ADDI

src/cpu.rs

@@ -11,11 +11,44 @@ impl CPU {
         }
     }
 
-    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);
+    pub fn exec_opcode(&mut self, opcode: u32) {
+        self.registers.increment_program_counter(4);
+        let bytes = opcode.to_be_bytes();
+        let inst = bytes[0] >> 2;
+        match inst {
+            0b000000 => {
+                let rd = (opcode >> 11) & 0b11111;
+                let rs = (opcode >> 21) & 0b11111;
+                let rt = (opcode >> 16) & 0b11111;
+                self.add(rd as usize, rs as usize, rt as usize);
+                if (opcode & 0b11111111111) == 0b00000100000 {
+                    todo!("Throw exception for add overflow ADDU");
+                }
+            },
+            0b001000 | 0b001001 => {
+                let rt = (opcode >> 11) & 0b11111;
+                let rs = (opcode >> 21) & 0b11111;
+                let immediate = (opcode & 0xFFFF) as i16;
+                self.addi(rt as usize, rs as usize, immediate);
+                if inst == 0b001001 {
+                    todo!("Throw exception for add overflow ADDIU");
+                }
+            },
+            _ => unreachable!(),
+        }
+    }
+
+    pub fn add(&mut self, rd: usize, rs: usize, rt: usize) {
+        let s = self.registers.get_by_number(rs);
+        let t = self.registers.get_by_number(rt);
         let result = s.wrapping_add(t);
-        self.registers.set_by_number(destination, result);
+        self.registers.set_by_number(rd, result);
+    }
+
+    pub fn addi(&mut self, rt: usize, rs: usize, immediate: i16) {
+        let s = self.registers.get_by_number(rs);
+        let result = s.wrapping_add(immediate as i64);
+        self.registers.set_by_number(rt, result);
     }
 }
 
@@ -33,6 +66,24 @@ mod cpu_instructions_tests {
         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);
+
+        cpu.registers.set_by_number(reg_s, 40);
+        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), -40);
     }
 
+    #[test]
+    fn test_addi() {
+        let mut cpu = CPU::new();
+        let reg_dest = 10;
+        let reg_s = 15;
+        cpu.registers.set_by_number(reg_s, 80);
+        cpu.addi(reg_dest, reg_s, 80);
+        assert_eq!(cpu.registers.get_by_number(reg_dest), 160);
+
+        cpu.registers.set_by_number(reg_s, 80);
+        cpu.addi(reg_dest, reg_s, -40);
+        assert_eq!(cpu.registers.get_by_number(reg_dest), 40);
+    }
 }

src/registers.rs

@@ -100,6 +100,10 @@ impl CPURegisters {
     pub fn set_program_counter(&mut self, val: i64) {
         self.program_counter.set(val);
     }
+
+    pub fn increment_program_counter(&mut self, val: i64) {
+        self.program_counter.set(self.program_counter.get().wrapping_add(val));
+    }
 }
 
 #[cfg(test)]