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Haze: Cleaned up DMA function when SVP is used (Virtua Racing Genesis), avoiding duplicate code. (no whatsnew)

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Scott Stone 2010-09-29 03:25:16 +00:00
parent 1fb365862c
commit 89e7e7e881
1 changed files with 5 additions and 29 deletions
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34
src/mame/drivers/megadriv.c
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@ -622,12 +622,16 @@ static UINT16 vdp_get_word_from_68k_mem_default(running_machine *machine, UINT32
{
// should we limit the valid areas here?
// how does this behave with the segacd etc?
// svp uses it's own function elsewhere...
// note, the RV bit on 32x is important for this to work, because it causes a normal cart mapping - see tempo
address_space *space68k = machine->device<legacy_cpu_device>("maincpu")->space();
if (( source >= 0x000000 ) && ( source <= 0x3fffff ))
{
if (_svp_cpu != NULL)
{
source -= 2; // the SVP introduces some kind of DMA 'lag', which we have to compensate for, this is obvious even on gfx DMAd from ROM (the Speedometer)
}
return space68k->read_word(source);
}
else if (( source >= 0xe00000 ) && ( source <= 0xffffff ))
@ -3893,33 +3897,6 @@ static ADDRESS_MAP_START( svp_ext_map, ADDRESS_SPACE_IO, 16 )
ADDRESS_MAP_END
/* DMA read function for SVP */
static UINT16 vdp_get_word_from_68k_mem_svp(running_machine *machine, UINT32 source)
{
if ((source & 0xe00000) == 0x000000)
{
UINT16 *rom = (UINT16*)memory_region(machine, "maincpu");
source -= 2; // DMA latency
return rom[source >> 1];
}
else if ((source & 0xfe0000) == 0x300000)
{
UINT16 *dram = (UINT16*)svp.dram;
source &= 0x1fffe;
source -= 2;
return dram[source >> 1];
}
else if ((source & 0xe00000) == 0xe00000)
{
return megadrive_ram[(source&0xffff)>>1];
}
else
{
mame_printf_debug("DMA Read unmapped %06x\n",source);
return mame_rand(machine);
}
}
/* emulate testmode plug */
static UINT8 megadrive_io_read_data_port_svp(running_machine *machine, int portnum)
{
@ -3960,7 +3937,6 @@ static void svp_init(running_machine *machine)
ROM = memory_region(machine, "maincpu");
memory_set_bankptr(machine, "bank4", ROM + 0x800 );
vdp_get_word_from_68k_mem = vdp_get_word_from_68k_mem_svp;
megadrive_io_read_data_port_ptr = megadrive_io_read_data_port_svp;
}