diff options
Diffstat (limited to 'src/dev/intel_8254_timer.cc')
| -rw-r--r-- | src/dev/intel_8254_timer.cc | 27 |
1 files changed, 21 insertions, 6 deletions
diff --git a/src/dev/intel_8254_timer.cc b/src/dev/intel_8254_timer.cc index 16d09f582..802dd44f5 100644 --- a/src/dev/intel_8254_timer.cc +++ b/src/dev/intel_8254_timer.cc @@ -147,13 +147,16 @@ Intel8254Timer::Counter::write(const uint8_t data) case MSB: count = (count & 0x00FF) | (data << 8); - period = count; + // In the RateGen or SquareWave modes, the timer wraps around and + // triggers on a value of 1, not 0. + if (mode == RateGen || mode == SquareWave) + period = count - 1; + else + period = count; + + if (period > 0) + event.setTo(period); - if (period > 0) { - DPRINTF(Intel8254Timer, "Timer set to curTick + %d\n", - count * event.interval); - event.schedule(curTick + count * event.interval); - } write_byte = LSB; break; } @@ -240,14 +243,26 @@ Intel8254Timer::Counter::CounterEvent::process() switch (counter->mode) { case InitTc: counter->output_high = true; + break; case RateGen: case SquareWave: + setTo(counter->period); break; default: panic("Unimplemented PITimer mode.\n"); } } +void +Intel8254Timer::Counter::CounterEvent::setTo(int clocks) +{ + if (clocks == 0) + panic("Timer can't be set to go off instantly.\n"); + DPRINTF(Intel8254Timer, "Timer set to curTick + %d\n", + clocks * interval); + schedule(curTick + clocks * interval); +} + const char * Intel8254Timer::Counter::CounterEvent::description() const { |