From 09d90643726d2a86952473e27b6e5d64543e41a0 Mon Sep 17 00:00:00 2001
From: taitep <taitep@taitep.se>
Date: Wed, 24 Dec 2025 13:56:41 +0100
Subject: EXCEPTION SYSTEM (initial version - may change later)

---
 src/instructions.rs | 88 +++++++++++++++++++++++++++++++----------------------
 1 file changed, 51 insertions(+), 37 deletions(-)

(limited to 'src/instructions.rs')

diff --git a/src/instructions.rs b/src/instructions.rs
index e4d5b03..482ea5d 100644
--- a/src/instructions.rs
+++ b/src/instructions.rs
@@ -7,67 +7,81 @@
 mod rvi;
 
 use crate::{
-    core::{Core, InstructionResult},
+    core::Core,
     decode::Instruction,
+    exceptions::ExceptionType::{self, IllegalInstruction},
 };
 
-pub(crate) fn find_and_exec(instr: Instruction, core: &mut Core) -> Option<InstructionResult> {
+pub(crate) fn find_and_exec(instr: Instruction, core: &mut Core) -> Result<(), ExceptionType> {
     match instr.opcode_noncompressed() {
         0b01100 => match (instr.funct7(), instr.funct3()) {
             // OP
-            (0b0000000, 0b000) => Some(rvi::add(core, instr)),
-            (0b0100000, 0b000) => Some(rvi::sub(core, instr)),
-            (0b0000000, 0b111) => Some(rvi::and(core, instr)),
-            (0b0000000, 0b110) => Some(rvi::or(core, instr)),
-            _ => None,
+            (0b0000000, 0b000) => rvi::add(core, instr),
+            (0b0100000, 0b000) => rvi::sub(core, instr),
+            (0b0000000, 0b111) => rvi::and(core, instr),
+            (0b0000000, 0b110) => rvi::or(core, instr),
+            _ => Err(IllegalInstruction),
         },
         0b00100 => match instr.funct3() {
             // OP_IMM
-            0b000 => Some(rvi::addi(core, instr)),
-            0b001 => (instr.funct6() == 0).then(|| rvi::slli(core, instr)),
+            0b000 => rvi::addi(core, instr),
+            0b001 => {
+                if instr.funct6() == 0 {
+                    rvi::slli(core, instr)
+                } else {
+                    Err(IllegalInstruction)
+                }
+            }
             0b101 => match instr.funct6() {
                 // immediate right-shift
-                0b000000 => Some(rvi::srli(core, instr)),
-                _ => None,
+                0b000000 => rvi::srli(core, instr),
+                _ => Err(IllegalInstruction),
             },
-            0b111 => Some(rvi::andi(core, instr)),
-            _ => None,
+            0b111 => rvi::andi(core, instr),
+            _ => Err(IllegalInstruction),
         },
         0b00110 => match instr.funct3() {
             // OP_IMM_32
-            0b000 => Some(rvi::addiw(core, instr)),
-            _ => None,
+            0b000 => rvi::addiw(core, instr),
+            _ => Err(IllegalInstruction),
         },
         0b01000 => match instr.funct3() {
             // STORE
-            0b000 => Some(rvi::sb(core, instr)),
-            0b001 => Some(rvi::sh(core, instr)),
-            0b010 => Some(rvi::sw(core, instr)),
-            0b011 => Some(rvi::sd(core, instr)),
-            _ => None,
+            0b000 => rvi::sb(core, instr),
+            0b001 => rvi::sh(core, instr),
+            0b010 => rvi::sw(core, instr),
+            0b011 => rvi::sd(core, instr),
+            _ => Err(IllegalInstruction),
         },
         0b00000 => match instr.funct3() {
             // LOAD
-            0b000 => Some(rvi::lb(core, instr)),
-            0b100 => Some(rvi::lbu(core, instr)),
-            0b001 => Some(rvi::lh(core, instr)),
-            0b010 => Some(rvi::lw(core, instr)),
-            0b011 => Some(rvi::ld(core, instr)),
-            _ => None,
+            0b000 => rvi::lb(core, instr),
+            0b100 => rvi::lbu(core, instr),
+            0b001 => rvi::lh(core, instr),
+            0b010 => rvi::lw(core, instr),
+            0b011 => rvi::ld(core, instr),
+            _ => Err(IllegalInstruction),
         },
         0b11000 => match instr.funct3() {
             // BRANCH
-            0b000 => Some(rvi::beq(core, instr)),
-            0b001 => Some(rvi::bne(core, instr)),
-            0b100 => Some(rvi::blt(core, instr)),
-            0b110 => Some(rvi::bltu(core, instr)),
-            0b111 => Some(rvi::bgeu(core, instr)),
-            _ => None,
+            0b000 => rvi::beq(core, instr),
+            0b001 => rvi::bne(core, instr),
+            0b100 => rvi::blt(core, instr),
+            0b110 => rvi::bltu(core, instr),
+            0b111 => rvi::bgeu(core, instr),
+            _ => Err(IllegalInstruction),
         },
-        0b01101 => Some(rvi::lui(core, instr)),
-        0b00101 => Some(rvi::auipc(core, instr)),
-        0b11011 => Some(rvi::jal(core, instr)),
-        0b11001 => (instr.funct3() == 0).then(|| rvi::jalr(core, instr)),
-        _ => None,
+        0b01101 => rvi::lui(core, instr),
+        0b00101 => rvi::auipc(core, instr),
+        0b11011 => rvi::jal(core, instr),
+        // 0b11001 => (instr.funct3() == 0).then(|| rvi::jalr(core, instr)),
+        0b11001 => {
+            if instr.funct3() == 0 {
+                rvi::jalr(core, instr)
+            } else {
+                Err(IllegalInstruction)
+            }
+        }
+        _ => Err(IllegalInstruction),
     }
 }
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