diff --git a/src/main.rs b/src/main.rs
index 953914e..4acaaf7 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -9,6 +9,6 @@ fn main() {
     let a : u8 = 128;
     let b : i8 = a as i8;
     let c : u8 = b as u8;
-    println!("aaa {}", c);
+    println!("aaa {c}");
     println!("read_memory : {}", Machine::read_memory(&mut m, 2, 4));
 }
diff --git a/src/simulator/machine.rs b/src/simulator/machine.rs
index c8a6fd6..44888f4 100644
--- a/src/simulator/machine.rs
+++ b/src/simulator/machine.rs
@@ -105,7 +105,7 @@ impl Machine {
 	/// - **address** in the memory to read
 	pub fn read_memory(machine : &mut Machine, size : i32, address : usize) -> u64 {
 		if ![1, 2, 4, 8].contains(&size) {
-			panic!("ERROR read_memory : wrong size parameter {}, must be (1, 2, 4 or 8)", size);
+			panic!("ERROR read_memory : wrong size parameter {size}, must be (1, 2, 4 or 8)");
 		}
 
 		let mut ret: u64 = 0;
@@ -128,11 +128,11 @@ impl Machine {
 	/// - **value** data to be written
 	pub fn write_memory(machine: &mut Machine, size: i32, address: usize, value: u64) {
 		if ![1, 2, 4, 8].contains(&size) {
-			panic!("ERROR write_memory: WRONG `size` PARAMETER ({}), must be 1, 2, 4 or 8", size)
+			panic!("ERROR write_memory: WRONG `size` PARAMETER ({size}), must be 1, 2, 4 or 8")
 		}
 		for i in 0..size as usize {
 			let inv_i = size as usize - i - 1;
-			machine.main_memory[address + i as usize] = ((value & 0xff << (8 * inv_i)) >> (inv_i * 8)) as u8;
+			machine.main_memory[address + i] = ((value & 0xff << (8 * inv_i)) >> (inv_i * 8)) as u8;
 		}
 	}
 
@@ -392,9 +392,36 @@ impl Machine {
 				}
 			},
 			//******************************************************************************************
+			// Treatment for OPIW INSTRUCTIONS
+			RISCV_OPIW => {
+				let local_data = machine.int_reg.get_reg(inst.rs1 as usize);
+				match inst.funct3 {
+					RISCV_OPIW_ADDIW => {
+						let result = local_data + inst.imm12_I_signed as i64;
+						machine.int_reg.set_reg(inst.rd as usize, result);
+					},
+					RISCV_OPIW_SLLIW => {
+						let result = local_data << inst.shamt;
+						machine.int_reg.set_reg(inst.rd as usize, result);
+					},
+					RISCV_OPIW_SRW => {
+						let result;
+						if inst.funct7 == RISCV_OPIW_SRW_SRLIW {
+							result = (local_data >> inst.shamt) & machine.shiftmask[32 + inst.shamt as usize] as i64;
+						} else { // SRAIW
+							result = local_data >> inst.shamt;
+						}
+						machine.int_reg.set_reg(inst.rd as usize, result);
+					},
+					_ => {
+						panic!("In OPI switch case, this should never happen... Instr was {}\n", inst.value);
+					}
+				}
+			},
+			//******************************************************************************************
     		// Treatment for: OPW INSTRUCTIONS
 			RISCV_OPW => {
-				if inst.funct7 == 1 {
+				if inst.funct7 == 1 { // rv64m
 					let local_data_a = machine.int_reg.get_reg(inst.rs1 as usize) & 0xffffffff;
 					let local_data_b = machine.int_reg.get_reg(inst.rs2 as usize) & 0xffffffff;
 					let local_data_a_unsigned = machine.int_reg.get_reg(inst.rs1 as usize) & 0xffffffff;
@@ -421,7 +448,7 @@ impl Machine {
 							panic!("this instruction ({}) doesn't exists", inst.value);
 						}
 					}
-				} else {
+				} else { // others rv64 OPW operations
 					let local_dataa = machine.int_reg.get_reg(inst.rs1 as usize) & 0xffffffff;
 					let local_datab = machine.int_reg.get_reg(inst.rs2 as usize) & 0xffffffff;
 
diff --git a/src/simulator/mod.rs b/src/simulator/mod.rs
index 266e97a..16e19a5 100644
--- a/src/simulator/mod.rs
+++ b/src/simulator/mod.rs
@@ -303,7 +303,7 @@ pub mod global {
     /// 
     /// Shift right logical immediate word (RV64I only)
     /// 
-    /// `SLLIW rd, rs1, imm12` => `rd <- rs1 >> imm12`
+    /// `SLLIW rd, rs1, imm12` => `rd <- rs1 >> shamt`
     pub const RISCV_OPIW_SLLIW: u8 = 0x1;
     
     /// Shift right immediate instructions (logical or arithmetic depend of func7)
@@ -312,7 +312,7 @@ pub mod global {
     /// 
     /// Shift right logical immediate word (RV64I only)
     /// 
-    /// `SRLIW rd, rs1, imm12` => `rd <- rs1 >> imm12`
+    /// `SRLIW rd, rs1, imm12` => `rd <- rs1 >> shamt`
     /// 
     /// Complete left bits by a zero, should be used with an unsigned value in most case
     pub const RISCV_OPIW_SRW_SRLIW: u8 = 0x0;
@@ -320,7 +320,7 @@ pub mod global {
     /// 
     /// Shift right arithmetic immediate word (RV64I only)
     /// 
-    /// `SRAIW rd, rs1, imm12` => `rd <- rs1 >> imm12`
+    /// `SRAIW rd, rs1, imm12` => `rd <- rs1 >> shamt`
     /// 
     /// Keep sign bit
     pub const RISCV_OPIW_SRW_SRAIW: u8 = 0x20;
diff --git a/src/simulator/print.rs b/src/simulator/print.rs
index 68a8b89..4bad5ad 100644
--- a/src/simulator/print.rs
+++ b/src/simulator/print.rs
@@ -91,9 +91,9 @@ pub fn print(ins: Instruction, pc: i32) -> String { //TODO pc should be u64
         RISCV_OPIW => {
             if ins.funct3 == RISCV_OPIW_SRW {
                 if ins.funct7 == RISCV_OPIW_SRW_SRLIW {
-                    format!("srlwi\t{}, {}, {}", REG_X[rd], REG_X[rs1], REG_X[rs2])
+                    format!("srliw\t{}, {}, {}", REG_X[rd], REG_X[rs1], REG_X[rs2])
                 } else {
-                    format!("srawi\t{}, {}, {}", REG_X[rd], REG_X[rs1], REG_X[rs2])
+                    format!("sraiw\t{}, {}, {}", REG_X[rd], REG_X[rs1], REG_X[rs2])
                 }
             } else if ins.funct3 == RISCV_OPIW_SLLIW {
                 format!("{}\t{}, {}, {}", NAMES_OPI[ins.funct3 as usize], REG_X[rd], REG_X[rs1], REG_X[rs2])