Merge pull request #7 from amw-zero/controller2

Controller2

src/bin/main.rs

@@ -28,13 +28,27 @@
 extern crate emu6502;
 
 use emu6502::machine;
+use emu6502::address::Address;
 
 fn main() {
     let mut machine = machine::Machine::new();
+
+    // "Load" a program
+    machine.memory.set_byte(&Address(0), 0x69); // ADC immediate opcode
+    machine.memory.set_byte(&Address(1), 0x07); // Immediate operand
+    machine.memory.set_byte(&Address(2), 0x69); // ADC immediate opcode
+    machine.memory.set_byte(&Address(3), 0x08); // ADC immediate opcode
+
+    // Obviously this will run the full program, just
+    // executing a finite num of instructions for simplicity
+    // right now.
+    for _ in range(0u, 2u) {
+        let raw_instruction = machine.fetch_instruction();
+        let instruction = machine.decode_instruction(raw_instruction);
+        machine.execute_instruction(instruction);
+    }
     
-    println!("A: {}", machine.registers.accumulator);
+    println!("{}", machine);
-    println!("add_with_carry(1)");
+
-    machine.add_with_carry(1);
-    println!("A: {}", machine.registers.accumulator);
 }
 

src/instruction.rs

@@ -48,7 +48,9 @@ pub enum Instruction
       //                                  NV BDIZC A X Y S PC M
       //
       //                                | outputs               | inputs
-{ ADC // ADd with Carry................ | NV ...ZC A            = A + M + C
+{ 
+  ADC(i8) // ADd with Carry............ | NV ...ZC A            = A + M + C
+
 , AND // logical AND (bitwise)......... | N. ...Z. A            = A && M
 , ASL // Arithmetic Shift Left......... | N. ...ZC A            = M << 1
 , BCC // Branch if Carry Clear......... | .. .....         PC   = !C

src/machine.rs

@@ -25,6 +25,10 @@
 // ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 // POSSIBILITY OF SUCH DAMAGE.
 
+use address::AddressDiff;
+use std::fmt;
+use instruction::Instruction;
+use instruction::{ADC, NOP};
 use memory::Memory;
 use registers::{ Registers, Status, StatusArgs };
 use registers::{ ps_negative, ps_overflow, ps_zero, ps_carry };
@@ -45,6 +49,35 @@ impl Machine {
     pub fn reset(&mut self) {
     	*self = Machine::new();
     }
+
+    pub fn fetch_instruction(&mut self) -> i8  {
+        let instr = self.memory.get_byte(&self.registers.program_counter);
+
+        // Will need smarter logic to fetch the correct number of bytes 
+        // for instruction
+        self.registers.program_counter = self.registers.program_counter +  AddressDiff(1);
+        instr as i8
+    } 
+
+    pub fn decode_instruction(&mut self, raw_instruction: i8) -> Instruction {
+        match raw_instruction {
+            0x69 => ADC(self.fetch_instruction()),
+            _    => NOP 
+        }
+    }    
+        
+    pub fn execute_instruction(&mut self, instruction: Instruction) {
+        match instruction {
+            ADC(immediate) => { 
+                println!("executing add with carry");
+                self.add_with_carry(immediate);
+            },
+            NOP => {
+                println!("nop instr");
+            }
+            _ => println!("attempting to execute unimplemented instruction")
+        };
+    }
     
     // TODO akeeton: Implement binary-coded decimal.
     pub fn add_with_carry(&mut self, value: i8) {
@@ -76,6 +109,12 @@ impl Machine {
     }
 }
 
+impl fmt::Show for Machine {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "Machine Dump:\n\nAccumulator: {}", self.registers.accumulator)
+    }
+}
+
 #[test]
 fn add_with_carry_test() {