From f5ecfd230ceb2fb8849d1da3d702859b31e3957b Mon Sep 17 00:00:00 2001
From: Giovanni Bajo <rasky@develer.com>
Date: Thu, 5 Sep 2024 23:28:30 +0200
Subject: [PATCH] n64: optimize RDRAM accesses by special casing them

---
 ares/n64/cpu/memory.cpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/ares/n64/cpu/memory.cpp b/ares/n64/cpu/memory.cpp
index fcd4a4165e..44fbc720ec 100644
--- a/ares/n64/cpu/memory.cpp
+++ b/ares/n64/cpu/memory.cpp
@@ -93,6 +93,11 @@ auto CPU::devirtualize(u64 vaddr, bool raiseAlignedError, bool raiseExceptions)
   if (raiseAlignedError && vaddrAlignedError<Size>(vaddr, Dir == Write)) {
     return PhysAccess{false};
   }
+  //fast path for RDRAM, which is by far the most accessed memory region
+  if (vaddr >= 0xffff'ffff'8000'0000ull && vaddr <= 0xffff'ffff'83ef'ffffull) {
+    if constexpr(Dir == Read)  return PhysAccess{true, true, (u32)vaddr & 0x3eff'ffff, vaddr};
+    if constexpr(Dir == Write) return PhysAccess{true, true, (u32)vaddr & 0x3eff'ffff, vaddr};
+  }
   switch(segment(vaddr)) {
   case Context::Segment::Unused:
     if(raiseExceptions) {