diff --git a/alloc.ccp b/alloc.ccp
index dc3e6f8..bed497c 100644
--- a/alloc.ccp
+++ b/alloc.ccp
@@ -179,7 +179,7 @@ Thread *Memory::alloc_thread ():
 	ret->pc = 0
 	ret->sp = 0
 	Thread_arch_init (ret)
-	ret->sleep = 0
+	ret->sleep_count = ~0
 	ret->flags = 0
 	ret->schedule_prev = NULL
 	ret->schedule_next = NULL
diff --git a/boot-programs/lcd.ccp b/boot-programs/lcd.ccp
index 214135a..6cf2255 100644
--- a/boot-programs/lcd.ccp
+++ b/boot-programs/lcd.ccp
@@ -37,97 +37,53 @@ static void set_backlight (bool state):
 		PWM_CTR (0) = 0x3f
 		GPIO_GPDR (2) &= ~PWM_ENABLE
 
-// Write to a register.  Value must be in range [0, 0xff].
-static void write_reg (unsigned reg, unsigned value):
-	unsigned data = (reg << 0xa) | 0x200 | value
-	GPIO_GPDR (2) |= SPEN
-	GPIO_GPDR (2) = (GPIO_GPDR (2) & ~SPDA) | SPCK
-	GPIO_GPDR (2) &= ~SPEN
-	udelay(25)
-	for unsigned i = 0; i < 16; ++i:
-		GPIO_GPDR (2) &= ~SPCK
-		if data & 0x8000:
-			GPIO_GPDR (2) |= SPDA
-		else:
-			GPIO_GPDR (2) &= ~SPDA
-		udelay (25)
-		GPIO_GPDR (2) |= SPCK
-		udelay (25)
-		data <<= 1
-	GPIO_GPDR (2) |= SPEN
-	udelay(200)
-
-static void lcd_enable ():
-	udelay (50)
-	GPIO_GPDR (2) &= ~LCD_RET
-	udelay(150000)
-	GPIO_GPDR (2) |= LCD_RET
-	udelay(10000)
-	// These values have been copied from the linux source.
-	// I have no idea what they do.
-	write_reg (0x00, 0x03)
-	write_reg (0x01, 0x40)
-	write_reg (0x02, 0x11)
-	write_reg (0x03, 0xcd)
-	write_reg (0x04, 0x32)
-	write_reg (0x05, 0x0e)
-	write_reg (0x07, 0x03)
-	write_reg (0x08, 0x08)
-	write_reg (0x09, 0x32)
-	write_reg (0x0A, 0x88)
-	write_reg (0x0B, 0xc6)
-	write_reg (0x0C, 0x20)
-	write_reg (0x0D, 0x20)
-	set_backlight (true)
-
-static void lcd_disable ():
-	write_reg (0x00, 0x03)
-	set_backlight (false)
-
 static void reset ():
-	gpio_as_pwm ()
-	gpio_as_lcd_master ()
-
-	GPIO_GPDR (2) &= ~PWM_ENABLE
-	PWM_CTR (0) = 0x3f
 	PWM_PER (0) = 300
-	pwm_set_duty (0, 300)
-	pwm_set_full_duty (0)
+	set_backlight (false)
 
 	// initialize things.
 	GPIO_GPIER (2) &= ~(PWM_ENABLE | LCD_RET | SPEN | SPCK | SPDA)
 	GPIO_GPDIR (2) |= PWM_ENABLE | LCD_RET | SPEN | SPCK | SPDA
 	udelay (50)
 	GPIO_GPDR (2) &= ~LCD_RET
-	udelay (150000)
+	ddelay (2)
 	GPIO_GPDR (2) |= LCD_RET
-	udelay (10000)
-	lcd_enable ()
+	ddelay (1)
 
 	// For now, support only 16 bpp.
 	// Screen is 800x480 tft.
+	unsigned h = 800, v = 480, hs = 80, vs = 20, fps = 60, Bpp = 2
 	LCD_CTRL = LCD_CTRL_BPP_16 | LCD_CTRL_BST_16
-	LCD_VSYNC = 20
-	LCD_HSYNC = 80
-	LCD_DAV = (20 << 16) | 500
-	LCD_DAH = (80 << 16) | 880
-	LCD_VAT = (880 << 16) | 500
-	//LCD_CFG = MODE_TFT_GEN | PCLK_N | VSYNC_N
+	LCD_VSYNC = vs
+	LCD_HSYNC = hs
+	LCD_DAV = (vs << 16) | (vs + v)
+	LCD_DAH = (hs << 16) | (hs + h)
+	LCD_VAT = ((hs + h) << 16) | (vs + v)
+	#define MODE_TFT_GEN 0
+	#define PCLK_N (1 << 10)
+	#define VSYNC_N (1 << 8)
+	LCD_CFG = MODE_TFT_GEN | PCLK_N | VSYNC_N
 
-	// Stop lcd.
-	CPM_MSCR |= 1 << 7
+	cpm_stop_lcd ()
 
-	unsigned pclk = 60 * (800 * 3 + 80) * 500
 	unsigned pllout = cpm_get_pllout ()
-	CPM_CFCR2 = pllout / pclk - 1
-	unsigned v = pllout / (pclk * 4) - 1
-	while v < 0xf && pllout / (v + 1) > 150000000:
-		++v
-	CPM_CFCR = (CPM_CFCR & ~CPM_CFCR_LFR_MASK) | (v << CPM_CFCR_LFR_BIT) | CPM_CFCR_UPE
+	unsigned pixclock = fps * (hs + h) * (vs + v)
+	CPM_CFCR2 = pllout / pixclock - 1
+
+	unsigned val = pllout / (pixclock * 4) - 1
+	while val < 0xf && pllout / (val + 1) > 150000000:
+		++val
+	cpm_set_lcdclk_div (val)
+	CPM_CFCR |= CPM_CFCR_UPE
+
+	cpm_start_lcd ()
 
-	// Start lcd.
-	CPM_MSCR &= ~(1 << 7)
 	udelay (1000)
+	//LCD_DA0 = framebuffer
+	unsigned frame_size = v * h * Bpp
+	LCD_CMD0 = LCD_CMD_SOFINT | LCD_CMD_EOFINT | (frame_size << LCD_CMD_LEN_BIT)
+	lcd_set_ena ()
+	lcd_enable_eof_intr ()
 
 int main ():
 	map_gpio ()
@@ -136,19 +92,20 @@ int main ():
 	map_cpm ()
 
 	reset ()
-
-	while true:
-		set_backlight (false)
-		kdebug (0)
-		set_backlight (true)
-		kdebug (0)
-		schedule ()
+	register_interrupt (IRQ_LCD)
+	set_backlight (true)
 
 	while true:
 		Message msg
 		if !wait (&msg):
 			continue
 		switch msg.protected_data:
+			case IRQ_LCD:
+				kdebug (0)
+				LCD_STATE &= ~LCD_STATE_EOF
+				register_interrupt (IRQ_LCD)
+				// TODO: allow callback
+				break
 			case LCD_BACKLIGHT:
 				set_backlight (msg.data[0])
 				break
diff --git a/invoke.ccp b/invoke.ccp
index f220f30..4a5ca17 100644
--- a/invoke.ccp
+++ b/invoke.ccp
@@ -18,6 +18,7 @@
 
 #include "kernel.hh"
 
+// From user-provided, thus untrusted, data, find a capability.
 Capability *Memory::find_capability (unsigned code, bool *copy):
 	if !code:
 		return NULL
@@ -39,6 +40,7 @@ Capability *Memory::find_capability (unsigned code, bool *copy):
 				return c
 	return NULL
 
+// Try to deliver a message.
 bool Receiver::try_deliver ():
 	if !messages || !owner || !owner->is_waiting ():
 		return false
@@ -61,6 +63,7 @@ bool Receiver::try_deliver ():
 	owner->unwait ()
 	return true
 
+// Send a message to a receiver; try to deliver it immediately.
 bool Receiver::send_message (unsigned protected_data, Capability::Context *c):
 	bool tried_direct = false
 	if owner && owner->is_waiting () && (protected_data == reply_protected_data || !protected_only):
@@ -328,14 +331,19 @@ static void thread_invoke (unsigned target, unsigned protected_data, Capability:
 								thread->unrun ()
 					break
 				case CAP_THREAD_INFO_SLEEP:
-					value = &thread->sleep
+					value = &thread->sleep_count
+					if thread->flags & THREAD_FLAG_WAITING:
+						unsigned newval = (*value & ~c->data[3]) | (c->data[2] & c->data[3])
+						if *value == ~0 && newval != ~0:
+							thread->sleep ()
+						else if *value != ~0 && newval == ~0:
+							thread->unsleep ()
 					break
 				default:
 					value = Thread_arch_info (thread, c->data[1])
 					break
 			if value:
-				*value &= ~c->data[3]
-				*value |= c->data[2] & c->data[3]
+				*value = (*value & ~c->data[3]) | (c->data[2] & c->data[3])
 				reply_num (*value)
 			else:
 				reply_num (0)
@@ -655,19 +663,19 @@ static bool kernel_invoke (unsigned target, unsigned protected_data, Capability:
 		reply_receiver = (Receiver *)protected_data
 		reply_receiver->protected_only = !(target & (1 << CAP_RECEIVER_CALL_ASYNC))
 		Capability *c0 = c->cap[0]
-		if ((unsigned)c0->target & ~KERNEL_MASK) != 0:
-			Capability r
-			fill_cap (&r, protected_data, reply_receiver->reply_protected_data)
-			c->cap[0] = &r
-			c->copy[0] = true
-			c0->target->send_message (c0->protected_data, c)
-			r.invalidate ()
-			return true
-		else:
-			// Kernel call: don't create actual capablities.
-			c->cap[0] = NULL
-			kernel_invoke ((unsigned)c0->target, c0->protected_data, c, c0)
-			return true
+		if c0:
+			if ((unsigned)c0->target & ~KERNEL_MASK) != 0:
+				Capability r
+				fill_cap (&r, protected_data, reply_receiver->reply_protected_data)
+				c->cap[0] = &r
+				c->copy[0] = true
+				c0->target->send_message (c0->protected_data, c)
+				r.invalidate ()
+			else:
+				// Kernel call: don't create actual capablities.
+				c->cap[0] = NULL
+				kernel_invoke ((unsigned)c0->target, c0->protected_data, c, c0)
+		return true
 	if (target & (CAPTYPE_MASK | (1 << CAP_RECEIVER_REPLY))) == (CAPTYPE_RECEIVER | (1 << CAP_RECEIVER_REPLY)):
 		// This is a reply capability.
 		Receiver *r = (Receiver *)protected_data
@@ -717,4 +725,5 @@ bool Capability::invoke (Capability::Context *c):
 		// This is not a kernel capability: send a message to the receiver.
 		return target->send_message (protected_data, c)
 	// This is a kernel capability.  Use a function to allow optimized call capabilities.
+	reply_receiver = NULL
 	return kernel_invoke ((unsigned)target, protected_data, c, this)
diff --git a/iris.h b/iris.h
index af73b8e..e2a7769 100644
--- a/iris.h
+++ b/iris.h
@@ -18,6 +18,13 @@
 #ifndef __IRIS_H
 #define __IRIS_H
 
+// Without the standard library, we don't have this definition.
+// I preferred ((void*)0), but C++ has too strict type-checking to
+// make that work.
+#ifndef NULL
+#define NULL 0
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -501,9 +508,17 @@ static unsigned thread_sleep (Capability thread, unsigned value)
 	return thread_info (thread, CAP_THREAD_INFO_SLEEP, value, ~0);
 }
 
-static void my_sleep (unsigned value)
+static int my_sleep (unsigned value, Message *ret)
 {
-	call_n04 (__my_thread, CAP_THREAD_INFO, CAP_THREAD_INFO_SLEEP, value, ~0);
+	ret->data[0] = CAP_THREAD_INFO;
+	ret->data[1] = CAP_THREAD_INFO_SLEEP;
+	ret->data[2] = value;
+	ret->data[3] = ~0;
+	ret->cap[0] = 0;
+	ret->cap[1] = 0;
+	ret->cap[2] = 0;
+	ret->cap[3] = 0;
+	return call (__my_thread, ret);
 }
 
 static unsigned thread_get_sleep (Capability thread)
diff --git a/kernel.hhp b/kernel.hhp
index 9a7e579..061b678 100644
--- a/kernel.hhp
+++ b/kernel.hhp
@@ -33,11 +33,6 @@
 #define EXTERN extern
 #endif
 
-// Without the standard library, we don't have this definition.
-// I preferred ((void*)0), but C++ has too strict type-checking to
-// make that work.
-#define NULL 0
-
 struct Object_base
 struct Page
 struct Thread
@@ -73,8 +68,10 @@ struct Thread : public Object <Thread>:
 	unsigned pc, sp
 	Thread_arch arch
 	unsigned flags
-	unsigned sleep
+	unsigned sleep_count
 	Thread *schedule_prev, *schedule_next
+	void sleep ()
+	void unsleep ()
 	void run ()
 	void unrun ()
 	void wait ()
diff --git a/mips/entry.S b/mips/entry.S
index 1d55ed5..f9c883d 100644
--- a/mips/entry.S
+++ b/mips/entry.S
@@ -111,9 +111,6 @@ start_idle:			// 280
 	// Wait for the next interrupt, then the first thread will be scheduled.
 	// It is impractical to try to call schedule, because for that the
 	// idle task would need to own capabilities.
-	move $v0, $zero
-	syscall
-	nop
 1:	wait
 	b 1b
 	nop
@@ -221,7 +218,8 @@ save_regs:
 #ifndef NDEBUG
 	// Allow interrupts to set EPC and friends.
 	mfc0 $k0, $CP0_STATUS
-	andi $k0, $k0, 0xff00
+	li $k1, 0x1000ff00
+	and $k0, $k0, $k1
 	mtc0 $k0, $CP0_STATUS
 #endif
 
diff --git a/mips/init.ccp b/mips/init.ccp
index 3eae0dd..7872427 100644
--- a/mips/init.ccp
+++ b/mips/init.ccp
@@ -257,12 +257,14 @@ void init ():
 	GPIO_GPDIR (GPIO_USB_CLK_EN_PORT) |= 1 << GPIO_USB_CLK_EN
 	GPIO_GPDR (GPIO_USB_CLK_EN_PORT) |= 1 << GPIO_USB_CLK_EN
 
-	// Start the operating system timer.
-	unsigned latch = (JZ_EXTAL + (HZ>>1)) / HZ
+	// Start the operating system timer, and set it to give an interrupt immediately.
+	// This is better, because the kernel start with jumping into the idle task and
+	// waiting for the first interrupt.
+	unsigned latch = (JZ_EXTAL + (HZ >> 1)) / HZ
 	ost_disable_all ()
 	ost_set_mode (0, OST_TCSR_UIE | OST_TCSR_CKS_EXTAL)
 	ost_set_reload (0, latch)
-	ost_set_count (0, latch)
+	ost_set_count (0, 0)
 	ost_set_mode (0, OST_TCSR_UIE | OST_TCSR_CKS_EXTAL)
 	ost_enable_channel (0)
 	intc_unmask_irq (IRQ_OST0)
diff --git a/mips/interrupts.ccp b/mips/interrupts.ccp
index 17b3b5b..b01d174 100644
--- a/mips/interrupts.ccp
+++ b/mips/interrupts.ccp
@@ -19,11 +19,40 @@
 #define ARCH
 #include "../kernel.hh"
 
+static void handle_exit (Thread *old_current):
+	if !current:
+		schedule ()
+		if !current:
+			current = &idle
+	if old_current == current:
+		return
+	if current != &idle:
+		if (Memory *)asids[current->address_space->arch.asid] != current->address_space:
+			if asids[0]:
+				current->address_space->arch.asid = asids[0]
+				asids[0] = asids[asids[0]]
+			else:
+				static unsigned random = 1
+				current->address_space->arch.asid = random
+				// Overwrite used asid, so flush those values from tlb.
+				flush_tlb (random)
+				++random
+				if random >= 64:
+					random = 1
+			asids[current->address_space->arch.asid] = (unsigned)current->address_space
+	cp0_set (CP0_ENTRY_HI, current->address_space->arch.asid)
+	directory = current->address_space->arch.directory
+	if current->flags & THREAD_FLAG_PRIV:
+		cp0_set (CP0_STATUS, 0x1000ff13)
+	else:
+		cp0_set (CP0_STATUS, 0x0000ff13)
+
 /// A TLB miss has occurred.  This is the slow version.  It is only used
 /// when k0 or k1 is not 0, or when an error occurs.
 /// Otherwise, the ultra-fast code in entry.S is used.
 Thread *tlb_refill ():
 	//panic (0x88776655, "TLB refill")
+	Thread *old_current = current
 	if !directory:
 		panic (0x44449999, "No directory")
 	unsigned EntryHi
@@ -41,11 +70,13 @@ Thread *tlb_refill ():
 	cp0_set (CP0_ENTRY_LO0, t[idx])
 	cp0_set (CP0_ENTRY_LO1, t[idx + 1])
 	__asm__ volatile ("tlbwr")
+	handle_exit (old_current)
 	return current
 
 /// An interrupt which is not an exception has occurred.
 Thread *interrupt ():
 	//panic (0x88877722, "Interrupt")
+	Thread *old_current = current
 	//dbg_send (INTC_IPR)
 	unsigned ipr = INTC_IPR
 	for unsigned i = 0; i < 32; ++i:
@@ -68,6 +99,7 @@ Thread *interrupt ():
 		ost_clear_uf (0)
 		intc_ack_irq (IRQ_OST0)
 		timer_interrupt ()
+	handle_exit (old_current)
 	return current
 
 void flush_tlb (unsigned asid):
@@ -87,10 +119,9 @@ static void arch_invoke ():
 	Thread *caller = current
 	target = caller->address_space->find_capability (caller->arch.v0, &wait)
 	if !target:
-		// TODO: there must be no action here.  This is just because the rest doesn't work yet.
-		dbg_send (3, 2)
+		// There must be no action here.
+		//dbg_send (3, 2)
 		//dbg_send (caller->arch.v0)
-		schedule ()
 		// Calling an invalid capability always fails.
 		caller->arch.v0 = 0
 	else:
@@ -108,35 +139,10 @@ static void arch_invoke ():
 		caller->arch.v0 = target->invoke (&c) ? 1 : 0
 	if caller != current && caller != &idle && (caller->flags & (THREAD_FLAG_RUNNING | THREAD_FLAG_WAITING)) == THREAD_FLAG_RUNNING:
 		current = caller
-	else if !current:
-		schedule ()
-		if !current:
-			current = &idle
-	if caller != current:
-		if (Memory *)asids[current->address_space->arch.asid] != current->address_space:
-			if asids[0]:
-				current->address_space->arch.asid = asids[0]
-				asids[0] = asids[asids[0]]
-			else:
-				static unsigned random = 1
-				current->address_space->arch.asid = random
-				// Overwrite used asid, so flush those values from tlb.
-				flush_tlb (random)
-				++random
-				if random >= 64:
-					random = 1
-			asids[current->address_space->arch.asid] = (unsigned)current->address_space
-		cp0_set (CP0_ENTRY_HI, current->address_space->arch.asid)
-		directory = current->address_space->arch.directory
-		unsigned status
-		cp0_get (CP0_STATUS, status)
-		status &= 0x0fffffff
-		if current->flags & THREAD_FLAG_PRIV:
-			status |= 0x10000000
-		cp0_set (CP0_STATUS, status | 0x13)
 
 /// A general exception has occurred.
 Thread *exception ():
+	Thread *old_current = current
 	unsigned cause
 	cp0_get (CP0_CAUSE, cause)
 	switch (cause >> 2) & 0x1f:
@@ -220,9 +226,12 @@ Thread *exception ():
 			panic (0xf5223344, "Reserved exception code")
 		default:
 			panic (0xf6223344, "Impossible exception code")
+	handle_exit (old_current)
 	return current
 
 /// There's a cache error.  Big trouble.  Probably not worth trying to recover.
 Thread *cache_error ():
 	panic (0x33333333, "cache error")
+	Thread *old_current = current
+	handle_exit (old_current)
 	return current
diff --git a/mips/jz4730.hhp b/mips/jz4730.hhp
index c8fb69c..7722668 100644
--- a/mips/jz4730.hhp
+++ b/mips/jz4730.hhp
@@ -23,6 +23,7 @@
 
 // Main clock, for cpu, serial port, and with divisors for most other hardware
 #define JZ_EXTAL 3686400
+//#define JZ_EXTAL 3072000
 // RTC clock
 #define RTC_CLOCK 32768
 
@@ -2311,8 +2312,9 @@ static __inline__ void udelay (unsigned us):
 			GPIO_GPDR (0) = GPIO_GPDR (0)
 
 #ifndef __KERNEL
-static __inline__ void mdelay (unsigned ms):
-	my_sleep ((ms + 99) / 100)
+static __inline__ void ddelay (unsigned ds):
+	Message m
+	my_sleep (ds, &m)
 #endif
 
 /***************************************************************************
diff --git a/mips/test.ccp b/mips/test.ccp
index f081b94..e47ceb8 100644
--- a/mips/test.ccp
+++ b/mips/test.ccp
@@ -109,6 +109,6 @@ void dbg_send (unsigned code, unsigned bits):
 		dbg_led (false, false, false)
 		dbg_sleep (200)
 	dbg_led (true, true, false)
-	dbg_sleep (500)
+	dbg_sleep (50)
 	dbg_led (false, false, false)
-	dbg_sleep (500)
+	dbg_sleep (50)
diff --git a/schedule.ccp b/schedule.ccp
index b052c70..fe3d667 100644
--- a/schedule.ccp
+++ b/schedule.ccp
@@ -33,18 +33,29 @@ static void unrun_thread (Thread *thread):
 		first_scheduled = thread->schedule_next
 	if thread->schedule_next:
 		thread->schedule_next->schedule_prev = thread->schedule_prev
-	if thread->sleep:
-		thread->schedule_next = first_sleeper
-		thread->schedule_prev = NULL
-		if thread->schedule_next:
-			thread->schedule_next->schedule_prev = thread
-		first_sleeper = thread
+
+void Thread::sleep ():
+	schedule_next = first_sleeper
+	if schedule_next:
+		schedule_next->schedule_prev = this
+	schedule_prev = NULL
+	first_sleeper = this
+
+void Thread::unsleep ():
+	if schedule_next:
+		schedule_next->schedule_prev = schedule_prev
+	if schedule_prev:
+		schedule_prev->schedule_next = schedule_next
+	else:
+		first_sleeper = schedule_next
 
 void Thread::run ():
 	if flags & THREAD_FLAG_RUNNING:
 		return
 	flags |= THREAD_FLAG_RUNNING
 	if flags & THREAD_FLAG_WAITING:
+		if sleep_count != ~0:
+			sleep ()
 		return
 	run_thread (this)
 
@@ -53,41 +64,47 @@ void Thread::unrun ():
 		return
 	flags &= ~THREAD_FLAG_RUNNING
 	if flags & THREAD_FLAG_WAITING:
+		if sleep_count != ~0:
+			unsleep ()
 		return
 	unrun_thread (this)
 
+void Thread::unwait ():
+	if !(flags & THREAD_FLAG_WAITING):
+		return
+	flags &= ~THREAD_FLAG_WAITING
+	if sleep_count != ~0:
+		unsleep ()
+	if flags & THREAD_FLAG_RUNNING:
+		run_thread (this)
+
+static void sleep_tick (Thread *thread):
+	if !thread->sleep_count:
+		thread->unwait ()
+		// Time-out: let the thread know with a special message.
+		Capability::Context c
+		for unsigned i = 0; i < 4; ++i:
+			c.data[i] = 0
+			c.cap[i] = NULL
+			c.copy[i] = false
+		Thread_arch_receive (thread, ~0, &c)
+		// Fall through to let sleep be set to ~0, so the next wait will be infinitely long again.
+	--thread->sleep_count
+
 void Thread::wait ():
 	if flags & THREAD_FLAG_WAITING:
 		return
 	if flags & THREAD_FLAG_RUNNING:
 		unrun_thread (this)
 	flags |= THREAD_FLAG_WAITING
+	if sleep_count != ~0:
+		sleep ()
 	// Try to receive a message from a Receiver immediately.
 	for Receiver *r = receivers; r; r = r->next_owned:
 		if r->try_deliver ():
-			break
-
-void Thread::unwait ():
-	if !(flags & THREAD_FLAG_WAITING):
-		return
-	flags &= ~THREAD_FLAG_WAITING
-	if flags & THREAD_FLAG_RUNNING:
-		run_thread (this)
-
-void timer_interrupt ():
-	//panic (0x88877744, "Timer interrupt")
-	Thread *thread, *next
-	for thread = first_sleeper; thread; thread = next:
-		next = thread->next
-		if !--thread->sleep:
-			if thread->flags & THREAD_FLAG_WAITING:
-				thread->unwait ()
-			else:
-				run_thread (thread)
-	//#ifndef NDEBUG
-	//static bool ledstate = false
-	//dbg_led (false, false, ledstate = !ledstate)
-	//#endif
+			return
+	if sleep_count != ~0:
+		sleep_tick (this)
 
 void schedule ():
 	Thread *old = current
@@ -95,3 +112,17 @@ void schedule ():
 		current = current->schedule_next
 	if !current:
 		current = first_scheduled
+		if !current:
+			current = &idle
+
+void timer_interrupt ():
+	//panic (0x88877744, "Timer interrupt")
+	Thread *thread, *next
+	for thread = first_sleeper; thread; thread = next:
+		next = thread->next
+		sleep_tick (thread)
+	schedule ()
+	//#ifndef NDEBUG
+	//static bool ledstate = false
+	//dbg_led (false, false, ledstate = !ledstate)
+	//#endif