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[CoCo 3] Fixed an issue clearing interrupts on the GIME implementation

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The normal way to acknowledge a GIME interrupt is by reading from $FF92/3.  However, the act of disabling interrupts by writing to the same registers will also do the trick, and we were not emulating this technique.

Thanks to Glen Hewlett and Tim Lindner for helping to identify this problem
This commit is contained in:
Nathan Woods 2017-03-19 17:37:57 -04:00
parent f1a1928505
commit bf2309aa29
2 changed files with 54 additions and 48 deletions
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94
src/mame/video/gime.cpp
View File

@ -624,15 +624,15 @@ uint8_t gime_base_device::read(offs_t offset)
switch(offset & 0xF0)
{
case 0x00:
data = read_gime_register(offset);
data = read_gime_register(offset); // $FF90 - $FF9F
break;
case 0x10:
data = read_mmu_register(offset);
data = read_mmu_register(offset); // $FFA0 - $FFAF
break;
case 0x20:
data = read_palette_register(offset);
data = read_palette_register(offset); // $FFB0 - $FFBF
break;
default:
@ -656,22 +656,14 @@ inline uint8_t gime_base_device::read_gime_register(offs_t offset)
uint8_t result;
switch(offset)
{
case 2: // read pending IRQs
case 2: // $FF92 - read pending IRQs
result = m_irq;
if (result != 0x00)
{
m_irq = 0x00;
recalculate_irq();
}
change_gime_irq(0x00);
break;
case 3: // read pending FIRQs
case 3: // $FF93 - read pending FIRQs
result = m_firq;
if (result != 0x00)
{
m_firq = 0x00;
recalculate_firq();
}
change_gime_firq(0x00);
break;
#ifdef NOPE_NOT_READABLE
@ -741,20 +733,20 @@ void gime_base_device::write(offs_t offset, uint8_t data)
switch(offset & 0xF0)
{
case 0x00:
write_gime_register(offset & 0x0F, data);
write_gime_register(offset & 0x0F, data); // $FF90 - $FF9F
break;
case 0x10:
write_mmu_register(offset & 0x0F, data);
write_mmu_register(offset & 0x0F, data); // $FFA0 - $FFAF
break;
case 0x20:
write_palette_register(offset & 0x0F, data & 0x3F);
write_palette_register(offset & 0x0F, data & 0x3F); // $FFB0 - $FFBF
break;
case 0x30:
case 0x40:
write_sam_register(offset - 0x30);
write_sam_register(offset - 0x30); // $FFC0 - $FFDF
break;
}
}
@ -836,6 +828,13 @@ inline void gime_base_device::write_gime_register(offs_t offset, uint8_t data)
(data & 0x02) ? "EI1 " : "",
(data & 0x01) ? "EI0 " : "");
}
// While normally interrupts are acknowledged by reading from this
// register and not writing to it, the act of disabling these interrupts
// has the exact same effect
//
// Kudos to Glen Hewlett for identifying this problem
change_gime_irq(m_irq & data);
break;
case 0x03:
@ -859,6 +858,13 @@ inline void gime_base_device::write_gime_register(offs_t offset, uint8_t data)
(data & 0x02) ? "EI1 " : "",
(data & 0x01) ? "EI0 " : "");
}
// While normally interrupts are acknowledged by reading from this
// register and not writing to it, the act of disabling these interrupts
// has the exact same effect
//
// Kudos to Glen Hewlett for identifying this problem
change_gime_firq(m_firq & data);
break;
case 0x04:
@ -1041,52 +1047,52 @@ inline void gime_base_device::write_sam_register(offs_t offset)
}
//-------------------------------------------------
// interrupt_rising_edge
//-------------------------------------------------
void gime_base_device::interrupt_rising_edge(uint8_t interrupt)
{
/* evaluate IRQ */
// evaluate IRQ
if ((m_gime_registers[0x00] & 0x20) && (m_gime_registers[0x02] & interrupt))
{
m_irq |= interrupt;
recalculate_irq();
}
change_gime_irq(m_irq | interrupt);
/* evaluate FIRQ */
// evaluate FIRQ
if ((m_gime_registers[0x00] & 0x10) && (m_gime_registers[0x03] & interrupt))
change_gime_firq(m_firq | interrupt);
}
//-------------------------------------------------
// change_gime_irq
//-------------------------------------------------
void gime_base_device::change_gime_irq(uint8_t data)
{
// did the value actually change?
if (m_irq != data)
{
m_firq |= interrupt;
recalculate_firq();
m_irq = data;
m_write_irq(irq_r());
}
}
//-------------------------------------------------
// recalculate_irq
// change_gime_firq
//-------------------------------------------------
void gime_base_device::recalculate_irq(void)
void gime_base_device::change_gime_firq(uint8_t data)
{
m_write_irq(irq_r());
// did the value actually change?
if (m_firq != data)
{
m_firq = data;
m_write_firq(firq_r());
}
}
//-------------------------------------------------
// recalculate_firq
//-------------------------------------------------
void gime_base_device::recalculate_firq(void)
{
m_write_firq(firq_r());
}
//**************************************************************************
// VIDEO STATE
//**************************************************************************

8
src/mame/video/gime.h
View File

@ -82,8 +82,8 @@ public:
bool update_rgb(bitmap_rgb32 &bitmap, const rectangle &cliprect);
// interrupt outputs
bool firq_r(void) { return m_firq != 0x00; }
bool irq_r(void) { return m_irq != 0x00; }
bool firq_r() const { return m_firq != 0x00; }
bool irq_r() const { return m_irq != 0x00; }
// interrupt inputs
void set_il0(bool value) { set_interrupt_value(INTERRUPT_EI0, value); }
@ -233,8 +233,8 @@ private:
// interrupts
void interrupt_rising_edge(uint8_t interrupt);
void recalculate_irq(void);
void recalculate_firq(void);
void change_gime_irq(uint8_t data);
void change_gime_firq(uint8_t data);
ATTR_FORCE_INLINE void set_interrupt_value(uint8_t interrupt, bool value)
{