Add helper functions to convert timer irqs to milliseconds.

Add ticks_to_ms() and ticks_from_ms() helpers.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

6 files changed, 22 insertions, 11 deletions

diff --git a/src/clock.c b/src/clock.c
index b9a708b..2f2ca07 100644
--- a/src/clock.c
+++ b/src/clock.c
@@ -94,8 +94,7 @@ clock_setup(void)
     u32 seconds = bcd2bin(inb_cmos(CMOS_RTC_SECONDS));
     u32 minutes = bcd2bin(inb_cmos(CMOS_RTC_MINUTES));
     u32 hours = bcd2bin(inb_cmos(CMOS_RTC_HOURS));
-    u32 ticks = (hours * 60 + minutes) * 60 + seconds;
-    ticks = ((u64)ticks * PIT_TICK_RATE) / PIT_TICK_INTERVAL;
+    u32 ticks = ticks_from_ms(((hours * 60 + minutes) * 60 + seconds) * 1000);
     SET_BDA(timer_counter, ticks);
 
     // Setup Century storage
diff --git a/src/timer.c b/src/timer.c
index 87df97b..0fd0194 100644
--- a/src/timer.c
+++ b/src/timer.c
@@ -198,6 +198,21 @@ calc_future_tsc_usec(u32 usecs)
  * IRQ based timer
  ****************************************************************/
 
+// Return the number of milliseconds in 'ticks' number of timer irqs.
+u32
+ticks_to_ms(u32 ticks)
+{
+    return DIV_ROUND_UP(PIT_TICK_INTERVAL * 1000 * ticks, PIT_TICK_RATE);
+}
+
+// Return the number of timer irqs in 'ms' number of milliseconds.
+u32
+ticks_from_ms(u32 ms)
+{
+    u32 kticks = DIV_ROUND_UP((u64)ms * PIT_TICK_RATE, PIT_TICK_INTERVAL);
+    return DIV_ROUND_UP(kticks, 1000);
+}
+
 // Calculate the timer value at 'count' number of full timer ticks in
 // the future.
 u32
@@ -212,9 +227,7 @@ calc_future_timer(u32 msecs)
 {
     if (!msecs)
         return GET_BDA(timer_counter);
-    u32 kticks = DIV_ROUND_UP((u64)msecs * PIT_TICK_RATE, PIT_TICK_INTERVAL);
-    u32 ticks = DIV_ROUND_UP(kticks, 1000);
-    return calc_future_timer_ticks(ticks);
+    return calc_future_timer_ticks(ticks_from_ms(msecs));
 }
 
 // Check if the given timer value has passed.
diff --git a/src/usb-ehci.c b/src/usb-ehci.c
index e1e659b..c1638e4 100644
--- a/src/usb-ehci.c
+++ b/src/usb-ehci.c
@@ -15,7 +15,6 @@
 #include "biosvar.h" // GET_LOWFLAT
 #include "usb-uhci.h" // uhci_setup
 #include "usb-ohci.h" // ohci_setup
-#include "pit.h" // PIT_TICK_RATE
 
 struct usb_ehci_s {
     struct usb_s usb;
@@ -427,7 +426,7 @@ ehci_alloc_intr_pipe(struct usbdevice_s *usbdev
     int maxpacket = epdesc->wMaxPacketSize;
     // Determine number of entries needed for 2 timer ticks.
     int ms = 1<<frameexp;
-    int count = DIV_ROUND_UP(PIT_TICK_INTERVAL * 1000 * 2, PIT_TICK_RATE * ms);
+    int count = DIV_ROUND_UP(ticks_to_ms(2), ms);
     struct ehci_pipe *pipe = memalign_low(EHCI_QH_ALIGN, sizeof(*pipe));
     struct ehci_qtd *tds = memalign_low(EHCI_QTD_ALIGN, sizeof(*tds) * count);
     void *data = malloc_low(maxpacket * count);
diff --git a/src/usb-ohci.c b/src/usb-ohci.c
index f3a3b3b..b2e1d7f 100644
--- a/src/usb-ohci.c
+++ b/src/usb-ohci.c
@@ -11,7 +11,6 @@
 #include "pci_regs.h" // PCI_BASE_ADDRESS_0
 #include "usb.h" // struct usb_s
 #include "biosvar.h" // GET_LOWFLAT
-#include "pit.h" // PIT_TICK_RATE
 
 #define FIT                     (1 << 31)
 
@@ -328,7 +327,7 @@ ohci_alloc_intr_pipe(struct usbdevice_s *usbdev
     int maxpacket = epdesc->wMaxPacketSize;
     // Determine number of entries needed for 2 timer ticks.
     int ms = 1<<frameexp;
-    int count = DIV_ROUND_UP(PIT_TICK_INTERVAL * 1000 * 2, PIT_TICK_RATE * ms)+1;
+    int count = DIV_ROUND_UP(ticks_to_ms(2), ms) + 1;
     struct ohci_pipe *pipe = malloc_low(sizeof(*pipe));
     struct ohci_td *tds = malloc_low(sizeof(*tds) * count);
     void *data = malloc_low(maxpacket * count);
diff --git a/src/usb-uhci.c b/src/usb-uhci.c
index e77f5c1..5fa05a8 100644
--- a/src/usb-uhci.c
+++ b/src/usb-uhci.c
@@ -12,7 +12,6 @@
 #include "pci_regs.h" // PCI_BASE_ADDRESS_4
 #include "usb.h" // struct usb_s
 #include "biosvar.h" // GET_LOWFLAT
-#include "pit.h" // PIT_TICK_RATE
 
 struct usb_uhci_s {
     struct usb_s usb;
@@ -283,7 +282,7 @@ uhci_alloc_intr_pipe(struct usbdevice_s *usbdev
     int maxpacket = epdesc->wMaxPacketSize;
     // Determine number of entries needed for 2 timer ticks.
     int ms = 1<<frameexp;
-    int count = DIV_ROUND_UP(PIT_TICK_INTERVAL * 1000 * 2, PIT_TICK_RATE * ms);
+    int count = DIV_ROUND_UP(ticks_to_ms(2), ms);
     count = ALIGN(count, 2);
     struct uhci_pipe *pipe = malloc_low(sizeof(*pipe));
     struct uhci_td *tds = malloc_low(sizeof(*tds) * count);
diff --git a/src/util.h b/src/util.h
index 15982e2..a91b7f8 100644
--- a/src/util.h
+++ b/src/util.h
@@ -282,6 +282,8 @@ void useRTC(void);
 void releaseRTC(void);
 
 // timer.c
+u32 ticks_to_ms(u32 ticks);
+u32 ticks_from_ms(u32 ms);
 void pmtimer_setup(u16 ioport);
 int check_tsc(u64 end);
 void timer_setup(void);