Restructure to library / binary combo

src/block.rs

@@ -0,0 +1,71 @@
+use Result;
+use binread::BinReadable;
+
+#[derive(Debug)]
+pub struct Block {
+    origin: u32,
+
+    length: usize,
+    pointer: usize,
+    source: Vec<u8>
+}
+
+impl Block {
+    pub fn new(origin: u32, source: &[u8]) -> Block {
+        Block {
+            origin,
+            length: source.len(),
+            pointer: 0,
+            source: source.to_owned()
+        }
+    }
+
+    pub fn jump(&mut self, offset: i32) -> Result<()> {
+        if offset < 0 {
+            if (-offset as usize) > self.pointer {
+                return Err("Jump before block")
+            }
+            self.pointer -= -offset as usize;
+        } else {
+            if self.pointer + (offset as usize) >= self.length {
+                return Err("Jump outside of block")
+            }
+            self.pointer += offset as usize;
+        }
+        Ok(())
+    }
+
+    pub fn seek(&mut self, location: usize) -> Result<()> {
+        if location >= self.length {
+            println!("hoho {}", location);
+            return Err("Seek outside of block")
+        }
+        self.pointer = location;
+        Ok(())
+    }
+}
+
+impl BinReadable for Block {
+    fn get(&mut self) -> Result<u8> {
+        if self.pointer >= self.length {
+            return Err("EOF reached")
+        }
+        let byte = self.source[self.pointer];
+        self.pointer += 1;
+        Ok(byte)
+    }
+
+    fn len(&self) -> usize {
+        self.source.len()
+    }
+
+    fn cur(&self) -> usize {
+        self.pointer
+    }
+
+    fn slice(&mut self, len: usize) -> &[u8] {
+        let slice = &self.source[self.pointer..self.pointer+len];
+        self.pointer += len;
+        slice
+    }
+}