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chore: improve timer behaviour

This commit is contained in:
Rekai Nyangadzayi Musuka 2022-10-21 05:12:36 -03:00
parent d144973acf
commit 14bb2f6fbe
2 changed files with 20 additions and 16 deletions
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8
src/bus/io.zig
View File

@ -268,13 +268,13 @@ pub fn write(bus: *Bus, comptime T: type, address: u32, value: T) void {
0x0400_00DE => bus.dma._3.writeCntHigh(value), 0x0400_00DE => bus.dma._3.writeCntHigh(value),
// Timers // Timers
0x0400_0100 => bus.tim._0.writeCntLow(value), 0x0400_0100 => bus.tim._0.setReload(value),
0x0400_0102 => bus.tim._0.writeCntHigh(value), 0x0400_0102 => bus.tim._0.writeCntHigh(value),
0x0400_0104 => bus.tim._1.writeCntLow(value), 0x0400_0104 => bus.tim._1.setReload(value),
0x0400_0106 => bus.tim._1.writeCntHigh(value), 0x0400_0106 => bus.tim._1.writeCntHigh(value),
0x0400_0108 => bus.tim._2.writeCntLow(value), 0x0400_0108 => bus.tim._2.setReload(value),
0x0400_010A => bus.tim._2.writeCntHigh(value), 0x0400_010A => bus.tim._2.writeCntHigh(value),
0x0400_010C => bus.tim._3.writeCntLow(value), 0x0400_010C => bus.tim._3.setReload(value),
0x0400_010E => bus.tim._3.writeCntHigh(value), 0x0400_010E => bus.tim._3.writeCntHigh(value),
0x0400_0110 => {}, // Not Used 0x0400_0110 => {}, // Not Used

28
src/bus/timer.zig
View File

@ -33,7 +33,7 @@ fn Timer(comptime id: u2) type {
/// Read Only, Internal. Please use self.counter() /// Read Only, Internal. Please use self.counter()
_counter: u16, _counter: u16,
/// Write Only, Internal. Please use self.writeCntLow() /// Write Only, Internal. Please use self.setReload()
_reload: u16, _reload: u16,
/// Write Only, Internal. Please use self.WriteCntHigh() /// Write Only, Internal. Please use self.WriteCntHigh()
@ -56,18 +56,17 @@ fn Timer(comptime id: u2) type {
} }
pub fn counter(self: *const Self) u16 { pub fn counter(self: *const Self) u16 {
if (self.cnt.cascade.read()) if (self.cnt.cascade.read() or !self.cnt.enabled.read()) return self._counter;
return self._counter
else return self._counter +% @truncate(u16, (self.sched.now() - self._start_timestamp) / self.frequency());
return self._counter +% @truncate(u16, (self.sched.now() - self._start_timestamp) / self.frequency());
} }
pub fn writeCnt(self: *Self, word: u32) void { pub fn writeCnt(self: *Self, word: u32) void {
self.writeCntLow(@truncate(u16, word)); self.setReload(@truncate(u16, word));
self.writeCntHigh(@truncate(u16, word >> 16)); self.writeCntHigh(@truncate(u16, word >> 16));
} }
pub fn writeCntLow(self: *Self, halfword: u16) void { pub fn setReload(self: *Self, halfword: u16) void {
self._reload = halfword; self._reload = halfword;
} }
@ -77,13 +76,18 @@ fn Timer(comptime id: u2) type {
// If Timer happens to be enabled, It will either be resheduled or disabled // If Timer happens to be enabled, It will either be resheduled or disabled
self.sched.removeScheduledEvent(.{ .TimerOverflow = id }); self.sched.removeScheduledEvent(.{ .TimerOverflow = id });
if (!self.cnt.enabled.read() and new.enabled.read()) { if (self.cnt.enabled.read() and (new.cascade.read() or !new.enabled.read())) {
// Reload on Rising edge // Either through the cascade bit or the enable bit, the timer has effectively been disabled
self._counter = self._reload; // The Counter should hold whatever value it should have been at when it was disabled
self._counter +%= @truncate(u16, (self.sched.now() - self._start_timestamp) / self.frequency());
if (!new.cascade.read()) self.scheduleOverflow(0);
} }
// The counter is only reloaded on the rising edge of the enable bit
if (!self.cnt.enabled.read() and new.enabled.read()) self._counter = self._reload;
// If Timer is enabled and we're not cascading, we need to schedule an overflow event
if (new.enabled.read() and !new.cascade.read()) self.scheduleOverflow(0);
self.cnt.raw = halfword; self.cnt.raw = halfword;
} }