mirror of
https://github.com/ekeeke/Genesis-Plus-GX.git
synced 2024-09-17 11:54:50 +02:00
f3756f260c
.fixed PCM channels loop address (Snatcher) .fixed default TOC for Snatcher .bin image .disabled Mode 1 ROM cartridge write access [Wii/GC] .fixed PCM channels remaining enabled when forcing system hardware
259 lines
7.9 KiB
C
259 lines
7.9 KiB
C
/***************************************************************************************
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* Genesis Plus
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* CD cartridge (external RAM or ROM)
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*
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* Copyright (C) 2012 Eke-Eke (Genesis Plus GX)
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*
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* Redistribution and use of this code or any derivative works are permitted
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* provided that the following conditions are met:
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*
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* - Redistributions may not be sold, nor may they be used in a commercial
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* product or activity.
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*
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* - Redistributions that are modified from the original source must include the
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* complete source code, including the source code for all components used by a
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* binary built from the modified sources. However, as a special exception, the
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* source code distributed need not include anything that is normally distributed
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* (in either source or binary form) with the major components (compiler, kernel,
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* and so on) of the operating system on which the executable runs, unless that
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* component itself accompanies the executable.
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*
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* - Redistributions must reproduce the above copyright notice, this list of
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* conditions and the following disclaimer in the documentation and/or other
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* materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************************/
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#include "shared.h"
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/*--------------------------------------------------------------------------*/
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/* cartridge backup RAM (max. 512KB) */
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/*--------------------------------------------------------------------------*/
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static unsigned int cart_ram_read_byte(unsigned int address)
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{
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/* LSB only */
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if (address & 1)
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{
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return scd.cartridge.area[(address >> 1) & scd.cartridge.mask];
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}
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return 0xff;
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}
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static unsigned int cart_ram_read_word(unsigned int address)
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{
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return (scd.cartridge.area[(address >> 1) & scd.cartridge.mask] | 0xff00);
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}
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static void cart_ram_write_byte(unsigned int address, unsigned int data)
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{
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/* LSB only */
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if (address & 1)
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{
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scd.cartridge.area[(address >> 1) & scd.cartridge.mask] = data;
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}
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}
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static void cart_ram_write_word(unsigned int address, unsigned int data)
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{
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scd.cartridge.area[(address >> 1) & scd.cartridge.mask] = data & 0xff;
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}
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/*--------------------------------------------------------------------------*/
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/* cartridge RAM ID */
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/*--------------------------------------------------------------------------*/
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static unsigned int cart_id_read_byte(unsigned int address)
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{
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/* LSB only */
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if (address & 1)
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{
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return scd.cartridge.id;
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}
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return 0xff;
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}
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static unsigned int cart_id_read_word(unsigned int address)
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{
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return (scd.cartridge.id | 0xff00);
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}
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/*--------------------------------------------------------------------------*/
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/* cartridge RAM write protection */
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/*--------------------------------------------------------------------------*/
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static unsigned int cart_prot_read_byte(unsigned int address)
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{
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/* LSB only */
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if (address & 1)
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{
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return scd.cartridge.prot;
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}
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return 0xff;
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}
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static unsigned int cart_prot_read_word(unsigned int address)
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{
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return (scd.cartridge.prot | 0xff00);
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}
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static void cart_prot_write_byte(unsigned int address, unsigned int data)
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{
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/* LSB only */
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if (address & 1)
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{
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int i;
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if (data & 1)
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{
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/* cartridge is write enabled */
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for (i=0x60; i<0x70; i++)
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{
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m68k.memory_map[i].write8 = cart_ram_write_byte;
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m68k.memory_map[i].write16 = cart_ram_write_word;
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zbank_memory_map[i].write = cart_ram_write_byte;
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}
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}
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else
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{
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/* cartridge is write protected */
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for (i=0x60; i<0x70; i++)
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{
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m68k.memory_map[i].write8 = m68k_unused_8_w;
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m68k.memory_map[i].write16 = m68k_unused_16_w;
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zbank_memory_map[i].write = zbank_unused_w;
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}
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}
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scd.cartridge.prot = data;
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}
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}
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static void cart_prot_write_word(unsigned int address, unsigned int data)
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{
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int i;
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if (data & 1)
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{
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/* cartridge is write enabled */
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for (i=0x60; i<0x70; i++)
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{
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m68k.memory_map[i].write8 = cart_ram_write_byte;
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m68k.memory_map[i].write16 = cart_ram_write_word;
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zbank_memory_map[i].write = cart_ram_write_byte;
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}
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}
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else
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{
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/* cartridge is write protected */
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for (i=0x60; i<0x70; i++)
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{
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m68k.memory_map[i].write8 = m68k_unused_8_w;
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m68k.memory_map[i].write16 = m68k_unused_16_w;
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zbank_memory_map[i].write = zbank_unused_w;
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}
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}
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scd.cartridge.prot = data & 0xff;
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}
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/*--------------------------------------------------------------------------*/
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/* cartridge hardware initialization */
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/*--------------------------------------------------------------------------*/
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void cd_cart_init(void)
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{
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int i;
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/* System boot mode */
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if (scd.cartridge.boot)
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{
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/* disable backup RAM Cart when booting from cartridge (Mode 1) */
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scd.cartridge.id = 0;
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}
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else
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{
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/* enable 512K backup RAM Cart when booting from CD (Mode 2) */
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scd.cartridge.id = 6;
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}
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/* RAM cart enabled ? */
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if (scd.cartridge.id)
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{
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/* cartridge RAM size mask */
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scd.cartridge.mask = (1 << (scd.cartridge.id + 13)) - 1;
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/* enable cartridge RAM write access */
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scd.cartridge.prot = 1;
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/* cartridge ID register (read-only) */
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for (i=0x40; i<0x60; i++)
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{
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m68k.memory_map[i].base = NULL;
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m68k.memory_map[i].read8 = cart_id_read_byte;
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m68k.memory_map[i].read16 = cart_id_read_word;
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m68k.memory_map[i].write8 = m68k_unused_8_w;
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m68k.memory_map[i].write16 = m68k_unused_16_w;
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zbank_memory_map[i].read = cart_id_read_byte;
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zbank_memory_map[i].write = zbank_unused_w;
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}
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/* cartridge RAM */
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for (i=0x60; i<0x70; i++)
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{
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m68k.memory_map[i].base = NULL;
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m68k.memory_map[i].read8 = cart_ram_read_byte;
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m68k.memory_map[i].read16 = cart_ram_read_word;
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m68k.memory_map[i].write8 = cart_ram_write_byte;
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m68k.memory_map[i].write16 = cart_ram_write_word;
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zbank_memory_map[i].read = cart_ram_read_byte;
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zbank_memory_map[i].write = cart_ram_write_byte;
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}
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/* cartridge write protection register */
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for (i=0x70; i<0x80; i++)
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{
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m68k.memory_map[i].base = NULL;
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m68k.memory_map[i].read8 = cart_prot_read_byte;
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m68k.memory_map[i].read16 = cart_prot_read_word;
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m68k.memory_map[i].write8 = cart_prot_write_byte;
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m68k.memory_map[i].write16 = cart_prot_write_word;
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zbank_memory_map[i].read = cart_prot_read_byte;
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zbank_memory_map[i].write = cart_prot_write_byte;
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}
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}
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else
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{
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/* $000000-$3FFFFF (boot from cartridge) or $400000-$7FFFFF (boot from CD) */
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uint8 base = scd.cartridge.boot ^ 0x40;
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/* cartridge ROM */
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for (i=base; i<base+0x40; i++)
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{
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m68k.memory_map[i].base = scd.cartridge.area + ((i & 0x3f) << 16);
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m68k.memory_map[i].read8 = NULL;
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m68k.memory_map[i].read16 = NULL;
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m68k.memory_map[i].write8 = m68k_unused_8_w;
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m68k.memory_map[i].write16 = m68k_unused_16_w;
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zbank_memory_map[i].read = NULL;
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zbank_memory_map[i].write = zbank_unused_w;
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}
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}
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}
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