From f9541157b62ec44deff0b906757c223ca0220102 Mon Sep 17 00:00:00 2001
From: Steven Le Rouzic <steven.lerouzic@gmail.com>
Date: Sun, 12 May 2024 17:02:54 +0200
Subject: Division

---
 emulator/hart.c      | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++--
 emulator/hart_test.c | 30 ++++++++++++++++++++++++
 2 files changed, 93 insertions(+), 2 deletions(-)

(limited to 'emulator')

diff --git a/emulator/hart.c b/emulator/hart.c
index 101d77f..297148b 100644
--- a/emulator/hart.c
+++ b/emulator/hart.c
@@ -220,7 +220,7 @@ static void execute_op(Hart* hart, uint32_t instruction)
     }
     else if (bank == 1)
     {
-        if ((inst.funct3 & 0x8) == 0)
+        if ((inst.funct3 & 0x4) == 0)
         {
             uint64_t a = hart->regs[inst.rs1];
             uint64_t b = hart->regs[inst.rs2];
@@ -241,7 +241,68 @@ static void execute_op(Hart* hart, uint32_t instruction)
         }
         else
         {
-            assert(!"Unhandled M OP");
+            uint32_t a = hart->regs[inst.rs1];
+            uint32_t b = hart->regs[inst.rs2];
+
+            switch (inst.funct3 & 0x3)
+            {
+                case 0: // DIV
+                {
+                    if (b == 0)
+                    {
+                        hart->regs[inst.rd] = 0xFFFFFFFF;
+                    }
+                    else if (a == 0x80000000 && b == 0xFFFFFFFF)
+                    {
+                        hart->regs[inst.rd] = 0x80000000;
+                    }
+                    else
+                    {
+                        hart->regs[inst.rd] = (uint32_t)((int32_t)a / (int32_t)b);
+                    }
+                    break;
+                }
+                case 1: // DIVU
+                {
+                    if (b == 0)
+                    {
+                        hart->regs[inst.rd] = 0xFFFFFFFF;
+                    }
+                    else
+                    {
+                        hart->regs[inst.rd] = a / b;
+                    }
+                    break;
+                }
+                case 2: // REM
+                {
+                    if (b == 0)
+                    {
+                        hart->regs[inst.rd] = a;
+                    }
+                    else if (a == 0x80000000 && b == 0xFFFFFFFF)
+                    {
+                        hart->regs[inst.rd] = 0;
+                    }
+                    else
+                    {
+                        hart->regs[inst.rd] = (uint32_t)((int32_t)a % (int32_t)b);
+                    }
+                    break;
+                }
+                case 3: // REMU
+                {
+                    if (b == 0)
+                    {
+                        hart->regs[inst.rd] = a;
+                    }
+                    else
+                    {
+                        hart->regs[inst.rd] = a % b;
+                    }
+                    break;
+                }
+            }
         }
     }
     else
diff --git a/emulator/hart_test.c b/emulator/hart_test.c
index 1611804..0dea92a 100644
--- a/emulator/hart_test.c
+++ b/emulator/hart_test.c
@@ -263,6 +263,36 @@ static void test_m()
 
     execute(&hart, 0x022091b3); // mulh x3, x1, x2
     assert(hart.regs[3] == 0x00000000);
+
+    hart.regs[1] = (uint32_t)-63;
+    hart.regs[2] = 4;
+    
+    execute(&hart, 0x0220c1b3); // div x3, x1, x2
+    assert(hart.regs[3] == (uint32_t)-15);
+    
+    execute(&hart, 0x0220d1b3); // divu x3, x1, x2
+    assert(hart.regs[3] == 0x3FFFFFF0);
+    
+    execute(&hart, 0x0220e1b3); // rem x3, x1, x2
+    assert(hart.regs[3] == (uint32_t)-3);
+    
+    execute(&hart, 0x0220f1b3); // remu x3, x1, x2
+    assert(hart.regs[3] == 1);
+
+    hart.regs[1] = 30;
+    hart.regs[2] = 0;
+    
+    execute(&hart, 0x0220c1b3); // div x3, x1, x2
+    assert(hart.regs[3] == 0xFFFFFFFF);
+    
+    execute(&hart, 0x0220d1b3); // divu x3, x1, x2
+    assert(hart.regs[3] == 0xFFFFFFFF);
+    
+    execute(&hart, 0x0220e1b3); // rem x3, x1, x2
+    assert(hart.regs[3] == 30);
+    
+    execute(&hart, 0x0220f1b3); // remu x3, x1, x2
+    assert(hart.regs[3] == 30);
 }
 
 int main(int argc, char* argv[])
-- 
cgit