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Genesis-Plus-GX/source/mem68k.c
ekeeke31 c4c78f58be fixed cart mapper, code cleanup
2008-12-05 16:26:57 +00:00

629 lines
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/***************************************************************************************
* Genesis Plus 1.2a
* 68k memory handlers
*
* Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003 Charles Mac Donald (original code)
* modified by Eke-Eke (compatibility fixes & additional code), GC/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 "m68kcpu.h"
#include "shared.h"
uint32 m68k_read_bus_8(uint32 address)
{
#ifdef LOGERROR
error("Unused read8 %08X (%08X)\n", address, m68k_get_reg (NULL, M68K_REG_PC));
#endif
return m68k_read_pcrelative_8(REG_PC | (address&1));
}
uint32 m68k_read_bus_16(uint32 address)
{
#ifdef LOGERROR
error("Unused read16 %08X (%08X)\n", address, m68k_get_reg (NULL, M68K_REG_PC));
#endif
return m68k_read_pcrelative_16(REG_PC);
}
void m68k_unused_8_w (uint32 address, uint32 data)
{
#ifdef LOGERROR
error("Unused write8 %08X = %02X (%08X)\n", address, data, m68k_get_reg (NULL, M68K_REG_PC));
#endif
}
void m68k_unused_16_w (uint32 address, uint32 data)
{
#ifdef LOGERROR
error("Unused write16 %08X = %04X (%08X)\n", address, data, m68k_get_reg (NULL, M68K_REG_PC));
#endif
}
/*
Functions to handle memory accesses which cause the Genesis to halt
either temporarily (press RESET button to restart) or unrecoverably
(cycle power to restart).
*/
void m68k_lockup_w_8 (uint32 address, uint32 data)
{
#ifdef LOGERROR
error ("Lockup %08X = %02X (%08X)\n", address, data, m68k_get_reg (NULL, M68K_REG_PC));
#endif
gen_running = config.force_dtack;
if (!gen_running) m68k_end_timeslice ();
}
void m68k_lockup_w_16 (uint32 address, uint32 data)
{
#ifdef LOGERROR
error ("Lockup %08X = %04X (%08X)\n", address, data, m68k_get_reg (NULL, M68K_REG_PC));
#endif
gen_running = config.force_dtack;
if (!gen_running) m68k_end_timeslice ();
}
uint32 m68k_lockup_r_8 (uint32 address)
{
#ifdef LOGERROR
error ("Lockup %08X.b (%08X)\n", address, m68k_get_reg (NULL, M68K_REG_PC));
#endif
gen_running = config.force_dtack;
if (!gen_running) m68k_end_timeslice ();
return -1;
}
uint32 m68k_lockup_r_16 (uint32 address)
{
#ifdef LOGERROR
error ("Lockup %08X.w (%08X)\n", address, m68k_get_reg (NULL, M68K_REG_PC));
#endif
gen_running = config.force_dtack;
if (!gen_running) m68k_end_timeslice ();
return -1;
}
/* PICO data */
static int pico_page[7] = {0x00,0x01,0x03,0x07,0x0F,0x1F,0x3F};
/*--------------------------------------------------------------------------*/
/* 68000 memory handlers */
/*--------------------------------------------------------------------------*/
/******* EEPROM **********************************************/
uint32 eeprom_read_byte(uint32 address)
{
if (address == eeprom.type.sda_out_adr) return eeprom_read(address, 0);
else return READ_BYTE(cart_rom, address);
}
uint32 eeprom_read_word(uint32 address)
{
if (address == (eeprom.type.sda_out_adr & 0xfffffe)) return eeprom_read(address, 1);
else return *(uint16 *)(cart_rom + address);
}
void eeprom_write_byte(uint32 address, uint32 data)
{
if ((address == eeprom.type.sda_in_adr) || (address == eeprom.type.scl_adr))
eeprom_write(address, data, 0);
else m68k_unused_8_w(address, data);
}
void eeprom_write_word(uint32 address, uint32 data)
{
if ((address == (eeprom.type.sda_in_adr&0xfffffe)) || (address == (eeprom.type.scl_adr&0xfffffe)))
eeprom_write(address, data, 1);
else m68k_unused_16_w (address, data);
}
/******* Z80 *************************************************/
uint32 z80_read_byte(uint32 address)
{
if (zbusack) return m68k_read_bus_8(address);
switch ((address >> 13) & 3)
{
case 2: /* YM2612 */
return fm_read(0, address & 3);
case 3: /* MISC */
if ((address & 0xff00) == 0x7f00) return m68k_lockup_r_8(address); /* VDP */
else return (m68k_read_bus_8(address) | 0xff);
default: /* ZRAM */
return zram[address & 0x1fff];
}
}
uint32 z80_read_word(uint32 address)
{
if (zbusack) return m68k_read_bus_16(address);
switch ((address >> 13) & 3)
{
case 2: /* YM2612 */
{
int temp = fm_read(0, address & 3);
return (temp << 8 | temp);
}
case 3: /* MISC */
if ((address & 0xff00) == 0x7f00) return m68k_lockup_r_16(address); /* VDP */
else return (m68k_read_bus_16(address) | 0xffff);
default: /* ZRAM */
{
int temp = zram[address & 0x1fff];
return (temp << 8 | temp);
}
}
}
void z80_write_byte(uint32 address, uint32 data)
{
if (zbusack)
{
m68k_unused_8_w(address, data);
return;
}
switch ((address >> 13) & 3)
{
case 2: /* YM2612 */
fm_write(0, address & 3, data);
return;
case 3:
switch ((address >> 8) & 0x7f)
{
case 0x60: /* Bank register */
gen_bank_w(data & 1);
return;
case 0x7f: /* VDP */
m68k_lockup_w_8(address, data);
return;
default:
m68k_unused_8_w(address, data);
return;
}
default: /* ZRAM */
zram[address & 0x1fff] = data;
count_m68k++; /* Z80 bus latency (Pacman 2: New Adventures) */
return;
}
}
void z80_write_word(uint32 address, uint32 data)
{
/* Z80 still hold the bus ? */
if (zbusack)
{
m68k_unused_16_w(address, data);
return;
}
switch ((address >> 13) & 3)
{
case 2: /* YM2612 */
fm_write (0, address & 3, data >> 8);
return;
case 3:
switch ((address >> 8) & 0x7f)
{
case 0x60: /* Bank register */
gen_bank_w ((data >> 8) & 1);
return;
case 0x7f: /* VDP */
m68k_lockup_w_16(address, data);
return;
default:
m68k_unused_16_w(address, data);
return;
}
default: /* ZRAM */
zram[address & 0x1fff] = data >> 8;
return;
}
}
/******* I/O & CTRL ******************************************/
uint32 ctrl_io_read_byte(uint32 address)
{
switch ((address >> 8) & 0xff)
{
case 0x00: /* I/O chip */
if (address & 0xe0) return m68k_read_bus_8(address);
else return (io_read((address >> 1) & 0x0f));
case 0x11: /* BUSACK */
if (address & 1) return m68k_read_bus_8(address);
else return ((m68k_read_pcrelative_8(REG_PC) & 0xfe) | zbusack);
case 0x30: /* TIME */
if (cart_hw.time_r) return cart_hw.time_r(address);
else return m68k_read_bus_8(address);
case 0x10: /* MEMORY MODE */
case 0x12: /* RESET */
case 0x20: /* MEGA-CD */
case 0x40: /* TMSS */
case 0x41: /* BOOTROM */
case 0x44: /* RADICA */
case 0x50: /* SVP REGISTERS */
return m68k_read_bus_8(address);
default: /* Invalid address */
return m68k_lockup_r_8(address);
}
}
uint32 ctrl_io_read_word(uint32 address)
{
switch ((address >> 8) & 0xff)
{
case 0x00: /* I/O chip */
{
if (address & 0xe0) return m68k_read_bus_16(address);
int temp = io_read((address >> 1) & 0x0f);
return (temp << 8 | temp);
}
case 0x11: /* BUSACK */
return ((m68k_read_pcrelative_16(REG_PC) & 0xfeff) | (zbusack << 8));
case 0x30: /* TIME */
if (cart_hw.time_r) return cart_hw.time_r(address);
else return m68k_read_bus_16(address);
case 0x50: /* SVP */
if (svp)
{
if ((address & 0xfd) == 0) return svp->ssp1601.gr[SSP_XST].h;
else if ((address & 0xff) == 4)
{
uint32 temp = svp->ssp1601.gr[SSP_PM0].h;
svp->ssp1601.gr[SSP_PM0].h &= ~1;
return temp;
}
}
return m68k_read_bus_16(address);
case 0x10: /* MEMORY MODE */
case 0x12: /* RESET */
case 0x20: /* MEGA-CD */
case 0x40: /* TMSS */
case 0x41: /* BOOTROM */
case 0x44: /* RADICA */
return m68k_read_bus_16(address);
default: /* Invalid address */
return m68k_lockup_r_16(address);
}
}
void ctrl_io_write_byte(uint32 address, uint32 data)
{
switch ((address >> 8) & 0xff)
{
case 0x00: /* I/O chip */
if ((address & 0xe1) == 0x01) io_write((address >> 1) & 0x0f, data); /* get /LWR only */
else m68k_unused_8_w(address, data);
return;
case 0x11: /* BUSREQ */
if (address & 1) m68k_unused_8_w(address, data);
else gen_busreq_w(data & 1);
return;
case 0x12: /* RESET */
if (address & 1) m68k_unused_8_w(address, data);
else gen_reset_w(data & 1);
return;
case 0x30: /* TIME */
cart_hw.time_w(address, data);
return;
case 0x41: /* BOOTROM */
if (address & 1)
{
m68k_memory_map[0].base = (data & 1) ? default_rom : bios_rom;
/* autodetect BIOS ROM file */
if (!(config.bios_enabled & 2))
{
config.bios_enabled |= 2;
memcpy(bios_rom, cart_rom, 0x800);
memset(cart_rom, 0, genromsize);
}
}
else m68k_unused_8_w (address, data);
return;
case 0x10: /* MEMORY MODE */
case 0x20: /* MEGA-CD */
case 0x40: /* TMSS */
case 0x44: /* RADICA */
case 0x50: /* SVP REGISTERS */
m68k_unused_8_w(address, data);
return;
default: /* Invalid address */
m68k_lockup_w_8(address, data);
return;
}
}
void ctrl_io_write_word(uint32 address, uint32 data)
{
switch ((address >> 8) & 0xff)
{
case 0x00: /* I/O chip */
if (address & 0xe0) m68k_unused_16_w (address, data);
else io_write ((address >> 1) & 0x0f, data & 0xff);
return;
case 0x11: /* BUSREQ */
gen_busreq_w ((data >> 8) & 1);
return;
case 0x12: /* RESET */
gen_reset_w ((data >> 8) & 1);
return;
case 0x50: /* SVP REGISTERS */
if (svp)
{
if (address & 0xfd) m68k_unused_16_w(address, data);
else
{
/* just guessing here (Notaz) */
svp->ssp1601.gr[SSP_XST].h = data;
svp->ssp1601.gr[SSP_PM0].h |= 2;
svp->ssp1601.emu_status &= ~SSP_WAIT_PM0;
}
}
else m68k_unused_16_w (address, data);
return;
case 0x30: /* TIME */
cart_hw.time_w(address & 0xfe, data >> 8);
cart_hw.time_w(address, data & 0xff);
return;
case 0x41: /* BOOTROM */
m68k_memory_map[0].base = (data & 1) ? default_rom : bios_rom;
/* autodetect BIOS ROM file */
if (!(config.bios_enabled & 2))
{
config.bios_enabled |= 2;
memcpy(bios_rom, cart_rom, 0x800);
memset(cart_rom, 0, genromsize);
}
return;
case 0x10: /* MEMORY MODE */
case 0x20: /* MEGA-CD */
case 0x40: /* TMSS */
case 0x44: /* RADICA */
m68k_unused_16_w (address, data);
return;
default: /* Unused */
m68k_lockup_w_16 (address, data);
return;
}
}
/******* VDP *************************************************/
uint32 vdp_read_byte(uint32 address)
{
switch (address & 0xfd)
{
case 0x00: /* DATA */
return (vdp_data_r() >> 8);
case 0x01: /* DATA */
return (vdp_data_r() & 0xff);
case 0x04: /* CTRL */
return ((m68k_read_pcrelative_8(REG_PC) & 0xfc) | ((vdp_ctrl_r() >> 8) & 3));
case 0x05: /* CTRL */
return (vdp_ctrl_r() & 0xff);
case 0x08: /* HVC */
case 0x0c:
return (vdp_hvc_r() >> 8);
case 0x09: /* HVC */
case 0x0d:
return (vdp_hvc_r() & 0xff);
case 0x18: /* Unused */
case 0x19:
case 0x1c:
case 0x1d:
return m68k_read_bus_8(address);
default: /* Invalid address */
return m68k_lockup_r_8(address);
}
}
uint32 vdp_read_word(uint32 address)
{
switch (address & 0xfc)
{
case 0x00: /* DATA */
return vdp_data_r();
case 0x04: /* CTRL */
return ((vdp_ctrl_r() & 0x3FF) | (m68k_read_pcrelative_16(REG_PC) & 0xFC00));
case 0x08: /* HVC */
case 0x0c:
return vdp_hvc_r();
case 0x18: /* Unused */
case 0x1c:
return m68k_read_bus_16(address);
default: /* Invalid address */
return m68k_lockup_r_16(address);
}
}
void vdp_write_byte(uint32 address, uint32 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(0, data);
else m68k_unused_8_w(address, data);
return;
case 0x18: /* Unused */
m68k_unused_8_w(address, data);
return;
case 0x1c: /* TEST register */
vdp_test_w(data << 8 | data);
return;
default: /* Invalid address */
m68k_lockup_w_8(address, data);
return;
}
}
void vdp_write_word(uint32 address, uint32 data)
{
switch (address & 0xfc)
{
case 0x00: /* DATA */
vdp_data_w(data);
return;
case 0x04: /* CTRL */
vdp_ctrl_w(data);
return;
case 0x10: /* PSG */
case 0x14:
psg_write(0, data & 0xff);
return;
case 0x18: /* Unused */
m68k_unused_16_w(address, data);
return;
case 0x1c: /* Test register */
vdp_test_w(data);
return;
default: /* Invalid address */
m68k_lockup_w_16 (address, data);
return;
}
}
/******* PICO ************************************************/
uint32 pico_read_byte(uint32 address)
{
/* PICO */
switch (address & 0xff)
{
case 0x01: /* VERSION register */
return (0x40);
case 0x03: /* IO register */
{
uint8 retval = 0xff;
if (input.pad[0] & INPUT_B) retval &= ~0x10;
if (input.pad[0] & INPUT_A) retval &= ~0x80;
if (input.pad[0] & INPUT_UP) retval &= ~0x01;
if (input.pad[0] & INPUT_DOWN) retval &= ~0x02;
if (input.pad[0] & INPUT_LEFT) retval &= ~0x04;
if (input.pad[0] & INPUT_RIGHT) retval &= ~0x08;
retval &= ~0x20;
retval &= ~0x40;
return retval;
}
case 0x05: /* MSB PEN X coordinate */
return (input.analog[0][0] >> 8);
case 0x07: /* LSB PEN X coordinate */
return (input.analog[0][0] & 0xff);
case 0x09: /* MSB PEN Y coordinate */
return (input.analog[0][1] >> 8);
case 0x0b: /* LSB PEN Y coordinate */
return (input.analog[0][1] & 0xff);
case 0x0d: /* PAGE register */
return pico_page[pico_current]; /* TODO */
case 0x10: /* PCM registers */
case 0x11:
case 0x12:
case 0x13:
return 0x80; /* TODO */
default:
return m68k_read_bus_8(address);
}
}
uint32 pico_read_word(uint32 address)
{
return ((m68k_read_bus_8(address) << 8) | pico_read_byte(address | 1));
}
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