chunk save files by 8kb

src/processor/memory/rom.rs

@@ -12,6 +12,7 @@ mod mbcs;
 
 struct MaybeBufferedSram {
     buf: Vec<u8>,
+    length: usize,
     inner: Option<File>,
     unbuffered_writes: usize,
 }
@@ -20,7 +21,7 @@ const NUM_WRITES_TO_FLUSH: usize = 256;
 
 impl MaybeBufferedSram {
     fn new(path: Option<PathBuf>, length: usize) -> Self {
-        let mut buf = vec![0; length];
+        let mut buf = vec![0; 8 * mbcs::KB];
         let inner = if let Some(path) = path {
             if path.exists() {
                 let mut writer = OpenOptions::new()
@@ -28,7 +29,8 @@ impl MaybeBufferedSram {
                     .read(true)
                     .open(path)
                     .unwrap();
-                writer.read_exact(&mut buf).unwrap();
+                // writer.read_exact(&mut buf).unwrap();
+                writer.read_to_end(&mut buf).unwrap();
                 Some(writer)
             } else {
                 let writer = OpenOptions::new()
@@ -36,7 +38,6 @@ impl MaybeBufferedSram {
                     .create_new(true)
                     .open(path)
                     .unwrap();
-                writer.set_len(length as u64).unwrap();
                 Some(writer)
             }
         } else {
@@ -45,21 +46,30 @@ impl MaybeBufferedSram {
 
         Self {
             buf,
+            length,
             inner,
             unbuffered_writes: 0,
         }
     }
 
     fn len(&self) -> usize {
-        self.buf.len()
+        self.length
     }
 
     fn get(&self, addr: usize) -> u8 {
+        if addr >= self.buf.len() {
+            0
+        } else {
             self.buf[addr]
         }
+    }
 
     fn set(&mut self, addr: usize, data: u8) {
         self.unbuffered_writes += 1;
+        if addr >= self.buf.len() {
+            self.buf
+                .resize((addr as f64 / (mbcs::KB as f64 * 8.)).ceil() as usize, 0);
+        }
         self.buf[addr] = data;
         if self.unbuffered_writes >= NUM_WRITES_TO_FLUSH {
             self.flush();

src/processor/memory/rom/mbcs.rs

@@ -11,7 +11,7 @@ pub use mbc3::Mbc3;
 pub use mbc5::Mbc5;
 pub use none::None;
 
-const KB: usize = 1024;
+pub(super) const KB: usize = 1024;
 const ROM_BANK_SIZE: usize = 16 * KB;
 const RAM_BANK_SIZE: usize = 8 * KB;