Finish ppu, and mbc1 mapping

lib/cart.c

@@ -6,10 +6,39 @@ typedef struct {
     u32 rom_size;
     u8 *rom_data;
     rom_header *header;
+
+    //mbc1 data
+    bool ram_enabled;
+    bool ram_banking;
+
+    u8 *rom_bank_x;
+    u8 banking_mode;
+
+    u8 rom_bank_value;
+    u8 ram_bank_value;
+
+    u8 *ram_bank;
+    u8 *ram_banks[16];
+
+    //battery
+    bool battery;
+    bool need_save;
 } cart_context;
 
 static cart_context ctx;
 
+bool cart_need_save () {
+    return ctx.need_save;
+}
+
+bool cart_mbc1() {
+    return BETWEEN(ctx.header->type, 1, 3);
+}
+
+bool cart_battery() {
+    return ctx.header->type == 3;
+}
+
 static const char *ROM_TYPES[] = {
     "ROM ONLY",
     "MBC1",
@@ -132,6 +161,23 @@ const char *cart_lic_name() {
     return "UNKNOWN";
 }
 
+void cart_setup_bamking() {
+    for (int i=0; i<16; i++) {
+        ctx.ram_banks[1] = 0;
+
+        if((ctx.header->ram_size == 2 && i == 0) || 
+            (ctx.header->ram_size == 3 && i < 4) ||
+            (ctx.header->ram_size == 5 && i < 8) ||
+            (ctx.header->ram_size == 4)) {
+            ctx.ram_banks[i] = malloc(0x2000);
+            memset(ctx.ram_banks[i], 0, 0x2000);
+        }
+    }
+
+    ctx.ram_bank = ctx.ram_banks[0];
+    ctx.rom_bank_x = ctx.rom_data + 0x4000;
+}
+
 bool cart_load(char *cart) {
     snprintf(ctx.filename, sizeof(ctx.filename), "%s", cart);
     FILE *fp = fopen(cart, "r");
@@ -153,6 +199,8 @@ bool cart_load(char *cart) {
 
     ctx.header = (rom_header *)(ctx.rom_data + 0x100);
     ctx.header->title[15] = 0;
+    ctx.battery = cart_battery();
+    ctx.need_save = false;
 
     printf("Cartridge Loaded:\n");
     printf("\t Title    : %s\n", ctx.header->title);
@@ -162,6 +210,8 @@ bool cart_load(char *cart) {
     printf("\t LIC Code : %2.2X (%s)\n", ctx.header->lic_code, cart_lic_name());
     printf("\t ROM Vers : %2.2X\n", ctx.header->version);
 
+    cart_setup_bamking();
+
     u16 x = 0;
     for (u16 i=0X0134; i<=0X014C; i++) {
         x = x - ctx.rom_data[i] -1;
@@ -172,17 +222,119 @@ bool cart_load(char *cart) {
     if((x & 0xFF) != ctx.header->checksum) {
         fprintf(stderr, "WARNING!!! The header checksum does not match! ROM may be corrupt or invalid!\n");
     }
+
+    if(ctx.battery) {
+        cart_battery_load();
+    }
     
     return true;
 }
 
 u8 cart_read(u16 address){
-    //for now ROM ONLY type supported...
+    if(!cart_mbc1() || address < 0x4000) {
+        return ctx.rom_data[address];
+    }
+
+    if((address & 0xE000) == 0xA000) {
+        if (!ctx.ram_enabled) {
+            return 0xFF;
+        }
+
+        if(!ctx.ram_bank) {
+            return 0xFF;
+        }
+
+        return ctx.ram_bank[address - 0xA000];
+    }
+
+    return ctx.rom_bank_x[address - 0x4000];
 
-    return ctx.rom_data[address];
 }
 
 void cart_write(u16 address, u8 value){
-    printf("UNSUPPORTED cart_write(%04X)\n", address);
-    //NO_IMPL
+    if(!cart_mbc1()) {
+        return;
+    }
+
+    if(address < 0x2000) {
+        ctx.ram_enabled = ((value & 0xF) == 0xA);
+    }
+
+    if((address & 0xE000) == 0x2000) {
+        //rom bank
+        if(value == 0) {
+            value = 1;
+        }
+
+        value &= 0b11111;
+        ctx.rom_bank_value = value;
+        ctx.rom_bank_x = ctx.rom_data + (0x4000 * ctx.rom_bank_value);
+    }
+
+    if((address & 0xE000) == 0x4000) {
+        //ram bank number
+        ctx.ram_bank_value = value & 0xb11;
+        if(ctx.ram_banking) {
+            if(cart_need_save) {
+                cart_battery_save();
+            }
+            ctx.ram_bank = ctx.ram_banks[ctx.ram_bank_value];
+        }
+    }
+
+    if((address & 0xE000) == 0x6000) {
+        //bamking mode select
+
+        ctx.banking_mode = value & 1;
+
+        ctx.ram_banking = ctx.banking_mode;
+
+        if (ctx.ram_banking) {
+            if(cart_need_save) {
+                cart_battery_save();
+            }
+            ctx.ram_bank = ctx.ram_banks[ctx.ram_bank_value];
+        }
+    }
+
+    if((address & 0xE000) == 0xA000) {
+        if(!ctx.ram_enabled)
+            return;
+
+        if(!ctx.ram_bank)
+            return;
+
+        ctx.ram_bank[address - 0xA000] = value;
+
+        if(ctx.battery) {
+            ctx.need_save = true;
+        }
+    }
+}
+
+bool cart_battery_load(){
+    char fn[1048];
+    sprintf(fn, "%s.battery", ctx.filename);
+    FILE *fp = fopen(fn, "rb");
+
+    if(!fp) {
+        fprintf(stderr, "unable to open: %s\n", fn);
+    }
+
+    fread(ctx.ram_bank, 0x2000, 1, fp);
+    fclose(fp);
+}
+
+bool cart_battery_save(){
+    char fn[1048];
+    sprintf(fn, "%s.battery", ctx.filename);
+    FILE *fp = fopen(fn, "wb");
+
+    if(!fp) {
+        fprintf(stderr, "unable to open: %s\n", fn);
+    }
+
+    fwrite(ctx.ram_bank, 0x2000, 1, fp);
+    fclose(fp);
+
 }