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Writes to a pit8253 timer control word always restart the timer.

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This commit is contained in:
Wilbert Pol 2008-12-11 11:41:37 +00:00
parent 7eaa676d90
commit 4f0f80255a
1 changed files with 7 additions and 14 deletions
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21
src/emu/machine/pit8253.c
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@ -62,7 +62,6 @@ struct pit8253_timer
emu_timer *updatetimer; /* MAME timer to process updates */ emu_timer *updatetimer; /* MAME timer to process updates */
UINT8 programmed; /* Has this counter been programmed by writing to the control word */
UINT16 value; /* current counter value ("CE" in Intel docs) */ UINT16 value; /* current counter value ("CE" in Intel docs) */
UINT16 latch; /* latched counter value ("OL" in Intel docs) */ UINT16 latch; /* latched counter value ("OL" in Intel docs) */
UINT16 count; /* new counter value ("CR" in Intel docs) */ UINT16 count; /* new counter value ("CR" in Intel docs) */
@ -652,8 +651,7 @@ static void update(const device_config *device, struct pit8253_timer *timer)
timer->last_updated = now; timer->last_updated = now;
} }
if ( timer->programmed ) simulate(device, timer, elapsed_cycles);
simulate(device, timer, elapsed_cycles);
} }
@ -886,16 +884,12 @@ WRITE8_DEVICE_HANDLER( pit8253_w )
else { else {
LOG1(("pit8253_write(): timer=%d bytes=%d mode=%d bcd=%d\n", (data >> 6) & 3, (data >> 4) & 3, (data >> 1) & 7,data & 1)); LOG1(("pit8253_write(): timer=%d bytes=%d mode=%d bcd=%d\n", (data >> 6) & 3, (data >> 4) & 3, (data >> 1) & 7,data & 1));
if ( ( CTRL_MODE(timer->control) != CTRL_MODE(data) ) || ! timer->programmed ) timer->control = (data & 0x3f);
{ timer->null_count = 1;
timer->control = (data & 0x3f); timer->wmsb = timer->rmsb = 0;
timer->null_count = 1; /* Phase 0 is always the phase after a mode control write */
timer->wmsb = timer->rmsb = 0; timer->phase = 0;
/* Phase 0 is always the phase after a mode control write */ set_output(device, timer, CTRL_MODE(timer->control) ? 1 : 0);
timer->phase = 0;
set_output(device, timer, CTRL_MODE(timer->control) ? 1 : 0);
timer->programmed = 1;
}
} }
} }
else else
@ -1081,7 +1075,6 @@ static device_start_err common_start( const device_config *device, int device_ty
state_save_register_device_item(device, timerno, timer->cycles_to_output); state_save_register_device_item(device, timerno, timer->cycles_to_output);
state_save_register_device_item(device, timerno, timer->last_updated.seconds); state_save_register_device_item(device, timerno, timer->last_updated.seconds);
state_save_register_device_item(device, timerno, timer->last_updated.attoseconds); state_save_register_device_item(device, timerno, timer->last_updated.attoseconds);
state_save_register_device_item(device, timerno, timer->programmed);
state_save_register_device_item(device, timerno, timer->clock); state_save_register_device_item(device, timerno, timer->clock);
} }