ft(interpreter): impl stosb/stosw

src/disasm.rs

@@ -252,6 +252,8 @@ impl Disassembler {
         );
         let byte = self.parse_byte()?;
         let mnemonic = match byte {
+            0xAA => RepeatableStringOperation::STOSB(Mnemonic::STOSB),
+            0xAB => RepeatableStringOperation::STOSW(Mnemonic::STOSW),
             0xA4 => RepeatableStringOperation::MOVSB(Mnemonic::MOVSB),
             0xA5 => RepeatableStringOperation::MOVSW(Mnemonic::MOVSW),
             0xA6 => RepeatableStringOperation::CMPSB(Mnemonic::CMPSB),

src/instructions.rs

@@ -53,6 +53,8 @@ pub enum RepeatableStringOperation {
     SCASW(Mnemonic),
     MOVSB(Mnemonic),
     MOVSW(Mnemonic),
+    STOSB(Mnemonic),
+    STOSW(Mnemonic),
 }
 
 impl RepeatableStringOperation {
@@ -64,13 +66,24 @@ impl RepeatableStringOperation {
             RepeatableStringOperation::SCASW(mnemonic) => mnemonic,
             RepeatableStringOperation::MOVSB(mnemonic) => mnemonic,
             RepeatableStringOperation::MOVSW(mnemonic) => mnemonic,
+            RepeatableStringOperation::STOSB(mnemonic) => mnemonic,
+            RepeatableStringOperation::STOSW(mnemonic) => mnemonic,
         }
     }
 }
 
 impl fmt::Display for RepeatableStringOperation {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        write!(f, "self.0")
+        match self {
+            RepeatableStringOperation::CMPSB(mnemonic) => write!(f, "{}", mnemonic),
+            RepeatableStringOperation::CMPSW(mnemonic) => write!(f, "{}", mnemonic),
+            RepeatableStringOperation::SCASB(mnemonic) => write!(f, "{}", mnemonic),
+            RepeatableStringOperation::SCASW(mnemonic) => write!(f, "{}", mnemonic),
+            RepeatableStringOperation::MOVSB(mnemonic) => write!(f, "{}", mnemonic),
+            RepeatableStringOperation::MOVSW(mnemonic) => write!(f, "{}", mnemonic),
+            RepeatableStringOperation::STOSB(mnemonic) => write!(f, "{}", mnemonic),
+            RepeatableStringOperation::STOSW(mnemonic) => write!(f, "{}", mnemonic),
+        }
     }
 }
 

src/interpreter/computer.rs

@@ -471,52 +471,92 @@ impl Computer {
         rep_op: RepeatableStringOperation,
         z: bool,
     ) -> Result<(), InterpreterError> {
-        while self.regs.cx.read() != 0 {
+        loop {
-            self.string_ops(rep_op.clone().get())?;
+            if self.regs.cx.read() == 0 {
-
+                break;
-            if self.flags.zf == z {
-                return Ok(());
             }
 
+            self.string_ops(rep_op.clone().get())?;
             self.regs.cx.write(self.regs.cx.read() - 1);
-            self.regs.di -= 1;
+
+            // REPZ  stop if zf == 0
+            // REPNZ stop if zf == 1
+            match rep_op {
+                RepeatableStringOperation::CMPSB(_)
+                | RepeatableStringOperation::CMPSW(_)
+                | RepeatableStringOperation::SCASB(_)
+                | RepeatableStringOperation::SCASW(_) => {
+                    if self.flags.zf != z {
+                        break;
+                    }
+                }
+                _ => {}
+            }
         }
         Ok(())
     }
 
     /// Execute string operations.
     pub fn string_ops(&mut self, mnemonic: Mnemonic) -> Result<(), InterpreterError> {
+        fn adjust_sidi(computer: &mut Computer, val: Word) {
+            if computer.flags.df {
+                computer.regs.si -= val;
+                computer.regs.di -= val;
+            } else {
+                computer.regs.si += val;
+                computer.regs.di += val;
+            }
+        }
+        // TODO: can i write this more compact?
         match mnemonic {
-            Mnemonic::CMPSB => self.cmp(
+            Mnemonic::CMPSB => {
-                ModRmTarget::Register(crate::register::Register::AL),
+                self.cmp(
-                ArithmeticOperand::Immediate(ImmediateOperand::Byte(self.read_esdi()? as Byte)),
+                    ModRmTarget::Register(crate::register::Register::AL),
-            ),
+                    ArithmeticOperand::Immediate(ImmediateOperand::Byte(self.read_esdi()? as Byte)),
-            Mnemonic::CMPSW => self.cmp(
+                )?;
-                ModRmTarget::Register(crate::register::Register::AL),
+                adjust_sidi(self, 1);
-                ArithmeticOperand::Immediate(self.read_esdi()?.into()),
+                Ok(())
-            ),
+            }
-            Mnemonic::SCASB => self.cmp(
+            Mnemonic::CMPSW => {
-                ModRmTarget::Memory(self.regs.si.into()),
+                self.cmp(
-                ArithmeticOperand::Immediate(ImmediateOperand::Byte(self.read_esdi()? as Byte)),
+                    ModRmTarget::Register(crate::register::Register::AL),
-            ),
+                    ArithmeticOperand::Immediate(self.read_esdi()?.into()),
-            Mnemonic::SCASW => self.cmp(
+                )?;
-                ModRmTarget::Memory(self.regs.si.into()),
+                adjust_sidi(self, 2);
-                ArithmeticOperand::Immediate(ImmediateOperand::Byte(self.read_esdi()? as Byte)),
+                Ok(())
-            ),
+            }
+            Mnemonic::SCASB => {
+                self.cmp(
+                    ModRmTarget::Register(crate::register::Register::AL),
+                    ArithmeticOperand::Immediate(ImmediateOperand::Byte(self.read_esdi()? as Byte)),
+                )?;
+                if self.flags.df {
+                    self.regs.di -= 1;
+                } else {
+                    self.regs.di += 1;
+                }
+                Ok(())
+            }
+            Mnemonic::SCASW => {
+                self.cmp(
+                    ModRmTarget::Register(crate::register::Register::AX),
+                    ArithmeticOperand::Immediate(ImmediateOperand::Byte(self.read_esdi()? as Byte)),
+                )?;
+                if self.flags.df {
+                    self.regs.di -= 2;
+                } else {
+                    self.regs.di += 2;
+                }
+
+                Ok(())
+            }
             Mnemonic::MOVSB => {
                 let addr =
                     self.mem_addr(self.regs.di.into(), &crate::register::SegmentRegister::ES);
                 let val = self.read(self.regs.si.into())?;
                 self.memory
                     .write_raw(addr, ImmediateOperand::Byte(val as u8))?;
-
+                adjust_sidi(self, 1);
-                if self.flags.df {
-                    self.regs.si -= 1;
-                    self.regs.di -= 1;
-                } else {
-                    self.regs.si += 1;
-                    self.regs.di += 1;
-                }
 
                 Ok(())
             }
@@ -525,14 +565,33 @@ impl Computer {
                     self.mem_addr(self.regs.di.into(), &crate::register::SegmentRegister::ES);
                 let val = self.read(self.regs.si.into())?;
                 self.memory.write_raw(addr, val.into())?;
+                adjust_sidi(self, 2);
 
+                Ok(())
+            }
+            Mnemonic::STOSB => {
+                let addr =
+                    self.mem_addr(self.regs.di.into(), &crate::register::SegmentRegister::ES);
+                let val = self.regs.ax.lower;
+                self.memory.write_raw(addr, val.into())?;
+                if self.flags.df {
+                    self.regs.di -= 1;
+                } else {
+                    self.regs.di += 1;
+                };
+
+                Ok(())
+            }
+            Mnemonic::STOSW => {
+                let addr =
+                    self.mem_addr(self.regs.di.into(), &crate::register::SegmentRegister::ES);
+                let val = self.regs.ax.read();
+                self.memory.write_raw(addr, val.into())?;
                 if self.flags.df {
-                    self.regs.si -= 2;
                     self.regs.di -= 2;
                 } else {
-                    self.regs.si += 2;
                     self.regs.di += 2;
-                }
+                };
 
                 Ok(())
             }

src/interpreter/interpreter.rs

@@ -643,8 +643,6 @@ impl Interpreter {
                 /*
                  * String Byte Operations
                  */
-                Mnemonic::STOSB => todo!(),
-                Mnemonic::STOSW => todo!(),
                 Mnemonic::LODSB => todo!(),
                 Mnemonic::LODSW => todo!(),
 
@@ -654,6 +652,8 @@ impl Interpreter {
                 Mnemonic::CMPSW => self.computer.string_ops(current_instruction.mnemonic)?,
                 Mnemonic::MOVSB => self.computer.string_ops(current_instruction.mnemonic)?,
                 Mnemonic::MOVSW => self.computer.string_ops(current_instruction.mnemonic)?,
+                Mnemonic::STOSB => self.computer.string_ops(current_instruction.mnemonic)?,
+                Mnemonic::STOSW => self.computer.string_ops(current_instruction.mnemonic)?,
 
                 /*
                  * RET