cpu: Model Program Status Register.

src/arm7tdmi/cpu.rs

@@ -1,10 +1,11 @@
 use std::convert::TryFrom;
 use std::fmt;
 
-use crate::num_traits::FromPrimitive;
+use colored::*;
 
-use super::arm::exec;
+use super::reg_string;
 use super::arm::*;
+use super::psr::{CpuMode, CpuState, RegPSR};
 use super::sysbus::SysBus;
 
 #[derive(Debug, PartialEq)]
@@ -44,31 +45,13 @@ impl fmt::Display for CpuError {
                 "illegal instruction at address @0x{:08x} (0x{:08x})",
                 insn.pc, insn.raw
             ),
-            e => write!(f, "error: {:#x?}", e)
+            e => write!(f, "error: {:#x?}", e),
         }
     }
 }
 
 pub type CpuResult<T> = Result<T, CpuError>;
 
-#[derive(Debug, PartialEq)]
-pub enum CpuState {
-    ARM,
-    THUMB,
-}
-
-#[derive(Debug, Primitive)]
-#[repr(u8)]
-enum CpuMode {
-    User = 0b10000,
-    Fiq = 0b10001,
-    Irq = 0b10010,
-    Supervisor = 0b10011,
-    Abort = 0b10111,
-    Undefined = 0b11011,
-    System = 0b11111,
-}
-
 pub struct CpuModeContext {
     // r8-r14
     banked_gpr: [u32; 7],
@@ -79,12 +62,9 @@ pub struct CpuModeContext {
 pub struct Core {
     pub pc: u32,
     // r0-r7
-    gpr: [u32; 8],
+    gpr: [u32; 15],
-    cpsr: u32,
+    pub cpsr: RegPSR,
-
+    pub verbose: bool,
-    mode: CpuMode,
-    state: CpuState,
-    verbose: bool
 }
 
 #[derive(Debug, PartialEq)]
@@ -99,10 +79,8 @@ impl Core {
     pub fn new() -> Core {
         Core {
             pc: 0,
-            gpr: [0; 8],
+            gpr: [0; 15],
-            cpsr: 0,
+            cpsr: RegPSR::new(),
-            mode: CpuMode::System,
-            state: CpuState::ARM,
             verbose: false,
         }
     }
@@ -113,34 +91,30 @@ impl Core {
 
     pub fn get_reg(&self, reg_num: usize) -> u32 {
         match reg_num {
-            0...7 => self.gpr[reg_num],
+            0...14 => self.gpr[reg_num],
             15 => self.pc,
-            _ => unimplemented!("TODO banked registers"),
+            _ => panic!("invalid register")
+            // _ => 0x12345678 // unimplemented!("TODO banked registers"),
         }
     }
 
     pub fn set_reg(&mut self, reg_num: usize, val: u32) {
         match reg_num {
-            0...7 => self.gpr[reg_num] = val,
+            0...14 => self.gpr[reg_num] = val,
             15 => self.pc = val,
-            _ => unimplemented!("TODO banked registers"),
+            _ => panic!("invalid register")
+            // _ => unimplemented!("TODO banked registers"),
         }
     }
 
-    pub fn set_state(&mut self, s: CpuState) {
-        self.state = s;
-    }
-
     /// Resets the cpu
     pub fn reset(&mut self) {
         self.pc = 0;
-        self.cpsr = 0;
+        self.cpsr.set(0);
-        self.mode = CpuMode::System;
-        self.state = CpuState::ARM;
     }
 
     fn word_size(&self) -> usize {
-        match self.state {
+        match self.cpsr.state() {
             CpuState::ARM => 4,
             CpuState::THUMB => 2,
         }
@@ -160,7 +134,7 @@ impl Core {
     }
 
     pub fn step(&mut self, sysbus: &mut SysBus) -> CpuResult<()> {
-        let (executed_insn, pipeline_action) = match self.state {
+        let (executed_insn, pipeline_action) = match self.cpsr.state() {
             CpuState::ARM => self.step_arm(sysbus),
             CpuState::THUMB => unimplemented!("thumb not implemented :("),
         }?;
@@ -178,3 +152,16 @@ impl Core {
         Ok(())
     }
 }
+
+impl fmt::Display for Core {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        writeln!(f, "ARM7TDMI Core")?;
+        writeln!(f, "REGISTERS:")?;
+        for i in 0..16 {
+            let mut reg = reg_string(i).to_string();
+            reg.make_ascii_uppercase();
+            writeln!(f, "\t{}\t= 0x{:08x}", reg.bright_yellow(), self.get_reg(i))?;
+        }
+        write!(f, "CPSR: {}", self.cpsr)
+    }
+}

src/arm7tdmi/psr.rs

@@ -0,0 +1,200 @@
+/// The program status register
+use std::fmt;
+
+use crate::bit::BitIndex;
+use crate::num_traits::FromPrimitive;
+
+use colored::*;
+
+use super::arm::ArmCond;
+
+#[derive(Debug, PartialEq, Primitive)]
+#[repr(u8)]
+pub enum CpuState {
+    ARM = 0,
+    THUMB = 1,
+}
+
+impl fmt::Display for CpuState {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        use CpuState::*;
+        match self {
+            ARM => write!(f, "ARM"),
+            THUMB => write!(f, "THUMB"),
+        }
+    }
+}
+
+impl From<CpuState> for bool {
+    fn from(state: CpuState) -> bool {
+        match state {
+            CpuState::ARM => false,
+            CpuState::THUMB => true,
+        }
+    }
+}
+
+impl From<bool> for CpuState {
+    fn from(flag: bool) -> CpuState {
+        if flag {
+            CpuState::THUMB
+        } else {
+            CpuState::ARM
+        }
+    }
+}
+
+#[derive(Debug, Primitive)]
+#[repr(u8)]
+pub enum CpuMode {
+    User = 0b10000,
+    Fiq = 0b10001,
+    Irq = 0b10010,
+    Supervisor = 0b10011,
+    Abort = 0b10111,
+    Undefined = 0b11011,
+    System = 0b11111,
+}
+
+impl fmt::Display for CpuMode {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        use CpuMode::*;
+        match self {
+            User => write!(f, "USR"),
+            Fiq => write!(f, "FIQ"),
+            Irq => write!(f, "IRQ"),
+            Supervisor => write!(f, "SVC"),
+            Abort => write!(f, "ABT"),
+            Undefined => write!(f, "UND"),
+            System => write!(f, "SYS"),
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct RegPSR {
+    raw: u32,
+}
+
+const RESERVED_BIT_MASK: u32 = 0x0fffff00;
+fn clear_reserved(n: u32) -> u32 {
+    n & !RESERVED_BIT_MASK
+}
+
+impl RegPSR {
+    pub fn new() -> RegPSR {
+        let mut psr = RegPSR { raw: 0 };
+
+        psr.set_irq_disabled(true);
+        psr.set_fiq_disabled(true);
+        psr.set_mode(CpuMode::Supervisor);
+        psr.set_state(CpuState::ARM);
+        println!("RAW: 0x{:08x}", psr.raw);
+
+        psr
+    }
+
+    pub fn get(&self) -> u32 {
+        self.raw
+    }
+
+    pub fn set(&mut self, psr: u32) {
+        self.raw = clear_reserved(psr);
+    }
+
+    pub fn state(&self) -> CpuState {
+        self.raw.bit(5).into()
+    }
+
+    pub fn set_state(&mut self, state: CpuState) {
+        self.raw.set_bit(5, state.into());
+    }
+
+    pub fn mode(&self) -> CpuMode {
+        CpuMode::from_u32(self.raw & 0xb11111).unwrap()
+    }
+
+    pub fn set_mode(&mut self, mode: CpuMode) {
+        self.raw |= mode as u32;
+    }
+
+    pub fn irq_disabled(&self) -> bool {
+        self.raw.bit(7)
+    }
+
+    pub fn set_irq_disabled(&mut self, disabled: bool) {
+        self.raw.set_bit(7, disabled);
+    }
+
+    pub fn fiq_disabled(&self) -> bool {
+        self.raw.bit(6)
+    }
+
+    pub fn set_fiq_disabled(&mut self, disabled: bool) {
+        self.raw.set_bit(6, disabled);
+    }
+
+    #[allow(non_snake_case)]
+    pub fn N(&self) -> bool {
+        self.raw.bit(31)
+    }
+
+    #[allow(non_snake_case)]
+    pub fn set_N(&mut self, flag: bool) {
+        self.raw.set_bit(31, flag);
+    }
+
+    #[allow(non_snake_case)]
+    pub fn Z(&self) -> bool {
+        self.raw.bit(30)
+    }
+
+    #[allow(non_snake_case)]
+    pub fn set_Z(&mut self, flag: bool) {
+        self.raw.set_bit(30, flag);
+    }
+
+    #[allow(non_snake_case)]
+    pub fn C(&self) -> bool {
+        self.raw.bit(29)
+    }
+
+    #[allow(non_snake_case)]
+    pub fn set_C(&mut self, flag: bool) {
+        self.raw.set_bit(29, flag);
+    }
+
+    #[allow(non_snake_case)]
+    pub fn V(&self) -> bool {
+        self.raw.bit(28)
+    }
+
+    #[allow(non_snake_case)]
+    pub fn set_V(&mut self, flag: bool) {
+        self.raw.set_bit(28, flag);
+    }
+}
+
+impl fmt::Display for RegPSR {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let disabled_string = |disabled: bool| -> ColoredString {
+            if disabled {
+                "disabled".bright_red()
+            } else {
+                "enabled".bright_green()
+            }
+        };
+        write!(
+            f,
+            "{{ mode: {mode}, state: {state}, irq: {irq}, fiq: {fiq}, condition_flags: (N={N} Z={Z} C={C} V={V}) }}",
+            mode = self.mode(),
+            state = self.state(),
+            irq = disabled_string(self.irq_disabled()),
+            fiq = disabled_string(self.irq_disabled()),
+            N = self.N() as u8,
+            Z = self.Z() as u8,
+            C = self.C() as u8,
+            V = self.V() as u8,
+            )
+    }
+}