Support reading VBX files in cart

src/emulator/cart.rs

@@ -34,9 +34,14 @@ impl Cart {
             .truncate(false)
             .open(sram_path(file_path, sim_id))?;
 
+        let sram_file_size = if contents.sram_small_bus {
+            contents.sram_size * 2
+        } else {
+            contents.sram_size
+        };
         let sram = if sram_file.metadata()?.len() == 0 {
             // new SRAM file, randomize the contents
-            let mut sram = vec![0; contents.sram_size];
+            let mut sram = vec![0; sram_file_size];
             let mut rng = rand::rng();
             for dst in sram
                 .iter_mut()
@@ -46,9 +51,9 @@ impl Cart {
             }
             sram
         } else {
-            let mut sram = Vec::with_capacity(contents.sram_size);
+            let mut sram = Vec::with_capacity(sram_file_size);
             sram_file.read_to_end(&mut sram)?;
-            sram.resize(contents.sram_size, 0);
+            sram.resize(sram_file_size, 0);
             sram
         };