Noratrieb/rustv32i
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nora 2025-03-09 01:23:43 +01:00
parent ab8e4ebc13
commit 42c4d826f1
4 changed files with 135 additions and 10 deletions
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13
README.md Normal file
View file

@ -0,0 +1,13 @@
# rustv32i
A small RISC-V emulator written in Rust.
## Features
- [ ] Base RV32I instruction set
- missing fence and pause
- [x] M standard extension
- [ ] A standard extension
- [ ] F standard extension
- [ ] D standard extension
- [ ] C standard extension

71
src/emu.rs
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@ -183,6 +183,16 @@ enum Inst {
Ecall,
Ebreak,
// M
Mul { dest: Reg, src1: Reg, src2: Reg },
Mulh { dest: Reg, src1: Reg, src2: Reg },
Mulhsu { dest: Reg, src1: Reg, src2: Reg },
Mulhu { dest: Reg, src1: Reg, src2: Reg },
Div { dest: Reg, src1: Reg, src2: Reg },
Divu { dest: Reg, src1: Reg, src2: Reg },
Rem { dest: Reg, src1: Reg, src2: Reg },
Remu { dest: Reg, src1: Reg, src2: Reg },
}
impl Debug for Inst {
@ -288,6 +298,14 @@ impl Display for Inst {
Inst::And { dest, src1, src2 } => write!(f, "and {dest}, {src1}, {src2}"),
Inst::Ecall => write!(f, "ecall"),
Inst::Ebreak => write!(f, "ebreak"),
Inst::Mul { dest, src1, src2 } => write!(f, "mul {dest}, {src1}, {src2}"),
Inst::Mulh { dest, src1, src2 } => write!(f, "mulh {dest}, {src1}, {src2}"),
Inst::Mulhsu { dest, src1, src2 } => write!(f, "mulhsu {dest}, {src1}, {src2}"),
Inst::Mulhu { dest, src1, src2 } => write!(f, "mulhu {dest}, {src1}, {src2}"),
Inst::Div { dest, src1, src2 } => write!(f, "div {dest}, {src1}, {src2}"),
Inst::Divu { dest, src1, src2 } => write!(f, "divu {dest}, {src1}, {src2}"),
Inst::Rem { dest, src1, src2 } => write!(f, "rem {dest}, {src1}, {src2}"),
Inst::Remu { dest, src1, src2 } => write!(f, "remu {dest}, {src1}, {src2}"),
}
}
}
@ -542,6 +560,15 @@ impl Inst {
(0b101, 0b0100000) => Inst::Sra { dest, src1, src2 },
(0b110, 0b0000000) => Inst::Or { dest, src1, src2 },
(0b111, 0b0000000) => Inst::And { dest, src1, src2 },
(0b000, 0b0000001) => Inst::Mul { dest, src1, src2 },
(0b001, 0b0000001) => Inst::Mulh { dest, src1, src2 },
(0b010, 0b0000001) => Inst::Mulhsu { dest, src1, src2 },
(0b011, 0b0000001) => Inst::Mulhu { dest, src1, src2 },
(0b100, 0b0000001) => Inst::Div { dest, src1, src2 },
(0b101, 0b0000001) => Inst::Divu { dest, src1, src2 },
(0b110, 0b0000001) => Inst::Rem { dest, src1, src2 },
(0b111, 0b0000001) => Inst::Remu { dest, src1, src2 },
_ => return Err(Error::IllegalInstruction(code, "funct3/funct7")),
}
}
@ -751,6 +778,50 @@ impl Emulator {
(self.ecall_handler)(&mut self.mem, &mut self.xreg)?;
}
Inst::Ebreak => return Err(Error::Ebreak),
Inst::Mul { dest, src1, src2 } => {
self[dest] = ((self[src1] as i32).wrapping_mul(self[src2] as i32)) as u32;
}
Inst::Mulh { dest, src1, src2 } => {
let shifted = ((self[src1] as i64).wrapping_mul(self[src2] as i64) as i64) >> 32;
self[dest] = shifted as u32;
}
Inst::Mulhsu { .. } => todo!("mulhsu"),
Inst::Mulhu { dest, src1, src2 } => {
let shifted = ((self[src1] as u64).wrapping_mul(self[src2] as u64) as u64) >> 32;
self[dest] = shifted as u32;
}
Inst::Div { dest, src1, src2 } => {
if self[src2] == 0 {
self[dest] = u32::MAX;
} else if self[src2] == u32::MAX {
self[dest] = u32::MAX;
} else {
self[dest] = ((self[src1] as i32) / (self[src2] as i32)) as u32;
}
}
Inst::Divu { dest, src1, src2 } => {
if self[src2] == 0 {
self[dest] = 2_u32.pow(32) - 1;
} else {
self[dest] = self[src1] / self[src2];
}
}
Inst::Rem { dest, src1, src2 } => {
if self[src2] == 0 {
self[dest] = self[src1];
} else if self[src2] == u32::MAX {
self[dest] = 0;
} else {
self[dest] = ((self[src1] as i32) % (self[src2] as i32)) as u32;
}
}
Inst::Remu { dest, src1, src2 } => {
if self[src2] == 0 {
self[dest] = 2_u32.pow(32) - 1;
} else {
self[dest] = self[src1] % self[src2];
}
}
}
if !jumped {

2
test/Makefile
View file

@ -1,7 +1,7 @@
CC = clang -Wall -Wpedantic -target riscv32-unknown-linux-gnu -fuse-ld=lld -march=rv32i
CC_STATIC = $(CC) -static -nostdlib -nodefaultlibs
RUSTC = rustc --target riscv32i-unknown-none-elf
RUSTC = rustc --target riscv32im-unknown-none-elf
all: init init1

55
test/init1.rs
View file

@ -51,8 +51,23 @@ struct Stderr;
impl core::fmt::Write for Stderr {
fn write_str(&mut self, s: &str) -> core::fmt::Result {
let ret = write(2, s.as_bytes());
if ret < 0 { Err(core::fmt::Error) } else { Ok(()) }
if ret < 0 {
Err(core::fmt::Error)
} else {
Ok(())
}
}
}
macro_rules! eprintln {
($($tt:tt)*) => {
writeln!(Stderr, $($tt)*).unwrap();
};
}
macro_rules! eprint {
($($tt:tt)*) => {
write!(Stderr, $($tt)*).unwrap();
};
}
#[panic_handler]
@ -61,13 +76,39 @@ fn handle(info: &core::panic::PanicInfo<'_>) -> ! {
unsafe { core::arch::asm!("unimp", options(noreturn)) }
}
#[no_mangle]
fn _start() {
write(1, b"enter a number: ");
fn input() -> u64 {
eprint!("enter a number: ");
loop {
let mut buf = [0; 10];
let len = read(0, &mut buf);
let buf = &buf[..(len as usize)];
let n = str::from_utf8(buf).unwrap().trim().parse::<i32>().unwrap();
exit(n);
let n = str::from_utf8(buf).unwrap().trim();
match n.parse::<u64>() {
Ok(v) => return v,
Err(_) => {
eprint!("not a valid number, try again: ");
}
}
}
}
#[no_mangle]
fn _start() -> ! {
let random_number = 45;
loop {
let n = input();
if n == random_number {
eprintln!("correct!");
break;
} else if n < random_number {
eprintln!("random number is greater");
} else {
eprintln!("random number is smaller");
}
}
exit(0);
}