117 lines
3.0 KiB
C
117 lines
3.0 KiB
C
#include <bus.h>
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#include <common.h>
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#include <cart.h>
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#include <cpu.h>
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#include <ram.h>
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#include <io.h>
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// 0x0000 - 0x3FFF : ROM Bank 0
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// 0x4000 - 0x7FFF : ROM Bank 1 - Switchable
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// 0x8000 - 0x97FF : CHR RAM
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// 0x9800 - 0x9BFF : BG Map 1
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// 0x9C00 - 0x9FFF : BG Map 2
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// 0xA000 - 0xBFFF : Cartridge RAM
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// 0xC000 - 0xCFFF : RAM Bank 0
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// 0xD000 - 0xDFFF : RAM Bank 1-7 - switchable - Color only
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// 0xE000 - 0xFDFF : Reserved - Echo RAM
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// 0xFE00 - 0xFE9F : Object Attribute Memory
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// 0xFEA0 - 0xFEFF : Reserved - Unusable
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// 0xFF00 - 0xFF7F : I/O Registers
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// 0xFF80 - 0xFFFE : Zero Page
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u8 bus_read(u16 address) {
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if(address < 0x8000) {
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return cart_read(address);
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} else if (address < 0xA000) {
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//Char/Map Data
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//TODO
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printf("UNSUPPORTED bus_read(%04X)\n", address);
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//NO_IMPL
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return 0;
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} else if (address < 0xC000) {
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//Cartridge RAM
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return cart_read(address);
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} else if (address < 0xE000) {
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//WRAM (Working RAM)
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return wram_read(address);
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} else if (address < 0xFE00) {
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//reserved echo ram...
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return 0;
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} else if (address < 0xFEA0) {
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//OAM
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//TODO
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printf("UNSUPPORTED bus_read(%04X)\n", address);
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//NO_IMPL
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return 0;
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} else if (address < 0xFF00) {
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//reserved unusable
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return 0;
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} else if (address < 0xFF80) {
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//IO registers
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//TODO
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//NO_IMPL
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return io_read(address);
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} else if (address == 0xFFFF) {
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//CPU ENABLE REGISTER
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//TODO
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return cpu_get_ie_register();
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}
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return hram_read(address);
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}
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void bus_write(u16 address, u8 value) {
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if(address < 0x8000) {
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cart_write(address, value);
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return;
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} else if (address < 0xA000) {
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//Char/Map Data
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//TODO
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printf("UNSUPPORTED bus_write(%04X)\n", address);
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return;
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//NO_IMPL
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} else if (address < 0xC000) {
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//Cartridge RAM
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cart_write(address, value);
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return;
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} else if (address < 0xE000) {
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//WRAM (Working RAM)
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wram_write(address, value);
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return;
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} else if (address < 0xFE00) {
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//reserved echo ram...
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return;
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} else if (address < 0xFEA0) {
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//OAM
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//TODO
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printf("UNSUPPORTED bus_write(%04X)\n", address);
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return;
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//NO_IMPL
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} else if (address < 0xFF00) {
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//reserved unusable
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return;
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} else if (address < 0xFF80) {
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//IO registers
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//TODO
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io_write(address, value);
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//NO_IMPL
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return;
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} else if (address == 0xFFFF) {
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//CPU ENABLE REGISTER
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cpu_set_ie_register(value);
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return;
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}
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hram_write(address, value);
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}
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u16 bus_read16(u16 address) {
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u16 lo = bus_read(address);
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u16 hi = bus_read(address+1);
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return lo | (hi << 8);
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}
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void bus_write16(u16 address, u16 value) {
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bus_write(address+1, (value >> 8) & 0xFF);
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bus_write(address, value & 0xFF);
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} |