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82 lines
2.4 KiB
82 lines
2.4 KiB
#include "cartridge.h"
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#include "bus.h"
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HEADER Header;
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byte PRGROM[0xFFFF];
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byte CHRROM[0xFFFF];
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word not_handling_this = 0x100; //0xFF + 1
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word romStartAddress = 0x0;
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void loadRomfileHeader(FILE * romfile){
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byte verificationToken[3] = "NES";
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for(byte i = 0; i < 3; i++)
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if(verificationToken[i] != getc(romfile)){
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fprintf(stderr, "ERR: This is not a NES Rom!!!\n");
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exit(EXIT_FAILURE);
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return;
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}
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getc(romfile); //get over the DOS EOF byte
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Header.PRG_BANKS = getc(romfile);
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Header.CHR_BANKS = getc(romfile);
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for(byte i = 0; i < 5; i++){
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Header.flags.array[i] = getc(romfile);
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}
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for(byte i = 0; i < 4; i++){ //Remove padding
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getc(romfile);
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}
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}
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void initBanks(char name[]){
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FILE * romfile;
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romfile = fopen(name, "rb");
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if(romfile == NULL){
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fprintf(stderr, "ERR: file \"%s\" could not be opened for reading!\n", name);
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exit(EXIT_FAILURE);
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}
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loadRomfileHeader(romfile);
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if(Header.flags.flag6.trainer) //if trainer data
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fseek(romfile, 512, SEEK_CUR);
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for(word i = 0; i < GET_PRG_BANK_SIZE(Header.PRG_BANKS); i++){
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PRGROM[i] = getc(romfile);
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}
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for(word i = 0; i < GET_CHR_BANK_SIZE(Header.CHR_BANKS); i++){
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CHRROM[i] = getc(romfile);
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}
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fclose(romfile);
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//Read rom start Address
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#define ROM_START_VECTOR_ADDR (0xFFFC)
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romStartAddress = busRead16(ROM_START_VECTOR_ADDR);
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}
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word mapper000_Read(word address, bool ppu){
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if(!ppu){ //if not ppu talking
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if(!((address <= 0xFFFF) && (address >= 0x8000))){ //if not in the address range the mapper functions in
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return not_handling_this; //not_handling_this is a 16 bit data integer, no byte will return this ever so this is our "not handling this" return code
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}else{
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if(Header.PRG_BANKS > 1){ //32K model
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return PRGROM[address - 0x8000];
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}else{ //16K model
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return PRGROM[(address - 0x8000) % 0x3FFF];
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}
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}
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}else{ //if PPU
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if(Header.CHR_BANKS == 0) return not_handling_this; //if no CHR banks, nothing to mirror
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else if (address <= 0x2000) return CHRROM[address - 0x2000];
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else return not_handling_this;
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}
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}
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bool mapper000_Write(word address, byte data, bool ppu){
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return false; //no PRGRAM configured in this cartridge, so all writes get denied
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};
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