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bsnes/Core/memory.c

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#include <stdio.h>
#include <stdbool.h>
#include "gb.h"
#include "joypad.h"
#include "display.h"
#include "memory.h"
typedef unsigned char GB_read_function_t(GB_gameboy_t *gb, unsigned short addr);
typedef void GB_write_function_t(GB_gameboy_t *gb, unsigned short addr, unsigned char value);
static unsigned char read_rom(GB_gameboy_t *gb, unsigned short addr)
{
if (addr < 0x100 && !gb->bios_finished) {
return gb->bios[addr];
}
if (addr >= 0x200 && addr < 0x900 && gb->is_cgb && !gb->bios_finished) {
return gb->bios[addr];
}
if (!gb->rom_size) {
return 0xFF;
}
return gb->rom[addr];
}
static unsigned char read_mbc_rom(GB_gameboy_t *gb, unsigned short addr)
{
if (gb->mbc_rom_bank >= gb->rom_size / 0x4000) {
return 0xFF;
}
return gb->rom[(addr & 0x3FFF) + gb->mbc_rom_bank * 0x4000];
}
static unsigned char read_vram(GB_gameboy_t *gb, unsigned short addr)
{
if ((gb->io_registers[GB_IO_STAT] & 0x3) == 3) {
return 0xFF;
}
return gb->vram[(addr & 0x1FFF) + (unsigned short) gb->cgb_vram_bank * 0x2000];
}
static unsigned char read_mbc_ram(GB_gameboy_t *gb, unsigned short addr)
{
if (gb->cartridge_type->has_rtc && gb->mbc_ram_bank >= 8 && gb->mbc_ram_bank <= 0xC) {
/* RTC read */
gb->rtc_high |= ~0xC1; /* Not all bytes in RTC high are used. */
return gb->rtc_data[gb->mbc_ram_bank - 8];
}
unsigned int ram_index = (addr & 0x1FFF) + gb->mbc_ram_bank * 0x2000;
if (!gb->mbc_ram_enable)
{
gb_log(gb, "Read from %02x:%04x (%06x) (Disabled MBC RAM)\n", gb->mbc_ram_bank, addr, ram_index);
return 0xFF;
}
if (ram_index >= gb->mbc_ram_size) {
gb_log(gb, "Read from %02x:%04x (%06x) (Unmapped MBC RAM)\n", gb->mbc_ram_bank, addr, ram_index);
return 0xFF;
}
return gb->mbc_ram[(addr & 0x1FFF) + gb->mbc_ram_bank * 0x2000];
}
static unsigned char read_ram(GB_gameboy_t *gb, unsigned short addr)
{
return gb->ram[addr & 0x0FFF];
}
static unsigned char read_banked_ram(GB_gameboy_t *gb, unsigned short addr)
{
return gb->ram[(addr & 0x0FFF) + gb->cgb_ram_bank * 0x1000];
}
static unsigned char read_high_memory(GB_gameboy_t *gb, unsigned short addr)
{
if (addr < 0xFE00) {
return gb->ram[addr & 0x0FFF];
}
if (addr < 0xFEA0) {
if ((gb->io_registers[GB_IO_STAT] & 0x3) >= 2) {
return 0xFF;
}
return gb->oam[addr & 0xFF];
}
if (addr < 0xFF00) {
/* Unusable, simulate Gameboy Color */
if ((gb->io_registers[GB_IO_STAT] & 0x3) >= 2) { /* Seems to be disabled in Modes 2 and 3 */
return 0xFF;
}
return (addr & 0xF0) | ((addr >> 4) & 0xF);
}
if (addr < 0xFF80) {
switch (addr & 0xFF) {
case GB_IO_IF:
return gb->io_registers[GB_IO_IF] | 0xE0;
case GB_IO_TAC:
return gb->io_registers[GB_IO_TAC] | 0xF8;
case GB_IO_STAT:
return gb->io_registers[GB_IO_STAT] | 0x80;
case GB_IO_DMG_EMULATION_INDICATION:
return gb->io_registers[GB_IO_DMG_EMULATION_INDICATION] | 0xFE;
case GB_IO_JOYP:
case GB_IO_DIV:
case GB_IO_TIMA:
case GB_IO_TMA:
case GB_IO_LCDC:
case GB_IO_SCY:
case GB_IO_SCX:
case GB_IO_LY:
case GB_IO_LYC:
case GB_IO_BGP:
case GB_IO_OBP0:
case GB_IO_OBP1:
case GB_IO_WY:
case GB_IO_WX:
case GB_IO_HDMA1:
case GB_IO_HDMA2:
case GB_IO_HDMA3:
case GB_IO_HDMA4:
case GB_IO_PCM_12:
case GB_IO_PCM_34:
case GB_IO_SB:
return gb->io_registers[addr & 0xFF];
case GB_IO_HDMA5:
return gb->io_registers[GB_IO_HDMA5] | 0x7F;
case GB_IO_SVBK:
if (!gb->cgb_mode) {
return 0xFF;
}
return gb->cgb_ram_bank | ~0x7;
case GB_IO_VBK:
if (!gb->cgb_mode) {
return 0xFF;
}
return gb->cgb_vram_bank | ~0x1;
case GB_IO_BGPI:
case GB_IO_OBPI:
if (!gb->is_cgb) {
return 0xFF;
}
return gb->io_registers[addr & 0xFF] | 0x40;
case GB_IO_BGPD:
case GB_IO_OBPD:
{
if (!gb->is_cgb) {
return 0xFF;
}
unsigned char index_reg = (addr & 0xFF) - 1;
return ((addr & 0xFF) == GB_IO_BGPD?
gb->background_palletes_data :
gb->sprite_palletes_data)[gb->io_registers[index_reg] & 0x3F];
}
case GB_IO_KEY1:
if (!gb->cgb_mode) {
return 0xFF;
}
return (gb->io_registers[GB_IO_KEY1] & 0x7F) | (gb->cgb_double_speed? 0xFE : 0x7E);
default:
if ((addr & 0xFF) >= GB_IO_NR10 && (addr & 0xFF) <= GB_IO_WAV_END) {
return apu_read(gb, addr & 0xFF);
}
return 0xFF;
}
/* Hardware registers */
return 0;
}
if (addr == 0xFFFF) {
/* Interrupt Mask */
return gb->interrupt_enable;
}
/* HRAM */
return gb->hram[addr - 0xFF80];
}
static GB_read_function_t * const read_map[] =
{
read_rom, read_rom, read_rom, read_rom, /* 0XXX, 1XXX, 2XXX, 3XXX */
read_mbc_rom, read_mbc_rom, read_mbc_rom, read_mbc_rom, /* 4XXX, 5XXX, 6XXX, 7XXX */
read_vram, read_vram, /* 8XXX, 9XXX */
read_mbc_ram, read_mbc_ram, /* AXXX, BXXX */
read_ram, read_banked_ram, /* CXXX, DXXX */
read_high_memory, read_high_memory, /* EXXX FXXX */
};
unsigned char read_memory(GB_gameboy_t *gb, unsigned short addr)
{
if (addr < 0xFF00 && gb->dma_cycles) {
/* Todo: can we access IO registers during DMA? */
return 0xFF;
}
return read_map[addr >> 12](gb, addr);
}
static void write_mbc(GB_gameboy_t *gb, unsigned short addr, unsigned char value)
{
if (gb->cartridge_type->mbc_type == NO_MBC) return;
switch (addr >> 12) {
case 0:
case 1:
gb->mbc_ram_enable = value == 0x0a;
break;
case 2:
bank_low:
/* Bank number, lower bits */
if (gb->cartridge_type->mbc_type == MBC1) {
value &= 0x1F;
}
if (gb->cartridge_type->mbc_type != MBC5 && !value) {
value++;
}
gb->mbc_rom_bank = (gb->mbc_rom_bank & 0x100) | value;
break;
case 3:
if (gb->cartridge_type->mbc_type != MBC5) goto bank_low;
if (value > 1) {
gb_log(gb, "Bank overflow: [%x] <- %d\n", addr, value);
}
gb->mbc_rom_bank = (gb->mbc_rom_bank & 0xFF) | value << 8;
break;
case 4:
case 5:
if (gb->cartridge_type->mbc_type == MBC1) {
if (gb->mbc_ram_banking) {
gb->mbc_ram_bank = value & 0x3;
}
else {
gb->mbc_rom_bank = (gb->mbc_rom_bank & 0x1F) | ((value & 0x3) << 5);
}
}
else {
gb->mbc_ram_bank = value;
/* Some games assume banks wrap around. We can do this if RAM size is a power of two */
if (gb->mbc_ram_bank >= gb->mbc_ram_size / 0x2000 && (gb->mbc_ram_size & (gb->mbc_ram_size - 1)) == 0 && gb->mbc_ram_size != 0) {
gb->mbc_ram_bank %= gb->mbc_ram_size / 0x2000;
}
}
break;
case 6:
case 7:
if (gb->cartridge_type->mbc_type == MBC1) {
value &= 1;
if (value & !gb->mbc_ram_banking) {
gb->mbc_ram_bank = gb->mbc_rom_bank >> 5;
gb->mbc_rom_bank &= 0x1F;
}
else if (value & !gb->mbc_ram_banking) {
gb->mbc_rom_bank = gb->mbc_rom_bank | (gb->mbc_ram_bank << 5);
gb->mbc_ram_bank = 0;
}
gb->mbc_ram_banking = value;
}
break;
}
if (gb->cartridge_type->mbc_type != MBC5 && !gb->mbc_rom_bank) {
gb->mbc_rom_bank = 1;
}
}
static void write_vram(GB_gameboy_t *gb, unsigned short addr, unsigned char value)
{
if ((gb->io_registers[GB_IO_STAT] & 0x3) == 3) {
//gb_log(gb, "Wrote %02x to %04x (VRAM) during mode 3\n", value, addr);
return;
}
gb->vram[(addr & 0x1FFF) + (unsigned short) gb->cgb_vram_bank * 0x2000] = value;
}
static void write_mbc_ram(GB_gameboy_t *gb, unsigned short addr, unsigned char value)
{
if (gb->mbc_ram_bank >= 8 && gb->mbc_ram_bank <= 0xC) {
/* RTC write*/
gb->rtc_data[gb->mbc_ram_bank - 8] = value;
gb->rtc_high |= ~0xC1; /* Not all bytes in RTC high are used. */
return;
}
unsigned int ram_index = (addr & 0x1FFF) + gb->mbc_ram_bank * 0x2000;
if (!gb->mbc_ram_enable)
{
gb_log(gb, "Write to %02x:%04x (%06x) (Disabled MBC RAM)\n", gb->mbc_ram_bank, addr, ram_index);
return;
}
if (ram_index >= gb->mbc_ram_size) {
gb_log(gb, "Write to %02x:%04x (%06x) (Unmapped MBC RAM)\n", gb->mbc_ram_bank, addr, ram_index);
return;
}
gb->mbc_ram[(addr & 0x1FFF) + gb->mbc_ram_bank * 0x2000] = value;
}
static void write_ram(GB_gameboy_t *gb, unsigned short addr, unsigned char value)
{
gb->ram[addr & 0x0FFF] = value;
}
static void write_banked_ram(GB_gameboy_t *gb, unsigned short addr, unsigned char value)
{
gb->ram[(addr & 0x0FFF) + gb->cgb_ram_bank * 0x1000] = value;
}
static void write_high_memory(GB_gameboy_t *gb, unsigned short addr, unsigned char value)
{
if (addr < 0xFE00) {
gb_log(gb, "Wrote %02x to %04x (RAM Mirror)\n", value, addr);
gb->ram[addr & 0x0FFF] = value;
return;
}
if (addr < 0xFEA0) {
if ((gb->io_registers[GB_IO_STAT] & 0x3) >= 2) {
return;
}
gb->oam[addr & 0xFF] = value;
return;
}
if (addr < 0xFF00) {
gb_log(gb, "Wrote %02x to %04x (Unused)\n", value, addr);
return;
}
if (addr < 0xFF80) {
/* Hardware registers */
switch (addr & 0xFF) {
case GB_IO_TAC:
case GB_IO_SCX:
case GB_IO_IF:
case GB_IO_TIMA:
case GB_IO_TMA:
case GB_IO_SCY:
case GB_IO_LYC:
case GB_IO_BGP:
case GB_IO_OBP0:
case GB_IO_OBP1:
case GB_IO_WY:
case GB_IO_WX:
case GB_IO_HDMA1:
case GB_IO_HDMA2:
case GB_IO_HDMA3:
case GB_IO_HDMA4:
case GB_IO_SB:
case GB_IO_DMG_EMULATION_INDICATION:
gb->io_registers[addr & 0xFF] = value;
return;
case GB_IO_LCDC:
if ((value & 0x80) && !(gb->io_registers[GB_IO_LCDC] & 0x80)) {
gb->display_cycles = 0;
}
gb->io_registers[GB_IO_LCDC] = value;
return;
case GB_IO_STAT:
/* Delete previous R/W bits */
gb->io_registers[GB_IO_STAT] &= 7;
/* Set them by value */
gb->io_registers[GB_IO_STAT] |= value & ~7;
/* Set unused bit to 1 */
gb->io_registers[GB_IO_STAT] |= 0x80;
return;
case GB_IO_DIV:
gb->io_registers[GB_IO_DIV] = 0;
return;
case GB_IO_JOYP:
gb->io_registers[GB_IO_JOYP] &= 0x0F;
gb->io_registers[GB_IO_JOYP] |= value & 0xF0;
return;
case GB_IO_BIOS:
gb->bios_finished = true;
return;
case GB_IO_DMG_EMULATION:
if (gb->is_cgb && !gb->bios_finished) {
gb->cgb_mode = value != 4; /* The real "contents" of this register aren't quite known yet. */
}
return;
case GB_IO_DMA:
if (value <= 0xD0) {
for (unsigned char i = 0xA0; i--;) {
gb->oam[i] = read_memory(gb, (value << 8) + i);
}
}
/* Todo: measure this value */
gb->dma_cycles = 640;
return;
case GB_IO_SVBK:
if (!gb->cgb_mode) {
return;
}
gb->cgb_ram_bank = value & 0x7;
if (!gb->cgb_ram_bank) {
gb->cgb_ram_bank++;
}
return;
case GB_IO_VBK:
if (!gb->cgb_mode) {
return;
}
gb->cgb_vram_bank = value & 0x1;
return;
case GB_IO_BGPI:
case GB_IO_OBPI:
if (!gb->is_cgb) {
return;
}
gb->io_registers[addr & 0xFF] = value;
return;
case GB_IO_BGPD:
case GB_IO_OBPD:
if (!gb->is_cgb) {
return;
}
unsigned char index_reg = (addr & 0xFF) - 1;
((addr & 0xFF) == GB_IO_BGPD?
gb->background_palletes_data :
gb->sprite_palletes_data)[gb->io_registers[index_reg] & 0x3F] = value;
palette_changed(gb, (addr & 0xFF) == GB_IO_BGPD, gb->io_registers[index_reg] & 0x3F);
if (gb->io_registers[index_reg] & 0x80) {
gb->io_registers[index_reg]++;
gb->io_registers[index_reg] |= 0x80;
}
return;
case GB_IO_KEY1:
if (!gb->is_cgb) {
return;
}
gb->io_registers[GB_IO_KEY1] = value;
return;
case GB_IO_HDMA5:
if ((value & 0x80) == 0 && gb->hdma_on_hblank) {
gb->hdma_on_hblank = false;
return;
}
gb->hdma_on = (value & 0x80) == 0;
gb->hdma_on_hblank = (value & 0x80) != 0;
gb->io_registers[GB_IO_HDMA5] = value;
gb->hdma_current_src = (gb->io_registers[GB_IO_HDMA1] << 8) | (gb->io_registers[GB_IO_HDMA2] & 0xF0);
gb->hdma_current_dest = (gb->io_registers[GB_IO_HDMA3] << 8) | (gb->io_registers[GB_IO_HDMA4] & 0xF0);
gb->hdma_steps_left = (gb->io_registers[GB_IO_HDMA5] & 0x7F) + 1;
gb->hdma_cycles = 0;
return;
case GB_IO_SC:
if ((value & 0x80) && (value & 0x1) ) {
gb->io_registers[GB_IO_SB] = 0xFF;
gb->io_registers[GB_IO_IF] |= 0x8;
}
return;
default:
if ((addr & 0xFF) >= GB_IO_NR10 && (addr & 0xFF) <= GB_IO_WAV_END) {
apu_write(gb, addr & 0xFF, value);
return;
}
if (gb->io_registers[addr & 0xFF] != 0x37) {
gb_log(gb, "Wrote %02x to %04x (HW Register)\n", value, addr);
}
gb->io_registers[addr & 0xFF] = 0x37;
return;
}
}
if (addr == 0xFFFF) {
/* Interrupt mask */
gb->interrupt_enable = value & 0x1F;
return;
}
/* HRAM */
gb->hram[addr - 0xFF80] = value;
}
static GB_write_function_t * const write_map[] =
{
write_mbc, write_mbc, write_mbc, write_mbc, /* 0XXX, 1XXX, 2XXX, 3XXX */
write_mbc, write_mbc, write_mbc, write_mbc, /* 4XXX, 5XXX, 6XXX, 7XXX */
write_vram, write_vram, /* 8XXX, 9XXX */
write_mbc_ram, write_mbc_ram, /* AXXX, BXXX */
write_ram, write_banked_ram, /* CXXX, DXXX */
write_high_memory, write_high_memory, /* EXXX FXXX */
};
void write_memory(GB_gameboy_t *gb, unsigned short addr, unsigned char value)
{
if (addr < 0xFF00 && gb->dma_cycles) {
/* Todo: can we access IO registers during DMA? */
return;
}
write_map[addr >> 12](gb, addr, value);
}
void hdma_run(GB_gameboy_t *gb)
{
if (!gb->hdma_on) return;
while (gb->hdma_cycles >= 8) {
gb->hdma_cycles -= 8;
// The CGB bios uses the dest in "absolute" space, while some games use it relative to VRAM.
// This "normalizes" the dest to the CGB address space.
gb->hdma_current_dest &= 0x1fff;
gb->hdma_current_dest |= 0x8000;
if ((gb->hdma_current_src < 0x8000 || (gb->hdma_current_src >= 0xa000 && gb->hdma_current_src < 0xe000))) {
for (unsigned char i = 0; i < 0x10; i++) {
write_memory(gb, gb->hdma_current_dest + i, read_memory(gb, gb->hdma_current_src + i));
}
}
else {
gb->halted = false;
}
gb->hdma_current_src += 0x10;
gb->hdma_current_dest += 0x10;
if(--gb->hdma_steps_left == 0){
gb->hdma_on = false;
gb->hdma_on_hblank = false;
gb->io_registers[GB_IO_HDMA5] &= 0x7F;
break;
}
if (gb->hdma_on_hblank) {
gb->hdma_on = false;
break;
}
}
}
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