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jsgb.memory.js
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jsgb.memory.js
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/*
* jsgb.debugger.js v0.02 - Memory module for JSGB, a GameBoy Emulator
* Copyright (C) 2009 Pedro Ladaria <Sonic1980 at Gmail dot com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* version 2 as published by the Free Software Foundation.
* The full license is available at http://www.gnu.org/licenses/gpl.html
*
* 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.
*
*/
var gbMemory = new Array(0x10000);
// special register mirror values and bit states
var gbRegLY = 0;
var gbRegLYC = 0;
var gbRegSCY = 0;
var gbRegSCX = 0;
var gbRegWY = 0;
var gbRegWX = 0;
var gbRegDIV = 0;
var gbRegIF = 0;
var gbRegIE = 0;
var gbRegSTAT_Mode = 0;
var gbRegSTAT_IntLYLYC = false;
var gbRegSTAT_IntMode2 = false;
var gbRegSTAT_IntMode1 = false;
var gbRegSTAT_IntMode0 = false;
var gbRegLCDC_DisplayOn = false;
var gbRegLCDC_WindowYOffs = 0;
var gbRegLCDC_WindowDisplay = false;
var gbRegLCDC_SpriteDisplay = false;
var gbRegLCDC_SpriteSize = false;
var gbRegLCDC_BackgroundYOffs = 0;
var gbRegLCDC_BackgroundXOffs = 0;
var gbRegLCDC_BgAndWinDisplay = false;
var gbRegTAC_TimerOn = false;
// special register addresses
var _P1_ = 0xFF00;
var _SC_ = 0xFF02;
var _DIV_ = 0xFF04;
var _TIMA_ = 0xFF05;
var _TMA_ = 0xFF06;
var _TAC_ = 0xFF07;
var _IF_ = 0xFF0F;
var _LCDC_ = 0xFF40;
var _STAT_ = 0xFF41;
var _SCY_ = 0xFF42;
var _SCX_ = 0xFF43;
var _LY_ = 0xFF44;
var _LYC_ = 0xFF45;
var _DMA_ = 0xFF46;
var _BGP_ = 0xFF47;
var _OBP0_ = 0xFF48;
var _OBP1_ = 0xFF49;
var _WY_ = 0xFF4A;
var _WX_ = 0xFF4B;
var _IE_ = 0xFFFF;
// start addresses
var _ROM0_ = 0x0000;
var _ROM1_ = 0x4000;
var _VRAM_ = 0x8000; // video RAM
var _BTD0_ = 0x8000; // backgroun tile data 0
var _BTD1_ = 0x8800; // backgroun tile data 1
var _BTM0_ = 0x9800; // background tile map 0
var _BTM1_ = 0x9C00; // background tile map 1
var _RAM1_ = 0xA000; // switchable RAM
var _RAM0_ = 0xC000; // internal RAM
var _ECHO_ = 0xE000; // echo of internal RAM
var _OAM_ = 0xFE00; // object attribute
function gb_Memory_Read_ROM_Only(a) {
return gbMemory[a];
}
function gb_Memory_Read_MBC1_ROM(a) {
switch (a>>12) {
case 0:
case 1:
case 2:
case 3: return gbMemory[a];
case 4:
case 5:
case 6:
case 7: return gbROM[gbROMBank1offs+a];
default: return gbMemory[a];
}
}
var MEMR = gb_Memory_Read_ROM_Only;
function MEMW(a,v) {
// Special registers+HRAM
if (a>=0xFF00) {
switch(a&0xFF) {
case 0x00: // FF00 P1 Joypad
//if(v==3)gbMemory[a]=0xF0; else // Fx->GB/GBP; 3x->SGB
gb_Read_Joypad(v);
return;
case 0x02: // FF02 SC
gbMemory[0xFF02]=0;
return;
case 0x04: // FF04 DIV
gbMemory[0xFF04]=0; // Writing any value sets it to 0.
return;
case 0x07: // FF07 TAC - TIMER CONTROL
gbMemory[0xFF07]=v;
gbRegTAC_TimerOn=((v&4)!=0);
gb_Set_Timer_Freq(v&3);
return;
case 0x0F: // FF0F IF - Interrupt Flags
gbMemory[0xFF0F]=gbRegIF=(v&31);
return;
case 0x40: // FF40 LCDC
var i=((v>>7)!=0);
if (i!=gbRegLCDC_DisplayOn) {
// TODO not sure on this
gbMemory[_LY_]=gbRegLY=gbLCDTicks=0;
//if (!i) gb_Clear_Framebuffer();
}
gbRegLCDC_DisplayOn=i;
gbRegLCDC_WindowYOffs=(v&64)?256:0;
gbRegLCDC_WindowDisplay=(v&32)?true:false;
gbRegLCDC_BackgroundXOffs=(v&16)?0:256;
gbRegLCDC_BackgroundYOffs=(v&8)?256:0;
gbRegLCDC_SpriteSize=(v&4)?16:8;
gbRegLCDC_SpriteDisplay=(v&2)?true:false;
gbRegLCDC_BgAndWinDisplay=(v&1)?true:false;
gbMemory[0xFF40]=v;
return;
case 0x41: // FF41 STAT
gbRegSTAT_Mode=v&3;
gbRegSTAT_IntLYLYC=(v&64)?true:false;
gbRegSTAT_IntMode2=(v&32)?true:false;
gbRegSTAT_IntMode1=(v&16)?true:false;
gbRegSTAT_IntMode0=(v&8)?true:false;
gbMemory[0xFF41]=v;
return;
case 0x42: // FF42 SCY
gbMemory[0xFF42]=gbRegSCY=v;
return;
case 0x43: // FF43 SCX
gbMemory[0xFF43]=gbRegSCX=v;
return;
case 0x44: // FF44 LY
gbMemory[0xFF44]=gbRegLY=0; // Writing any value sets it to 0.
return;
case 0x45: // FF45 LYC
gbMemory[0xFF45]=gbRegLYC=v;
return;
case 0x46: // FF46 DMA TRANSFER
v=v<<8; // start address of DMA
a=0xFE00; // OAM addr
while (a<0xFEA0) gbMemory[a++] = MEMR(v++);
return;
case 0x47: // FF47 BGP - Background Palette
gbMemory[0xFF47]=v;
gbBackPal[0]=v&3;
gbBackPal[1]=(v>>2)&3;
gbBackPal[2]=(v>>4)&3;
gbBackPal[3]=(v>>6)&3;
return;
case 0x48: // FF48 OBP0 - Sprite Palette 0
gbMemory[0xFF48]=v;
gbSpritePal[0][0]=v&3;
gbSpritePal[0][1]=(v>>2)&3;
gbSpritePal[0][2]=(v>>4)&3;
gbSpritePal[0][3]=(v>>6)&3;
return;
case 0x49: // FF49 OBP1 - Sprite Palette 1
gbMemory[0xFF49]=v;
gbSpritePal[1][0]=v&3;
gbSpritePal[1][1]=(v>>2)&3;
gbSpritePal[1][2]=(v>>4)&3;
gbSpritePal[1][3]=(v>>6)&3;
return;
case 0x4A: // FF4A WY
gbMemory[0xFF4A]=gbRegWY=v;
return;
case 0x4B: // FF4B WX
gbMemory[0xFF4B]=gbRegWX=v;
return;
case 0xFF: // FFFF IE - Interrupt Enable
gbMemory[0xFFFF]=gbRegIE=(v&31);
return;
default: // THE OTHERS
gbMemory[a]=v;
return;
}
}
// writing to ROM?
else if (a<0x8000) {
switch (gbCartridgeType) {
case _ROM_ONLY_:
return;
case _ROM_MBC1_:
switch (a>>12) {
// write to 2000-3FFF: select ROM bank
case 2:
case 3:
//$('STATUS').innerHTML='Select ROM Bank: '+(v&31);
gbROMBankSwitch(v&31);
return;
// write to 6000-7FFF: select MBC1 mode
case 6:
case 7:
gbMBC1Mode = v&1;
return;
// unhandled cases
default:
//$('STATUS').innerHTML='Unhandled MBC1 ROM write:\naddr: '+hex4(a)+' - val: '+hex2(v);
return;
}
default:
alert('Unknown Memory Bank Controller.\naddr: '+hex4(a)+' - val: '+hex2(v));
gb_Pause();
return;
}
}
// make changes if the new value is different
else if (gbMemory[a]!=v) {
// 8000-97FF: Tile data
if (a<0x9800) {
gbUpdateTiles=true;
gbUpdateTilesList[(a-0x8000)>>4]=true;
gbMemory[a]=v;
}
// 9800-9FFF: Tile maps
else if (a<0xA000) {
gbUpdateBackground=true;
gbUpdateBackgroundTileList[a-0x9800]=true;
gbMemory[a]=v;
}
// A000-BFFF: Switchable RAM
else if (a<0xC000) {
gbMemory[a]=v;
}
// C000-DFFF: Internal RAM
else if (a<0xE000) {
gbMemory[a]=v;
// C000-DDFF: Writes to ECHO
if (a<0xDE00) gbMemory[a+0x2000]=v;
}
// E000-FDFF: ECHO
else if (a<0xFE00) {
gbMemory[a]=v;
gbMemory[a-0x2000]=v;
}
else gbMemory[a]=v;
}
}
function where_mem(a) { // TODO rewrite this
if (a<0x4000) return 'ROM0'; else
if (a<0x8000) return 'ROM1'; else
if (a<0xA000) return 'VRAM'; else
if (a<0xC000) return 'RAM1'; else
if (a<0xE000) return 'RAM0'; else
if (a<0xFE00) return 'ECHO'; else
if (a<0xFEA0) return 'OAM '; else
if (a<0xFF00) return 'I/O '; else
if (a<0xFF4C) return 'I/O '; else
if (a<0xFF80) return 'I/O '; else
if (a<0xFFFF) return 'HRAM'; else
if (a=0xFFFF) return 'IE '; else
return ' ';
}
function gb_Init_Memory() {
var i=0x100000;
while (i) {
gbMemory[--i] = 0;
gbMemory[--i] = 0;
gbMemory[--i] = 0;
gbMemory[--i] = 0;
}
MEMW(0xFF00,0xFF); // P1
MEMW(0xFF04,0xAF); // DIV
MEMW(0xFF05,0x00); // TIMA
MEMW(0xFF06,0x00); // TMA
MEMW(0xFF07,0xF8); // TAC
MEMW(0xFF0F,0x00); // IF
MEMW(0xFF10,0x80); // NR10
MEMW(0xFF11,0xBF); // NR11
MEMW(0xFF12,0xF3); // NR12
MEMW(0xFF14,0xBF); // NR14
MEMW(0xFF16,0x3F); // NR21
MEMW(0xFF17,0x00); // NR22
MEMW(0xFF19,0xBF); // NR24
MEMW(0xFF1A,0x7F); // NR30
MEMW(0xFF1B,0xFF); // NR31
MEMW(0xFF1C,0x9F); // NR32
MEMW(0xFF1E,0xBF); // NR33
MEMW(0xFF20,0xFF); // NR41
MEMW(0xFF21,0x00); // NR42
MEMW(0xFF22,0x00); // NR43
MEMW(0xFF23,0xBF); // NR30
MEMW(0xFF24,0x77); // NR50
MEMW(0xFF25,0xF3); // NR51
MEMW(0xFF26,0xF1); // NR52 0xF1->GB; 0xF0->SGB
MEMW(0xFF40,0x91); // LCDC
MEMW(0xFF42,0x00); // SCY
MEMW(0xFF43,0x00); // SCX
MEMW(0xFF44,0x00); // LY
MEMW(0xFF45,0x00); // LYC
MEMW(0xFF47,0xFC); // BGP
MEMW(0xFF48,0xFF); // OBP0
MEMW(0xFF49,0xFF); // OBP1
MEMW(0xFF4A,0x00); // WY
MEMW(0xFF4B,0x00); // WX
MEMW(0xFFFF,0x00); // IE
}