ADD instruction test

src/cpu.rs

@@ -3,3 +3,36 @@ use crate::registers::{CPURegisters};
 pub struct CPU {
     registers: CPURegisters,
 }
+
+impl CPU {
+    pub fn new() -> Self {
+        Self {
+            registers: CPURegisters::new(),
+        }
+    }
+
+    pub fn add(&mut self, destination: usize, reg_s: usize, reg_t: usize) {
+        let s = self.registers.get_by_number(reg_s);
+        let t = self.registers.get_by_number(reg_t);
+        let result = s.wrapping_add(t);
+        self.registers.set_by_number(destination, result);
+    }
+}
+
+#[cfg(test)]
+mod cpu_instructions_tests {
+    use super::*;
+
+    #[test]
+    fn test_add() {
+        let mut cpu = CPU::new();
+        let reg_dest = 10;
+        let reg_s = 15;
+        let reg_t = 20;
+        cpu.registers.set_by_number(reg_s, 80);
+        cpu.registers.set_by_number(reg_t, 80);
+        cpu.add(reg_dest, reg_s, reg_t);
+        assert_eq!(cpu.registers.get_by_number(reg_dest), 160);
+    }
+
+}

src/registers.rs

@@ -65,7 +65,7 @@ impl CPURegisters {
                 Box::new(Generic(0_i64)),
                 Box::new(Generic(0_i64)),
             ],
-            program_counter: Generic(0_i64),
+            program_counter: Generic(0xBFC00000),
         }
     }