From 79644bfb2a1b5c5809abdef65cb43850e3875823 Mon Sep 17 00:00:00 2001
From: Stenzek <stenzek@gmail.com>
Date: Sun, 21 Jul 2024 13:33:54 +1000
Subject: [PATCH] CPU: Add Safe{Read,Write}MemoryBytes

---
 src/core/cpu_core.cpp | 48 +++++++++++++++++++++++++++++++++++++++++++
 src/core/cpu_core.h   |  2 ++
 2 files changed, 50 insertions(+)

diff --git a/src/core/cpu_core.cpp b/src/core/cpu_core.cpp
index 3b2ada372..9f439aa29 100644
--- a/src/core/cpu_core.cpp
+++ b/src/core/cpu_core.cpp
@@ -3076,6 +3076,54 @@ bool CPU::SafeWriteMemoryWord(VirtualMemoryAddress addr, u32 value)
   return SafeWriteMemoryHalfWord(addr, Truncate16(value)) && SafeWriteMemoryHalfWord(addr + 2, Truncate16(value >> 16));
 }
 
+bool CPU::SafeReadMemoryBytes(VirtualMemoryAddress addr, void* data, u32 length)
+{
+  using namespace Bus;
+
+  const u32 seg = (addr >> 29);
+  if ((seg != 0 && seg != 4 && seg != 5) || (((addr + length) & PHYSICAL_MEMORY_ADDRESS_MASK) >= RAM_MIRROR_END) ||
+      (((addr & g_ram_mask) + length) > g_ram_size))
+  {
+    u8* ptr = static_cast<u8*>(data);
+    u8* const ptr_end = ptr + length;
+    while (ptr != ptr_end)
+    {
+      if (!SafeReadMemoryByte(addr++, ptr++))
+        return false;
+    }
+
+    return true;
+  }
+
+  // Fast path: all in RAM, no wraparound.
+  std::memcpy(data, &g_ram[addr & g_ram_mask], length);
+  return true;
+}
+
+bool CPU::SafeWriteMemoryBytes(VirtualMemoryAddress addr, const void* data, u32 length)
+{
+  using namespace Bus;
+
+  const u32 seg = (addr >> 29);
+  if ((seg != 0 && seg != 4 && seg != 5) || (((addr + length) & PHYSICAL_MEMORY_ADDRESS_MASK) >= RAM_MIRROR_END) ||
+      (((addr & g_ram_mask) + length) > g_ram_size))
+  {
+    const u8* ptr = static_cast<const u8*>(data);
+    const u8* const ptr_end = ptr + length;
+    while (ptr != ptr_end)
+    {
+      if (!SafeWriteMemoryByte(addr++, *(ptr++)))
+        return false;
+    }
+
+    return true;
+  }
+
+  // Fast path: all in RAM, no wraparound.
+  std::memcpy(&g_ram[addr & g_ram_mask], data, length);
+  return true;
+}
+
 void* CPU::GetDirectReadMemoryPointer(VirtualMemoryAddress address, MemoryAccessSize size, TickCount* read_ticks)
 {
   using namespace Bus;
diff --git a/src/core/cpu_core.h b/src/core/cpu_core.h
index 57e060d55..b4d539f4b 100644
--- a/src/core/cpu_core.h
+++ b/src/core/cpu_core.h
@@ -183,9 +183,11 @@ bool SafeReadMemoryByte(VirtualMemoryAddress addr, u8* value);
 bool SafeReadMemoryHalfWord(VirtualMemoryAddress addr, u16* value);
 bool SafeReadMemoryWord(VirtualMemoryAddress addr, u32* value);
 bool SafeReadMemoryCString(VirtualMemoryAddress addr, std::string* value, u32 max_length = 1024);
+bool SafeReadMemoryBytes(VirtualMemoryAddress addr, void* data, u32 length);
 bool SafeWriteMemoryByte(VirtualMemoryAddress addr, u8 value);
 bool SafeWriteMemoryHalfWord(VirtualMemoryAddress addr, u16 value);
 bool SafeWriteMemoryWord(VirtualMemoryAddress addr, u32 value);
+bool SafeWriteMemoryBytes(VirtualMemoryAddress addr, const void* data, u32 length);
 
 // External IRQs
 void SetIRQRequest(bool state);