Fix CNROM CHR ROM size; Fail on bad ROM file size

src/cart.c

@@ -34,7 +34,7 @@ int nes_cart_init_mem(nes_cart* cart, void* mem, int len) {
     }
 
     if (0 == status) {
-        int chr_size = nes_chr_page_size * hdr->chr_size_lsb;
+        int chr_size = nes_chr_page_size * hdr->chr_size_lsb * 2;
         INES_INFO("%d KB CHR ROM", chr_size / 1024);
         cart->chr_rom = ptr;
         cart->chr_rom_banks = hdr->chr_size_lsb * 2;
@@ -51,6 +51,14 @@ int nes_cart_init_mem(nes_cart* cart, void* mem, int len) {
         }
     }
 
+    if (0 == status) {
+        if ((ptr - mem) != len) {
+            INES_ERR("Bad file size: read %d, expected %d",
+                     (int)(ptr - mem), len);
+            status = -1;
+        }
+    }
+
     if (0 == status) {
         if (hdr->flags_6 & ines_Flag_Horizontal) {
             cart->flags |= Cart_Flag_Horizontal;

src/map/cnrom.c

@@ -35,7 +35,7 @@ static void* cnrom_init(nes_mapper* nes_map, nes_cart* cart) {
         map->prg_rom       = cart->prg_rom;
         map->prg_rom_banks = cart->prg_rom_banks;
         map->chr_rom       = cart->chr_rom;
-        map->chr_rom_banks = cart->chr_rom_banks;
+        map->chr_rom_banks = cart->chr_rom_banks / 2;
         map->mirror = (cart->flags & Cart_Flag_Horizontal) ? 0 : 1;
         cnrom_reset(map);
     }