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Fixes to pit timer mode 0

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Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@783
This commit is contained in:
Sjoerd van der Berg 2003-03-22 08:52:20 +00:00
parent 02934f9676
commit 9a34d7bd32
1 changed files with 14 additions and 8 deletions
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22
src/hardware/timer.cpp
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@ -49,38 +49,44 @@ static PIT_Block pit[3];
static void PIT0_Event(void) {
PIC_ActivateIRQ(0);
PIC_AddEvent(PIT0_Event,pit[0].micro);
if (pit[0].mode!=0) PIC_AddEvent(PIT0_Event,pit[0].micro);
}
static void counter_latch(Bitu counter) {
/* Fill the read_latch of the selected counter with current count */
PIT_Block * p=&pit[counter];
Bit64s micro=PIC_MicroCount()-p->start;
switch (p->mode) {
case 0: /* Interrupt on Terminal Count */
/* Counter keeps on counting after passing terminal count */
micro%=p->micro;
p->read_latch=(Bit16u)(p->cntr-(((float)micro/(float)p->micro)*(float)p->cntr));
if (micro>p->micro) {
micro-=p->micro;
micro%=(Bit64u)(1000000/((float)PIT_TICK_RATE/(float)0x10000));
p->read_latch=(Bit16u)(0x10000-(((double)micro/(double)p->micro)*(double)0x10000));
} else {
p->read_latch=(Bit16u)(p->cntr-(((double)micro/(double)p->micro)*(double)p->cntr));
}
break;
case 2: /* Rate Generator */
micro%=p->micro;
p->read_latch=(Bit16u)(p->cntr-(((float)micro/(float)p->micro)*(float)p->cntr));
p->read_latch=(Bit16u)(p->cntr-(((double)micro/(double)p->micro)*(double)p->cntr));
break;
case 3: /* Square Wave Rate Generator */
micro%=p->micro;
micro*=2;
if (micro>p->micro) micro-=p->micro;
p->read_latch=(Bit16u)(p->cntr-(((float)micro/(float)p->micro)*(float)p->cntr));
p->read_latch=(Bit16u)(p->cntr-(((double)micro/(double)p->micro)*(double)p->cntr));
break;
case 4: /* Software Triggered Strobe */
if (micro>p->micro) p->read_latch=p->write_latch;
else p->read_latch=(Bit16u)(p->cntr-(((float)micro/(float)p->micro)*(float)p->cntr));
else p->read_latch=(Bit16u)(p->cntr-(((double)micro/(double)p->micro)*(double)p->cntr));
break;
default:
LOG(LOG_ERROR|LOG_PIT,"Illegal Mode %d for reading counter %d",p->mode,counter);
micro%=p->micro;
p->read_latch=(Bit16u)(p->cntr-(((float)micro/(float)p->micro)*(float)p->cntr));
p->read_latch=(Bit16u)(p->cntr-(((double)micro/(double)p->micro)*(double)p->cntr));
break;
}
}