The-Homebrew-Cloud/Genesis-Plus-GX
2
0
Fork 0
mirror of https://github.com/ekeeke/Genesis-Plus-GX.git synced 2024-12-28 12:11:50 +01:00
Code Issues Packages Projects Releases Wiki Activity

More changes to Z80 bus request/reset

Browse Source
This commit is contained in:
ekeeke31 2010-06-18 11:02:10 +00:00
parent 84a395dbf3
commit fb4663f2e3
1 changed files with 62 additions and 52 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

110
source/genesis.c
View File

@ -138,15 +138,15 @@ void gen_hardreset(void)
m68k_memory_map[0].base = bios_rom;
}
/* Reset CPU cycles (check EA logo corruption, no glitches for Skitchin/Budokan on PAL 60hz MD2 with TMSS) */
mcycles_68k = mcycles_z80 = (rand() % lines_per_frame) * MCYCLES_PER_LINE;
/* Reset CPU cycles */
mcycles_68k = mcycles_z80 = 0;
/* Z80 bus is released & Z80 reset is asserted */
zstate = 0;
/* Z80 bus is released & Z80 is stopped */
m68k_memory_map[0xa0].read8 = m68k_read_bus_8;
m68k_memory_map[0xa0].read16 = m68k_read_bus_16;
m68k_memory_map[0xa0].write8 = m68k_unused_8_w;
m68k_memory_map[0xa0].write16 = m68k_unused_16_w;
zstate = 0;
/* Assume default bank is $000000-$007FFF */
zbank = 0;
@ -256,20 +256,16 @@ unsigned int gen_bankswitch_r(void)
/*-----------------------------------------------------------------------
Z80 Bus controller chip functions
-----------------------------------------------------------------------*/
void gen_zbusreq_w(unsigned int state, unsigned int cycles)
void gen_zbusreq_w(unsigned int data, unsigned int cycles)
{
if (state) /* !ZBUSREQ asserted */
if (data) /* !ZBUSREQ asserted */
{
/* if z80 was running, resynchronize with 68k */
/* check if Z80 is going to be stopped */
if (zstate == 1)
{
/* resynchronize with 68k */
z80_run(cycles);
/* update Z80 bus status */
zstate |= 2;
/* check if Z80 reset is released */
if (zstate & 1)
{
/* enable 68k access to Z80 bus */
_m68k_memory_map *base = &m68k_memory_map[0xa0];
base->read8 = z80_read_byte;
@ -277,65 +273,73 @@ void gen_zbusreq_w(unsigned int state, unsigned int cycles)
base->write8 = z80_write_byte;
base->write16 = z80_write_word;
}
/* update Z80 bus status */
zstate |= 2;
}
else /* !ZBUSREQ released */
{
/* if z80 is restarted, resynchronize with 68k */
/* check if Z80 is going to be restarted */
if (zstate == 3)
{
/* resynchronize with 68k */
mcycles_z80 = cycles;
/* update Z80 bus status */
zstate &= 1;
/* disable 68k access */
/* disable 68k access to Z80 bus */
_m68k_memory_map *base = &m68k_memory_map[0xa0];
base->read8 = m68k_read_bus_8;
base->read16 = m68k_read_bus_16;
base->write8 = m68k_unused_8_w;
base->write16 = m68k_unused_16_w;
}
}
void gen_zreset_w(unsigned int state, unsigned int cycles)
{
/* detect !ZRESET transitions */
if (state == (zstate & 1))
return;
if (state) /* !ZRESET released */
{
/* if z80 is restarted, resynchronize with 68k */
if (!zstate)
mcycles_z80 = cycles;
/* update Z80 bus status */
zstate |= 1;
zstate &= 1;
}
}
/* check if Z80 bus has been requested */
if (zstate & 2)
void gen_zreset_w(unsigned int data, unsigned int cycles)
{
/* enable 68k access to Z80 bus */
_m68k_memory_map *base = &m68k_memory_map[0xa0];
base->read8 = z80_read_byte;
base->read16 = z80_read_word;
base->write8 = z80_write_byte;
base->write16 = z80_write_word;
}
}
else /* !ZRESET asserted */
if (data) /* !ZRESET released */
{
/* if z80 was running, resynchronize with 68k */
if (zstate == 1)
z80_run(cycles);
/* check if Z80 is going to be restarted */
if (zstate == 0)
{
/* resynchronize with 68k */
mcycles_z80 = cycles;
/* reset Z80 & YM2612 */
z80_reset();
fm_reset(cycles);
}
/* check if 68k access to Z80 bus is granted */
else if (zstate == 2)
{
/* enable 68k access to Z80 bus */
_m68k_memory_map *base = &m68k_memory_map[0xa0];
base->read8 = z80_read_byte;
base->read16 = z80_read_word;
base->write8 = z80_write_byte;
base->write16 = z80_write_word;
}
/* update Z80 bus status */
zstate &= 2;
zstate |= 1;
}
else /* !ZRESET asserted */
{
/* check if Z80 is going to be stopped */
if (zstate == 1)
{
/* resynchronize with 68k */
z80_run(cycles);
}
/* disable 68k access */
/* check if 68k had access to Z80 bus */
else if (zstate == 3)
{
/* disable 68k access to Z80 bus */
_m68k_memory_map *base = &m68k_memory_map[0xa0];
base->read8 = m68k_read_bus_8;
base->read16 = m68k_read_bus_16;
@ -343,11 +347,17 @@ void gen_zreset_w(unsigned int state, unsigned int cycles)
base->write16 = m68k_unused_16_w;
}
/* stop YM2612 */
fm_reset(cycles);
/* update Z80 bus status */
zstate &= 2;
}
}
void gen_zbank_w (unsigned int state)
void gen_zbank_w (unsigned int data)
{
zbank = ((zbank >> 1) | ((state & 1) << 23)) & 0xFF8000;
zbank = ((zbank >> 1) | ((data & 1) << 23)) & 0xFF8000;
}
int z80_irq_callback (int param)