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[COCO3] Mapped several IO reads to the floating bus (bug #05135)

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This commit is contained in:
Nathan Woods 2013-02-03 12:33:34 +00:00
parent cef19d5cfe
commit d5a25f279d
1 changed files with 13 additions and 10 deletions
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23
src/mess/video/gime.c
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@ -661,6 +661,10 @@ UINT8 gime_base_device::read(offs_t offset)
case 0x20:
data = read_palette_register(offset);
break;
default:
data = read_floating_bus();
break;
}
return data;
@ -679,7 +683,7 @@ ATTR_FORCE_INLINE UINT8 gime_base_device::read_gime_register(offs_t offset)
UINT8 result;
switch(offset)
{
case 2: /* Read pending IRQs */
case 2: // read pending IRQs
result = m_irq;
if (result != 0x00)
{
@ -688,7 +692,7 @@ ATTR_FORCE_INLINE UINT8 gime_base_device::read_gime_register(offs_t offset)
}
break;
case 3: /* Read pending FIRQs */
case 3: // read pending FIRQs
result = m_firq;
if (result != 0x00)
{
@ -697,16 +701,15 @@ ATTR_FORCE_INLINE UINT8 gime_base_device::read_gime_register(offs_t offset)
}
break;
case 4: /* Timer MSB/LSB; these arn't readable */
case 5:
/* JK tells me that these values are indeterminate; and $7E appears
* to be the value most commonly returned
*/
result = 0x7E;
case 14:
case 15:
// these (I guess) are readable (Mametesters bug #05135)
result = m_gime_registers[offset];
break;
default:
result = m_gime_registers[offset];
// the others are not readable; read floating bus (Mametesters bug #05135)
result = read_floating_bus();
break;
}
return result;
@ -720,7 +723,7 @@ ATTR_FORCE_INLINE UINT8 gime_base_device::read_gime_register(offs_t offset)
ATTR_FORCE_INLINE UINT8 gime_base_device::read_mmu_register(offs_t offset)
{
return (m_mmu[offset & 0x0F] & 0x3F);
return (m_mmu[offset & 0x0F] & 0x3F) | (read_floating_bus() & 0xC0);
}