diff --git a/bench/tests/op/add.s b/bench/tests/op/add.s
index 9dcef14..95a19b1 100644
--- a/bench/tests/op/add.s
+++ b/bench/tests/op/add.s
@@ -3,7 +3,7 @@
 _start:
     lui x2, 0xdead0
     lui x3, 0x0
-    lui x4, 0x1
+    addi x4, x0, 0x1
     addi x5, x0, (-1)
 
     # Add 0
diff --git a/bench/tests/op/slt.s b/bench/tests/op/slt.s
index 3f380ec..531da56 100644
--- a/bench/tests/op/slt.s
+++ b/bench/tests/op/slt.s
@@ -1,4 +1,4 @@
-# expected: 00000000, 00000001, 00000001, 00000000
+# expected: 00000000, 00000001, 00000000, 00000000
     .text
 _start:
     addi x1, x0, (-1)
diff --git a/src/main/scala/projet/ControlUnit.scala b/src/main/scala/projet/ControlUnit.scala
index 363d981..b573d86 100644
--- a/src/main/scala/projet/ControlUnit.scala
+++ b/src/main/scala/projet/ControlUnit.scala
@@ -10,8 +10,12 @@ class CUInterface extends Bundle {
     val alu_opcode = Output(AluOpCode())
     val optype = Output(OpType())
 
+    // Muxers
+    // The naming convention is as follows : mux_xxx_yyy.
+    // If the signal is hot, xxx is selected otherwise yyy is selected
     val mux_alu_imm = Output(Bool())
     val mux_rega_pc = Output(Bool())
+    val mux_regb_imm = Output(Bool())
 }
 
 object OpType extends ChiselEnum {
@@ -26,7 +30,7 @@ object OpCode extends ChiselEnum {
     // Type I + Type IR
 
     // Instruction format
-    //    xxx rd, rs1 imm
+    //    xxx rd, rs1, imm
     // Perfomrs some operation with rs1 and immediate
     // and writes back to a register
 
@@ -34,6 +38,14 @@ object OpCode extends ChiselEnum {
     // slti, sltiu
     val OpImm = 0b0010011.U
 
+    // Instruction format
+    //    xxx rd, rs1, rs2
+    // Perfomrs some operation with rs1 and rd2
+    // and writes back to a register
+
+    // add, and, or, xor, sll, srl, sra, slt, stlu
+    val OpR = 0b0110011.U;
+
 }
 
 
@@ -45,6 +57,7 @@ class ControlUnit() extends Module {
     io.optype := OpType.U
     io.mux_alu_imm := true.B;
     io.mux_rega_pc := true.B;
+    io.mux_regb_imm := true.B;
 
     // Decode instruction
     val opcode = io.instruction(6, 0);
@@ -54,15 +67,16 @@ class ControlUnit() extends Module {
     switch(opcode) {
 
         // U instructions
-        is(OpCode.LUI) {
-            io.reg_file_we := true.B
-            io.mux_alu_imm := false.B
+        is(OpCode.LUI) { 
+            io.reg_file_we := true.B // Write to regfile
+            io.mux_alu_imm := false.B // Send immy directly to refile
             io.optype := OpType.U
         }
         is(OpCode.AUIPC) {
             io.alu_opcode := AluOpCode.Add 
-            io.reg_file_we := true.B
-            io.mux_rega_pc := false.B
+            io.reg_file_we := true.B // Write to regfile
+            io.mux_rega_pc := false.B // Send PC to ALU A
+            io.mux_alu_imm := false.B; // Send immu to ALU B
             io.optype := OpType.U
         }
 
@@ -71,8 +85,16 @@ class ControlUnit() extends Module {
             io.reg_file_we := true.B
             opImm(funct3, funct7, io);
         }
+        
+        // OpR instructions
+        is(OpCode.OpR) {
+            io.reg_file_we := true.B
+            opR(funct3, funct7, io);
+        }
     }
 
+
+
     // Implements functions for all instruction of the opImm kind
     def opImm(funct3: UInt, funct7: UInt, io: CUInterface) =
     {
@@ -98,6 +120,10 @@ class ControlUnit() extends Module {
         val SRLI = 0b0000000.U 
         val SRAI = 0b0100000.U 
       }
+
+      io.mux_regb_imm := false.B; // OpImm are operations with imm, so send imm to ALU
+      io.mux_alu_imm := true.B;
+      io.mux_rega_pc := true.B;
        switch(funct3)
        {
          // Type I
@@ -162,6 +188,93 @@ class ControlUnit() extends Module {
           }
        }
     }
+
+
+    // Implements functions for all instruction of the opR kind
+    def opR(funct3: UInt, funct7: UInt, io: CUInterface) =
+    {
+      // Meaning of Funct3 in the context of an OpR instruction
+      object Funct3 extends ChiselEnum
+      {
+        // Type I
+        val ADD = 0b000.U
+        val AND = 0b111.U
+        val OR = 0b110.U
+        val XOR = 0b100.U
+        val SLL = 0b001.U
+        val SLT = 0b010.U
+        val SLTU = 0b011.U
+
+        // Arithmetic op (discriminate by Funct7)
+        val SRL_SRA = 0b101.U
+      }
+
+      // Meaning of Funct7 in the context of SHIFTR IR instructions 
+      object IRFunct7 extends ChiselEnum
+      {
+        val SRL = 0b0000000.U 
+        val SRA = 0b0100000.U 
+      }
+
+      io.mux_regb_imm := true.B; // OpImm are operations with imm, so send imm to ALU
+      io.mux_rega_pc := true.B;
+      io.mux_alu_imm := true.B;
+       switch(funct3)
+       {
+         // Type I
+          is(Funct3.ADD)
+          {
+            io.alu_opcode := AluOpCode.Add 
+          }
+
+          is(Funct3.AND)
+          {
+            io.alu_opcode := AluOpCode.And
+          }
+
+          is(Funct3.OR)
+          {
+            io.alu_opcode := AluOpCode.Or
+          }
+
+          is(Funct3.XOR)
+          {
+            io.alu_opcode := AluOpCode.Xor
+          }
+
+          is(Funct3.SLL)
+          {
+            io.alu_opcode := AluOpCode.ShiftLeft
+          }
+
+          is(Funct3.SLT)
+          {
+            io.alu_opcode := AluOpCode.LessThanSigned
+          }
+
+          is(Funct3.SLTU)
+          {
+            io.alu_opcode := AluOpCode.LessThanUnsigned
+          }
+
+          // Type IR
+          is(Funct3.SRL_SRA)
+          {
+            switch(funct7)
+            {
+              is(IRFunct7.SRL)
+              {
+                io.alu_opcode := AluOpCode.ShiftRight
+              }
+
+              is(IRFunct7.SRA)
+              {
+                io.alu_opcode := AluOpCode.ShiftArithmeticRight
+              }
+            }
+          }
+       }
+    }
 }
 
 
diff --git a/src/main/scala/projet/Rv32i.scala b/src/main/scala/projet/Rv32i.scala
index fcc27ef..1dcf7f6 100644
--- a/src/main/scala/projet/Rv32i.scala
+++ b/src/main/scala/projet/Rv32i.scala
@@ -64,7 +64,7 @@ class Rv32i(sim: Boolean = true) extends Module {
         reg_file.io.rs1_data,
         execute_pc
     );
-    alu.io.b := imm;
+    alu.io.b := Mux(control_unit.io.mux_regb_imm, reg_file.io.rs2_data, imm);
 
     reg_file.io.rd_data := Mux(control_unit.io.mux_alu_imm, alu.io.out, imm);