gameboy/mbc_none.cpp

#include "mbc_none.h"
#include "mem.h"
#include <stdlib.h>
#include <SDL2/SDL.h>

namespace mbc_none
{
    uint8_t bootrom[256];
    uint8_t *rom;
    uint8_t vram[8192];
    uint8_t exram[8192];
    uint8_t wram[8192];
    uint8_t hram[512];

    uint8_t tags[65536];

    uint8_t getKeypad(uint8_t value)
    {
        const uint8_t *keys = SDL_GetKeyboardState(NULL);
        value = value & 0xf0;
        if (value & 0x10) {
            if (!keys[SDL_SCANCODE_RETURN]) value = value | 0x8;
            if (!keys[SDL_SCANCODE_SPACE]) value = value | 0x4;
            if (!keys[SDL_SCANCODE_Z]) value = value | 0x2;
            if (!keys[SDL_SCANCODE_X]) value = value | 0x1;
        } else if (value & 0x20) {
            if (!keys[SDL_SCANCODE_DOWN]) value = value | 0x8;
            if (!keys[SDL_SCANCODE_UP]) value = value | 0x4;
            if (!keys[SDL_SCANCODE_LEFT]) value = value | 0x2;
            if (!keys[SDL_SCANCODE_RIGHT]) value = value | 0x1;
        } else {
            value = value | 0x0f;
        }
        return value;
    }

    uint8_t readMem(uint16_t address)
    {
        if (address < 0x8000) {
            if ( (address < 0x0100) && ((hram[0x150]&0x01)==0) ) return bootrom[address];
            return rom[address];
        } else if (address < 0xA000) {
            return vram[address - 0x8000];
        } else if (address < 0xC000) {
            return exram[address - 0xA000];
        } else if (address < 0xE000) {
            return wram[address - 0xC000];
        } else if (address < 0xFE00) {
            return wram[address - 0xE000];
        } else {
            if (address==0xFF00) {
                hram[address - 0XFE00] = getKeypad(hram[address - 0XFE00]);
            }
            return hram[address - 0XFE00];
        }
    }

    void writeMem(uint16_t address, uint8_t value)
    {
        if (address < 0x8000) {
            // Read Only Memory, you know...
            //rom[address] = value;
        } else if (address < 0xA000) {
            vram[address - 0x8000] = value;
        } else if (address < 0xC000) {
            exram[address - 0xA000] = value;
        } else if (address < 0xE000) {
            wram[address - 0xC000] = value;
        } else if (address < 0xFE00) {
            wram[address - 0xE000] = value;
        } else {
            if ( (address==0xFF50) && ((value&0x01) != 1) ) return;  //Only allow disabling boot room
            if ( (address==0xFF00) ) { value = value & 0x30; }
            if ( (address==0xFF46) ) mem::init_dma_transfer(value);
            hram[address - 0xFE00] = value;
        }
    }

    uint8_t getTag(uint16_t address)
    {
        return tags[address];
    }

    void setTag(uint16_t address, uint8_t value)
    {
        tags[address] = value;
    }

    void saveState(FILE* f)
    {

    }

    void loadState(FILE *f)
    {

    }

    uint8_t* rawPtr(uint16_t address)
    {
        if (address < 0x8000) {
            if ( (address < 0x0100) && ((hram[0x150]&0x01)==0) ) return &bootrom[address];
            return &rom[address];
        } else if (address < 0xA000) {
            return &vram[address - 0x8000];
        } else if (address < 0xC000) {
            return &exram[address - 0xA000];
        } else if (address < 0xE000) {
            return &wram[address - 0xC000];
        } else if (address < 0xFE00) {
            return &wram[address - 0xE000];
        } else {
            return &hram[address - 0XFE00];
        }
    }

    void reset()
    {
        FILE *f = fopen("dmg_boot.bin", "rb");
        if (!f) { printf("ABORTING: 'dmg_boot.bin' not found!\n"); exit(1); }
        fseek(f, 0, SEEK_END);
        const int size = ftell(f);
        fseek(f, 0, SEEK_SET);
        fread(bootrom, size, 1, f);
        fclose(f);

        for (int i=0; i<8192; ++i) { vram[i] = 0; }
        for (int i=0; i<8192; ++i) { exram[i] = 0; }
        for (int i=0; i<8192; ++i) { wram[i] = 0; }
        for (int i=0; i<512; ++i) { hram[i] = 0; }
        for (int i=0; i<65536; ++i) { tags[i] = MEMTAG_NONE; }
    }

    void init(uint8_t *rom, uint32_t rom_size, uint32_t ram_size)
    {
        mem::readMem = mbc_none::readMem;
        mem::writeMem = mbc_none::writeMem;
        mem::getTag = mbc_none::getTag;
        mem::setTag = mbc_none::setTag;
        mem::saveState = mbc_none::saveState;
        mem::loadState = mbc_none::loadState;
        mem::reset = mbc_none::reset;
        mem::rawPtr = mbc_none::rawPtr;

        mbc_none::rom = rom;

        reset();
    }
}