Kernel assertion failed at " __FILE__ ":%d: " #x "\n", __LINE__); \
 	}
 
 #endif	/* ASSERT_H_ */
diff -r 88a6c4e192f9 -r 0be4615594df src/proc.c
--- a/src/proc.c	Mon Aug 15 04:03:39 2011 +0300
+++ b/src/proc.c	Mon Aug 15 06:17:58 2011 +0300
@@ -24,7 +24,13 @@
 void test_proc_end(void);
 
 static struct process proc[MAX_PROC];
-static int cur_pid;
+
+/* cur_pid:  pid of the currently executing process.
+ *           when we're in the idle process cur_pid will be 0.
+ * last_pid: pid of the last real process that was running, this should
+ *           never become 0. Essentially this defines the active kernel stack.
+ */
+static int cur_pid, last_pid;
 
 static struct task_state *tss;
 
@@ -121,7 +127,8 @@
 	/* add it to the scheduler queues */
 	add_proc(p->id);
 
-	cur_pid = p->id; /* make it current */
+	/* make it current */
+	set_current_pid(p->id);
 
 	/* execute a fake return from interrupt with the fake stack frame */
 	intr_ret(ifrm);
@@ -130,31 +137,43 @@
 
 void context_switch(int pid)
 {
-	struct process *prev, *new;
+	static struct process *prev, *new;
 
 	assert(get_intr_state() == 0);
+	assert(pid > 0);
+	assert(last_pid > 0);
 
-	if(cur_pid == pid) {
-		return;	/* nothing to be done */
-	}
-	prev = proc + cur_pid;
+	prev = proc + last_pid;
 	new = proc + pid;
 
-	/* push all registers onto the stack before switching stacks */
-	push_regs();
+	if(last_pid != pid) {
+		/* push all registers onto the stack before switching stacks */
+		push_regs();
 
-	prev->ctx.stack_ptr = switch_stack(new->ctx.stack_ptr);
+		prev->ctx.stack_ptr = switch_stack(new->ctx.stack_ptr);
 
-	/* restore registers from the new stack */
-	pop_regs();
+		/* restore registers from the new stack */
+		pop_regs();
 
-	/* switch to the new process' address space */
-	set_pgdir_addr(new->ctx.pgtbl_paddr);
+		/* switch to the new process' address space */
+		set_pgdir_addr(new->ctx.pgtbl_paddr);
 
-	/* make sure we'll return to the correct kernel stack next time
-	 * we enter from userspace
-	 */
-	tss->esp0 = PAGE_TO_ADDR(new->kern_stack_pg) + KERN_STACK_SIZE;
+		/* make sure we'll return to the correct kernel stack next time
+		 * we enter from userspace
+		 */
+		tss->esp0 = PAGE_TO_ADDR(new->kern_stack_pg) + KERN_STACK_SIZE;
+	}
+
+	set_current_pid(new->id);
+}
+
+
+void set_current_pid(int pid)
+{
+	cur_pid = pid;
+	if(pid > 0) {
+		last_pid = pid;
+	}
 }
 
 int get_current_pid(void)
@@ -164,7 +183,7 @@
 
 struct process *get_current_proc(void)
 {
-	return cur_pid ? &proc[cur_pid] : 0;
+	return cur_pid > 0 ? &proc[cur_pid] : 0;
 }
 
 struct process *get_process(int pid)
diff -r 88a6c4e192f9 -r 0be4615594df src/proc.h
--- a/src/proc.h	Mon Aug 15 04:03:39 2011 +0300
+++ b/src/proc.h	Mon Aug 15 06:17:58 2011 +0300
@@ -47,6 +47,7 @@
 
 void context_switch(int pid);
 
+void set_current_pid(int pid);
 int get_current_pid(void);
 struct process *get_current_proc(void);
 struct process *get_process(int pid);
diff -r 88a6c4e192f9 -r 0be4615594df src/sched.c
--- a/src/sched.c	Mon Aug 15 04:03:39 2011 +0300
+++ b/src/sched.c	Mon Aug 15 06:17:58 2011 +0300
@@ -30,8 +30,15 @@
 	disable_intr();
 
 	if(EMPTY(&runq)) {
+		if(!get_current_proc()) {
+			/* we're already in the idle process, don't reenter it
+			 * or you'll fill up the stack very quickly.
+			 */
+			return;
+		}
+
 		idle_proc();
-		/* this won't return, it'll just wake up in an interrupt later */
+		return;
 	}
 
 	/* if the current process exhausted its timeslice,
@@ -88,6 +95,9 @@
 
 	p->state = STATE_BLOCKED;
 	p->wait_addr = wait_addr;
+
+	/* call the scheduler to give time to another process */
+	schedule();
 }
 
 /* wake up all the processes sleeping on this address */
@@ -124,9 +134,14 @@
 	struct intr_frame *ifrm = get_intr_frame();
 	end_of_irq(INTR_TO_IRQ(ifrm->inum));
 
+	set_current_pid(0);
+
 	/* make sure interrupts are enabled before halting */
-	enable_intr();
-	halt_cpu();
+	while(EMPTY(&runq)) {
+		enable_intr();
+		halt_cpu();
+		disable_intr();
+	}
 }
 
 
diff -r 88a6c4e192f9 -r 0be4615594df src/syscall.c
--- a/src/syscall.c	Mon Aug 15 04:03:39 2011 +0300
+++ b/src/syscall.c	Mon Aug 15 06:17:58 2011 +0300
@@ -55,6 +55,9 @@
 
 static int sys_sleep(int sec)
 {
-	printf("SYSCALL: sleep\n");
-	return -1;
+	printf("process %d will sleep for %d seconds\n", get_current_pid(), sec);
+
+	sleep(sec * 1000);
+
+	return 0;
 }
diff -r 88a6c4e192f9 -r 0be4615594df src/test_proc.S
--- a/src/test_proc.S	Mon Aug 15 04:03:39 2011 +0300
+++ b/src/test_proc.S	Mon Aug 15 06:17:58 2011 +0300
@@ -10,7 +10,7 @@
 
 	/* --- sleep for 5 seconds --- */
 	movl $SYS_SLEEP, %eax
-	movl $5, %ebx
+	movl $3, %ebx
 	int $SYSCALL_INT
 
 	jmp test_proc
diff -r 88a6c4e192f9 -r 0be4615594df src/timer.c
--- a/src/timer.c	Mon Aug 15 04:03:39 2011 +0300
+++ b/src/timer.c	Mon Aug 15 06:17:58 2011 +0300
@@ -136,11 +136,10 @@
 static void intr_handler(int inum)
 {
 	int istate;
-	struct process *cur_proc;
 
 	nticks++;
 
-	printf("TICKS: %d\n", nticks);
+	/*printf("TICKS: %d\n", nticks);*/
 
 	istate = get_intr_state();
 	disable_intr();
@@ -149,7 +148,7 @@
 	if(evlist) {
 		evlist->dt--;
 
-		while(evlist->dt <= 0) {
+		while(evlist && evlist->dt <= 0) {
 			struct timer_event *ev = evlist;
 			evlist = evlist->next;
 
@@ -160,12 +159,8 @@
 		}
 	}
 
-	if((cur_proc = get_current_proc())) {
-		/* if the timeslice of this process has expire, call the scheduler */
-		if(--cur_proc->ticks_left <= 0) {
-			schedule();
-		}
-	}
+	/* call the scheduler to decide if it's time to switch processes */
+	schedule();
 
 	set_intr_state(istate);
 }
diff -r 88a6c4e192f9 -r 0be4615594df src/timer.h
--- a/src/timer.h	Mon Aug 15 04:03:39 2011 +0300
+++ b/src/timer.h	Mon Aug 15 06:17:58 2011 +0300
@@ -1,12 +1,10 @@
 #ifndef _TIMER_H_
 #define _TIMER_H_
 
-typedef void (*timer_func_t)(void*);
-
 unsigned long nticks;
 
 void init_timer(void);
 
-int start_timer(unsigned long msec, timer_func_t cbfunc, void *cbarg);
+void sleep(unsigned long msec);
 
 #endif	/* _TIMER_H_ */