Improve exception dumps and general debug info, make the emulator capable of running the riscv ISA tests, and perform some general fixes i found while making it pass the tests for RV64I

run-riscv-tests.sh

@@ -0,0 +1,12 @@
+#!/bin/bash
+
+for f in $(cat torun.txt); do
+    result=$(cargo run $f 2>&1 | tail -n 1 | awk '{print $NF}')
+    if [[ $result != 0 ]]; then
+        testnum=$(( result >> 1 ))
+        echo $f: test $testnum failed
+        exit 1
+    fi
+done
+
+echo all tests passed

src/core.rs

@@ -164,7 +164,7 @@ impl Core {
         let instr = Instruction(instr);
 
         if let Err(e) = find_and_exec(instr, self) {
-            eprintln!("instr: {:08x}", instr.0);
+            dbg!(instr);
             return Err(e);
         }
 
@@ -174,6 +174,7 @@ impl Core {
     fn throw_exception(&mut self, exception: Exception) {
         eprintln!("Exception: {exception:?}");
         dbg!(self.pc, self.x_regs);
+        dbg!(self.x_regs[10]);
     }
 
     pub fn reset(&mut self, pc: u64) {

src/decode.rs

@@ -6,9 +6,15 @@
 
 const MASK_REGISTER: u32 = 0x1f;
 
-#[derive(Debug, Clone, Copy)]
+#[derive(Clone, Copy)]
 pub struct Instruction(pub u32);
 
+impl std::fmt::Debug for Instruction {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_fmt(format_args!("{:08x}", self.0))
+    }
+}
+
 #[allow(dead_code)]
 impl Instruction {
     #[inline]

src/instructions.rs

@@ -131,6 +131,7 @@ pub(crate) fn find_and_exec(instr: Instruction, core: &mut Core) -> Result<(), E
                 // FENCE is just implemented as a SeqCst fence always here
                 // I dont yet care about the potential performance issue this may bring
                 std::sync::atomic::fence(std::sync::atomic::Ordering::SeqCst);
+                core.advance_pc();
                 Ok(())
             }
             _ => illegal(instr),
@@ -142,7 +143,15 @@ pub(crate) fn find_and_exec(instr: Instruction, core: &mut Core) -> Result<(), E
                 Err(ExceptionType::EnvironmentCallFromMMode.with_no_value())
             }
             (0b000, 0b000000000001, 0, 0) => Err(ExceptionType::Breakpoint.with_no_value()),
-            _ => illegal(instr),
+            _ => {
+                // Temporarily allowing unrecognized instructions here to be able to run
+                // the official ISA tests, which perform CSR operations but work just fine
+                // without them
+                eprintln!("Unrecognized instruction within SYSTEM opcode");
+                dbg!(instr);
+                core.advance_pc();
+                Ok(())
+            }
         },
         _ => illegal(instr),
     }

src/instructions/rvi.rs

@@ -32,7 +32,7 @@ instr_op!(srl, srli, |x, shamt| x >> (shamt & 0b111111));
 instr_op!(
     srlw,
     srliw,
-    |x, shamt| (x >> (shamt & 0b11111)) as i32 as i64 as u64
+    |x, shamt| (x as u32 >> (shamt & 0b11111)) as i32 as i64 as u64
 );
 instr_op!(sra, srai, |x, shamt| (x as i64 >> (shamt & 0b111111))
     as u64);
@@ -64,8 +64,9 @@ pub fn jal(core: &mut Core, instr: Instruction) -> Result<(), Exception> {
 }
 
 pub fn jalr(core: &mut Core, instr: Instruction) -> Result<(), Exception> {
+    let target = core.reg_read(instr.rs1()).wrapping_add(instr.imm_i()) & !1;
     core.reg_write(instr.rd(), core.pc.wrapping_add(4));
-    core.pc = core.reg_read(instr.rs1()).wrapping_add(instr.imm_i());
+    core.pc = target;
     Ok(())
 }
 

src/mem.rs

@@ -263,8 +263,8 @@ impl Ram {
         if !addr.is_multiple_of(8) {
             let high_word_addr = addr.wrapping_add(4);
 
-            let low_word = self.read_byte(addr)?;
+            let low_word = self.read_word(addr)?;
-            let high_word = self.read_byte(high_word_addr)?;
+            let high_word = self.read_word(high_word_addr)?;
 
             return Ok((low_word as u64) | (high_word as u64) << 32);
         }