Genesis-Plus-GX/source/membnk.c
ekeeke31 3434f89e3b .fixed optimization of memory handlers (better branch prediction ?)
.fixed savestate snaphot when 16:9 correction is used
.fixed overscan support (separated H & V border emulation)
2010-06-15 06:14:35 +00:00

306 lines
6.4 KiB
C

/***************************************************************************************
* Genesis Plus
* Z80 bank access to 68k bus
*
* Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003 Charles Mac Donald (original code)
* Eke-Eke (2007,2008,2009), additional code & fixes for the GCN/Wii port
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
****************************************************************************************/
#include "shared.h"
/*
Handlers for access to unused addresses and those which make the
machine lock up.
*/
unsigned int zbank_unused_r(unsigned int address)
{
#ifdef LOGERROR
error("Z80 bank unused read %06X\n", address);
#endif
return (address & 1) ? 0x00 : 0xff;
}
void zbank_unused_w(unsigned int address, unsigned int data)
{
#ifdef LOGERROR
error("Z80 bank unused write %06X = %02X\n", address, data);
#endif
}
unsigned int zbank_lockup_r(unsigned int address)
{
#ifdef LOGERROR
error("Z80 bank lockup read %06X\n", address);
#endif
if (!config.force_dtack)
{
mcycles_z80 = 0xffffffff;
zstate = 0;
}
return 0xff;
}
void zbank_lockup_w(unsigned int address, unsigned int data)
{
#ifdef LOGERROR
error("Z80 bank lockup write %06X = %02X\n", address, data);
#endif
if (!config.force_dtack)
{
mcycles_z80 = 0xffffffff;
zstate = 0;
}
}
/* I/O & Control registers */
unsigned int zbank_read_ctrl_io(unsigned int address)
{
switch ((address >> 8) & 0xff)
{
case 0x00: /* I/O chip */
{
if (!(address & 0xe0))
{
return (io_read((address >> 1) & 0x0f));
}
return zbank_unused_r(address);
}
case 0x11: /* BUSACK */
{
if (address & 1)
{
return zbank_unused_r(address);
}
return 0xff;
}
case 0x30: /* TIME */
{
if (cart.hw.time_r)
{
unsigned int data = cart.hw.time_r(address);
if (address & 1)
{
return (data & 0xff);
}
return (data >> 8);
}
return zbank_unused_r(address);
}
case 0x41: /* OS ROM */
{
if (address & 1)
{
return (gen_bankswitch_r() | 0xfe);
}
return zbank_unused_r(address);
}
case 0x10: /* MEMORY MODE */
case 0x12: /* RESET */
case 0x20: /* MEGA-CD */
case 0x40: /* TMSS */
case 0x44: /* RADICA */
case 0x50: /* SVP REGISTERS */
{
return zbank_unused_r(address);
}
default: /* Invalid address */
{
return zbank_lockup_r(address);
}
}
}
void zbank_write_ctrl_io(unsigned int address, unsigned int data)
{
switch ((address >> 8) & 0xff)
{
case 0x00: /* I/O chip */
{
/* get /LWR only */
if ((address & 0xe1) == 0x01)
{
io_write((address >> 1) & 0x0f, data);
return;
}
zbank_unused_w(address, data);
return;
}
case 0x11: /* BUSREQ */
{
if (!(address & 1))
{
gen_zbusreq_w(data & 1, mcycles_z80);
return;
}
zbank_unused_w(address, data);
return;
}
case 0x12: /* RESET */
{
if (!(address & 1))
{
gen_zreset_w(data & 1, mcycles_z80);
return;
}
zbank_unused_w(address, data);
return;
}
case 0x30: /* TIME */
{
cart.hw.time_w(address, data);
return;
}
case 0x41: /* OS ROM */
{
if (address & 1)
{
gen_bankswitch_w(data & 1);
return;
}
zbank_unused_w(address, data);
return;
}
case 0x10: /* MEMORY MODE */
case 0x20: /* MEGA-CD */
case 0x40: /* TMSS */
case 0x44: /* RADICA */
case 0x50: /* SVP REGISTERS */
{
zbank_unused_w(address, data);
return;
}
default: /* Invalid address */
{
zbank_lockup_w(address, data);
return;
}
}
}
/* VDP */
unsigned int zbank_read_vdp(unsigned int address)
{
switch (address & 0xfd)
{
case 0x00: /* DATA */
{
return (vdp_data_r() >> 8);
}
case 0x01: /* DATA */
{
return (vdp_data_r() & 0xff);
}
case 0x04: /* CTRL */
{
return (((vdp_ctrl_r(mcycles_z80) >> 8) & 3) | 0xfc);
}
case 0x05: /* CTRL */
{
return (vdp_ctrl_r(mcycles_z80) & 0xff);
}
case 0x08: /* HVC */
case 0x0c:
{
return (vdp_hvc_r(mcycles_z80) >> 8);
}
case 0x09: /* HVC */
case 0x0d:
{
return (vdp_hvc_r(mcycles_z80) & 0xff);
}
case 0x18: /* Unused */
case 0x19:
case 0x1c:
case 0x1d:
{
return zbank_unused_r(address);
}
default: /* Invalid address */
{
return zbank_lockup_r(address);
}
}
}
void zbank_write_vdp(unsigned int address, unsigned int data)
{
switch (address & 0xfc)
{
case 0x00: /* Data port */
{
vdp_data_w(data << 8 | data);
return;
}
case 0x04: /* Control port */
{
vdp_ctrl_w(data << 8 | data);
return;
}
case 0x10: /* PSG */
case 0x14:
{
if (address & 1)
{
psg_write(mcycles_z80, data);
return;
}
zbank_unused_w(address, data);
return;
}
case 0x18: /* Unused */
{
zbank_unused_w(address, data);
return;
}
case 0x1c: /* TEST register */
{
vdp_test_w(data << 8 | data);
return;
}
default: /* Invalid address */
{
zbank_lockup_w(address, data);
return;
}
}
}