[cpu] Instruction parsing

src/device/cpu.rs

@@ -1,6 +1,52 @@
+use byteorder::{BigEndian, ByteOrder};
+use crate::device::cpu::Instruction::{ClearScreen, JumpTo};
 
+#[derive(Eq, PartialEq, Debug)]
 enum Instruction{
     ClearScreen,
+    /// Jump to location
     JumpTo(u16),
-
+    SetRegister(usize,u8),
+    AddValueToRegister(usize,u8),
+    SetIndex(u16),
+    ///
+    DRAW(usize,usize,u8)
 }
+impl Instruction{
+    pub fn parse_fetched_instruction(location: &[u8])->Instruction{
+        assert_eq!(location.len(),2);
+        let instruction = BigEndian::read_u16(location);
+
+        if instruction == 0xe0{
+            return ClearScreen;
+        } else if (instruction & 0x1000)==0x1000 {
+            return JumpTo(instruction & 0xfff);
+        }
+        todo!();
+    }
+}
+
+#[cfg(test)]
+mod tests{
+    use crate::device::cpu::Instruction;
+    use crate::device::cpu::Instruction::{ClearScreen, JumpTo};
+
+    #[test]
+    fn test_clear_screen(){
+        let instruction_bytes = 0x00e0_u16.to_be_bytes();
+        let ins = Instruction::parse_fetched_instruction(&instruction_bytes);
+        assert_eq!(ins,ClearScreen);
+    }
+    #[test]
+    fn test_jump_to_instruction_1(){
+        let instruction_bytes = 0x1123_u16.to_be_bytes();
+        let ins = Instruction::parse_fetched_instruction(&instruction_bytes);
+        assert_eq!(ins,JumpTo(0x123));
+    }
+    #[test]
+    fn test_jump_to_instruction_2(){
+        let instruction_bytes = 0x1faf_u16.to_be_bytes();
+        let ins = Instruction::parse_fetched_instruction(&instruction_bytes);
+        assert_eq!(ins,JumpTo(0xfaf));
+    }
+}

src/device/device.rs

@@ -47,13 +47,20 @@ impl Device{
     ];
     const FONT_DEFAULT_MEM_LOCATION_START:usize = 0x50;
     const FONT_DEFAULT_MEM_LOCATION_END:usize = 0x9F;
+    const ROM_START:usize = 0x200;
     pub fn cycle(&mut self){
 
     }
 
     pub fn set_default_font(&mut self){
+        log::info!("Loaded default font from memory");
         self.memory[Self::FONT_DEFAULT_MEM_LOCATION_START..=Self::FONT_DEFAULT_MEM_LOCATION_END].copy_from_slice(&Self::DEFAULT_FONT);
     }
+    /// load a rom from bytes
+    pub fn load_rom(&mut self,rom: &[u8]){
+        log::info!("Loaded ROM from memory");
+        self.memory[Self::ROM_START..].copy_from_slice(rom);
+    }
 
 }
 impl Drop for Device{
@@ -64,17 +71,18 @@ impl Drop for Device{
 
 pub struct RegisterFile {
     pub v: [u8; 0x10],
-    // program counter - only u12 technically.
+    /// program counter - only u12 technically.
     pub pc: u16,
     /// stack pointer
     pub i: u16,
 }
 
 impl RegisterFile {
+    pub const DEFAULT_PC_VALUE:u16 = Device::ROM_START as u16;
     pub fn new() -> RegisterFile {
         RegisterFile {
             v: [0; 0x10],
-            pc: 0x200,
+            pc: Self::DEFAULT_PC_VALUE,
             i: 0,
         }
     }