80486DX2-66/86Box-fork
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Two PIC fixes (implementation of freeze between the two INTA pulses for PC/XT, and find_best_interrupt() treating ISR'd cascaded slave IRQ's the same way as other IRQ's), and removed the incorrect IRQ latch reading.

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OBattler
2021-04-01 05:44:26 +02:00
parent 880f2f0304
commit 80095e7a30
1 changed files with 27 additions and 17 deletions
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44
src/pic.c
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@@ -168,28 +168,29 @@ find_best_interrupt(pic_t *dev)
int i, j;
int ret = -1;
#ifndef READ_LATCH
if (dev->interrupt != 0x17) {
/* We have an IRQ already latched, do not update status until it is unlatched in order to
avoid IRQ loss. */
ret = dev->interrupt;
return ret;
}
#endif
for (i = 0; i < 8; i++) {
j = (i + dev->priority) & 7;
b = 1 << j;
#ifdef OLD_CODE
s = (dev->icw4 & 0x10) && pic_slave_on(dev, j);
if ((dev->isr & b) && !dev->special_mask_mode && !s)
break;
if ((dev->state == 0) && ((dev->irr & ~dev->imr) & b) && (((dev->isr & b) == 0x00) || s)) {
if ((dev->state == 0) && ((dev->irr & ~dev->imr) & b) && (!(dev->isr & b) || s)) {
ret = j;
break;
}
if ((dev->isr & b) && !dev->special_mask_mode && s)
break;
#else
if (dev->isr & b)
break;
else if ((dev->state == 0) && ((dev->irr & ~dev->imr) & b)) {
ret = j;
break;
}
#endif
}
intr = dev->interrupt = (ret == -1) ? 0x17 : ret;
@@ -578,7 +579,8 @@ picint_common(uint16_t num, int level, int set)
}
}
update_pending();
if (!(pic.interrupt & 0x20) && !(pic2.interrupt & 0x20))
update_pending();
}
@@ -618,6 +620,8 @@ pic_irq_ack_read(pic_t *dev, int phase)
if (dev != NULL) {
if (phase == 0) {
dev->interrupt |= 0x20; /* Freeze it so it still takes interrupts but they do not
override the one currently being processed. */
pic_acknowledge(dev);
if (pic_slave_on(dev, intr))
dev->data_bus = pic_irq_ack_read(dev->slaves[intr], phase);
@@ -674,11 +678,15 @@ picinterrupt()
int i, ret = -1;
if (pic.int_pending) {
if (pic_slave_on(&pic, pic.interrupt) && !pic.slaves[pic.interrupt]->int_pending) {
/* If we are on AT, IRQ 2 is pending, and we cannot find a pending IRQ on PIC 2, fatal out. */
fatal("IRQ %i pending on AT without a pending IRQ on PIC %i (normal)\n", pic.interrupt, pic.interrupt);
exit(-1);
return -1;
if (pic_slave_on(&pic, pic.interrupt)) {
if (!pic.slaves[pic.interrupt]->int_pending) {
/* If we are on AT, IRQ 2 is pending, and we cannot find a pending IRQ on PIC 2, fatal out. */
fatal("IRQ %i pending on AT without a pending IRQ on PIC %i (normal)\n", pic.interrupt, pic.interrupt);
exit(-1);
return -1;
}
pic.interrupt |= 0x40; /* Mark slave pending. */
}
if ((pic.interrupt == 0) && (pit2 != NULL))
@@ -690,7 +698,9 @@ picinterrupt()
pic.ack_bytes = (pic.ack_bytes + 1) % (pic_i86_mode(&pic) ? 2 : 3);
if (pic.ack_bytes == 0) {
pic.interrupt = pic2.interrupt = 0x17;
if (pic.interrupt & 0x40)
pic2.interrupt = 0x17;
pic.interrupt = 0x17;
update_pending();
}
}