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machine/6522via.cpp: Made input ports read transparently when corresponding interrupt flag is clear. (#10878)

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Massimiliano Zattera 2023-03-05 18:00:57 +01:00 committed by GitHub
parent 6d4ccd8b1e
commit a3cb33156e
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1 changed files with 9 additions and 20 deletions
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29
src/devices/machine/6522via.cpp
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@ -11,17 +11,6 @@
**********************************************************************/
/*
1999-Dec-22 PeT
vc20 random number generation only partly working
(reads (uninitialized) timer 1 and timer 2 counter)
timer init, reset, read changed
2017-Feb-15 Edstrom
Fixed shift registers to be more accurate, eg 50/50 duty cycle, latching
on correct edges and leading and trailing edges added + logging.
*/
#include "emu.h"
#include "6522via.h"
@ -630,13 +619,13 @@ u8 via6522_device::read(offs_t offset)
{
case VIA_PB:
/* update the input */
if (PB_LATCH_ENABLE(m_acr) == 0)
if ((PB_LATCH_ENABLE(m_acr) != 0) && ((m_ifr & INT_CB1) != 0))
{
val = input_pb();
val = m_latch_b;
}
else
{
val = m_latch_b;
val = input_pb();
}
if (!machine().side_effects_disabled())
@ -648,13 +637,13 @@ u8 via6522_device::read(offs_t offset)
case VIA_PA:
/* update the input */
if (PA_LATCH_ENABLE(m_acr) == 0)
if ((PA_LATCH_ENABLE(m_acr) != 0) && ((m_ifr & INT_CA1) != 0))
{
val = input_pa();
val = m_latch_a;
}
else
{
val = m_latch_a;
val = input_pa();
}
if (!machine().side_effects_disabled())
@ -676,13 +665,13 @@ u8 via6522_device::read(offs_t offset)
case VIA_PANH:
/* update the input */
if (PA_LATCH_ENABLE(m_acr) == 0)
if ((PA_LATCH_ENABLE(m_acr) != 0) && ((m_ifr & INT_CA1) != 0))
{
val = input_pa();
val = m_latch_a;
}
else
{
val = m_latch_a;
val = input_pa();
}
break;