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XaviX - IRQ source register notes (#3302)

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* XaviX - new machines marked as NOT WORKING
Let's! TV Play Classic - Taito Nostalgia 2 [Sean Riddle, Mr. Do]

(boots to the title screen before going off the rails)

* xavix - some notes about the irq source register based on code analysis (nw)
This commit is contained in:
David Haywood 2018-03-06 01:32:21 +00:00 committed by R. Belmont
parent 4f52df727a
commit 4431d2e723
1 changed files with 51 additions and 15 deletions
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66
src/mame/drivers/xavix.cpp
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@ -126,6 +126,9 @@ public:
DECLARE_WRITE8_MEMBER(irq_vector1_lo_w);
DECLARE_WRITE8_MEMBER(irq_vector1_hi_w);
DECLARE_READ8_MEMBER(irq_source_r);
DECLARE_WRITE8_MEMBER(irq_source_w);
DECLARE_READ8_MEMBER(xavix_6ff0_r);
DECLARE_WRITE8_MEMBER(xavix_6ff0_w);
@ -822,21 +825,28 @@ uint32_t xavix_state::screen_update(screen_device &screen, bitmap_ind16 &bitmap,
WRITE8_MEMBER(xavix_state::dma_trigger_w)
{
logerror("%s: dma_trigger_w %02x\n", machine().describe_context(), data);
uint32_t source = (m_rom_dmasrc_hi_data << 16) | (m_rom_dmasrc_md_data<<8) | m_rom_dmasrc_lo_data;
uint16_t dest = (m_rom_dmadst_hi_data<<8) | m_rom_dmadst_lo_data;
uint16_t len = (m_rom_dmalen_hi_data<<8) | m_rom_dmalen_lo_data;
source &= m_rgnlen-1;
logerror(" (possible DMA op SRC %08x DST %04x LEN %04x)\n", source, dest, len);
address_space& destspace = m_maincpu->space(AS_PROGRAM);
for (int i = 0; i < len; i++)
if (data == 0x01)
{
uint8_t dat = m_rgn[(source + i) & (m_rgnlen-1)];
destspace.write_byte(dest + i, dat);
logerror("%s: dma_trigger_w (do DMA?)\n", machine().describe_context());
uint32_t source = (m_rom_dmasrc_hi_data << 16) | (m_rom_dmasrc_md_data << 8) | m_rom_dmasrc_lo_data;
uint16_t dest = (m_rom_dmadst_hi_data << 8) | m_rom_dmadst_lo_data;
uint16_t len = (m_rom_dmalen_hi_data << 8) | m_rom_dmalen_lo_data;
source &= m_rgnlen - 1;
logerror(" (possible DMA op SRC %08x DST %04x LEN %04x)\n", source, dest, len);
address_space& destspace = m_maincpu->space(AS_PROGRAM);
for (int i = 0; i < len; i++)
{
uint8_t dat = m_rgn[(source + i) & (m_rgnlen - 1)];
destspace.write_byte(dest + i, dat);
}
}
else // the interrupt routine writes 0x80 to the trigger, maybe 'clear IRQ?'
{
logerror("%s: dma_trigger_w (unknown) %02x\n", machine().describe_context(), data);
}
}
@ -1351,6 +1361,29 @@ READ8_MEMBER(xavix_state::xavix_4000_r)
}
}
READ8_MEMBER(xavix_state::irq_source_r)
{
/* the 2nd IRQ routine (regular IRQ, not NMI?) reads here before deciding what to do
the following bits have been seen to be checked (active low?)
0x40 - Monster Truck - stuff with 6ffb 6fd6 and 6ff8
0x20 - most games (but not Monster Truck) - DMA related?
0x10 - card night + monster truck - 7c00 related? (increases 16-bit counter in ram stores 0xc1 at 7c00)
0x08 - several games - Input related (ADC? - used for analog control on Monster Truck) (uses 7a80 top bit to determine direction, and 7a81 0x08 as an output, presumably to clock)
0x04 - Monster Truck - loads/stores 7b81
*/
logerror("%s: irq_source_r\n", machine().describe_context());
return 0xff;
}
WRITE8_MEMBER(xavix_state::irq_source_w)
{
logerror("%s: irq_source_w %02x\n", machine().describe_context(), data);
// cleared on startup in monster truck, no purpose?
}
// DATA reads from 0x8000-0xffff are banked by byte 0xff of 'ram' (this is handled in the CPU core)
ADDRESS_MAP_START(xavix_state::xavix_map)
@ -1461,10 +1494,13 @@ ADDRESS_MAP_START(xavix_state::xavix_map)
AM_RANGE(0x007ff5, 0x007ff6) AM_READ(mult_r)
// maybe irq enable, written after below
AM_RANGE(0x007ff9, 0x007ff9) AM_WRITE(irq_enable_w)
AM_RANGE(0x007ff9, 0x007ff9) AM_WRITE(irq_enable_w) // interrupt related, but probalby not a simple 'enable' otherwise interrupts happen before we're ready for them.
// an IRQ vector (nmi?)
AM_RANGE(0x007ffa, 0x007ffa) AM_WRITE(irq_vector0_lo_w)
AM_RANGE(0x007ffb, 0x007ffb) AM_WRITE(irq_vector0_hi_w)
AM_RANGE(0x007ffc, 0x007ffc) AM_READWRITE(irq_source_r, irq_source_w)
// an IRQ vector (irq?)
AM_RANGE(0x007ffe, 0x007ffe) AM_WRITE(irq_vector1_lo_w)
AM_RANGE(0x007fff, 0x007fff) AM_WRITE(irq_vector1_hi_w)