finish base

README.md

@@ -4,8 +4,7 @@ A small RISC-V emulator written in Rust.
 
 ## Features
 
-- [ ] Base RV32I instruction set
-    - missing fence and pause
+- [x] Base RV32I instruction set
 - [x] M standard extension
 - [ ] A standard extension
 - [ ] F standard extension

src/elf.rs

@@ -4,7 +4,6 @@ pub struct Elf {
     pub content: Vec<u8>,
 }
 
-#[expect(dead_code)]
 #[derive(Debug)]
 pub struct Header {
     pub e_entry: u32,
@@ -19,7 +18,6 @@ pub struct Header {
     pub e_shstrndx: u16,
 }
 
-#[expect(dead_code)]
 #[derive(Debug)]
 pub struct Phdr {
     pub p_type: u32,

src/emu.rs

@@ -66,7 +66,6 @@ impl Memory {
 }
 
 #[derive(Debug)]
-#[expect(dead_code)]
 pub enum Error {
     Trap(&'static str),
     IllegalInstruction(InstCode, &'static str),
@@ -109,7 +108,6 @@ impl IndexMut<Reg> for Emulator {
 #[derive(Clone, Copy)]
 pub struct Reg(pub u32);
 
-#[expect(dead_code)]
 impl Reg {
     pub const RA: Reg = Reg(1);
     pub const SP: Reg = Reg(2);
@@ -307,6 +305,7 @@ impl Emulator {
             }
             Inst::Or { dest, src1, src2 } => self[dest] = self[src1] | self[src2],
             Inst::And { dest, src1, src2 } => self[dest] = self[src1] & self[src2],
+            Inst::Fence { fence: _ } => { /* dont care */ }
             Inst::Ecall => {
                 (self.ecall_handler)(&mut self.mem, &mut self.xreg)?;
             }

src/inst.rs

@@ -2,6 +2,7 @@ use crate::emu::{Error, Reg};
 use std::fmt::{Debug, Display};
 use std::ops::RangeInclusive;
 
+#[derive(Clone, Copy)]
 pub enum Inst {
     Lui { uimm: u32, dest: Reg },
     Auipc { uimm: u32, dest: Reg },
@@ -47,6 +48,8 @@ pub enum Inst {
     Or { dest: Reg, src1: Reg, src2: Reg },
     And { dest: Reg, src1: Reg, src2: Reg },
 
+    Fence { fence: Fence },
+
     Ecall,
     Ebreak,
 
@@ -61,6 +64,23 @@ pub enum Inst {
     Remu { dest: Reg, src1: Reg, src2: Reg },
 }
 
+#[derive(Clone, Copy)]
+pub struct Fence {
+    pub fm: u32,
+    pub pred: FenceSet,
+    pub succ: FenceSet,
+    pub dest: Reg,
+    pub src: Reg,
+}
+
+#[derive(Clone, Copy, PartialEq, Eq)]
+pub struct FenceSet {
+    pub device_input: bool,
+    pub device_output: bool,
+    pub memory_read: bool,
+    pub memory_write: bool,
+}
+
 impl Debug for Inst {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         Display::fmt(&self, f)
@@ -162,6 +182,28 @@ impl Display for Inst {
             Inst::Sra { dest, src1, src2 } => write!(f, "sra {dest}, {src1}, {src2}"),
             Inst::Or { dest, src1, src2 } => write!(f, "or {dest}, {src1}, {src2}"),
             Inst::And { dest, src1, src2 } => write!(f, "and {dest}, {src1}, {src2}"),
+            Inst::Fence { fence } => match fence.fm {
+                0b1000 => write!(f, "fence.TSO"),
+                0b0000
+                    if fence.pred
+                        == FenceSet {
+                            device_input: false,
+                            device_output: false,
+                            memory_read: false,
+                            memory_write: true,
+                        }
+                        && fence.succ
+                            == FenceSet {
+                                device_input: false,
+                                device_output: false,
+                                memory_read: false,
+                                memory_write: false,
+                            } =>
+                {
+                    write!(f, "pause")
+                }
+                _ => write!(f, "fence {},{}", fence.pred, fence.succ),
+            },
             Inst::Ecall => write!(f, "ecall"),
             Inst::Ebreak => write!(f, "ebreak"),
             Inst::Mul { dest, src1, src2 } => write!(f, "mul {dest}, {src1}, {src2}"),
@@ -176,6 +218,24 @@ impl Display for Inst {
     }
 }
 
+impl Display for FenceSet {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        if self.device_input {
+            write!(f, "i")?;
+        }
+        if self.device_output {
+            write!(f, "o")?;
+        }
+        if self.memory_read {
+            write!(f, "r")?;
+        }
+        if self.memory_write {
+            write!(f, "w")?;
+        }
+        Ok(())
+    }
+}
+
 fn sign_extend(value: u32, size: u32) -> u32 {
     assert!(size <= u32::BITS);
     let sign = value >> (size - 1);
@@ -439,6 +499,35 @@ impl Inst {
                     _ => return Err(Error::IllegalInstruction(code, "funct3/funct7")),
                 }
             }
+            // MISC-MEM
+            0b0001111 => {
+                let fm = code.extract(28..=31);
+                let pred = FenceSet {
+                    device_input: code.extract(27..=27) == 1,
+                    device_output: code.extract(26..=26) == 1,
+                    memory_read: code.extract(25..=25) == 1,
+                    memory_write: code.extract(24..=24) == 1,
+                };
+                let succ = FenceSet {
+                    device_input: code.extract(23..=23) == 1,
+                    device_output: code.extract(22..=22) == 1,
+                    memory_read: code.extract(21..=21) == 1,
+                    memory_write: code.extract(20..=20) == 1,
+                };
+
+                match code.funct3() {
+                    0b000 => Inst::Fence {
+                        fence: Fence {
+                            fm,
+                            pred,
+                            succ,
+                            dest: code.rd(),
+                            src: code.rs1(),
+                        },
+                    },
+                    _ => return Err(Error::IllegalInstruction(code, "funct3")),
+                }
+            }
             // SYSTEM
             0b1110011 => {
                 if code.0 == 0b11000000000000000001000001110011 {

src/lib.rs

@@ -0,0 +1,3 @@
+pub mod elf;
+pub mod emu;
+pub mod inst;

src/main.rs

@@ -1,9 +1,8 @@
-use emu::{Memory, Reg};
 use eyre::{OptionExt, bail, eyre};
-
-mod elf;
-mod emu;
-mod inst;
+use rustv32i::{
+    elf,
+    emu::{self, Memory, Reg},
+};
 
 // 2 MiB
 const MEMORY_SIZE: usize = 2 << 21;