From 5f9648417cd3c1debaa9cf1f27fc61d05a253818 Mon Sep 17 00:00:00 2001
From: Pokechu22 <Pokechu022@gmail.com>
Date: Tue, 30 Aug 2022 12:42:45 -0700
Subject: [PATCH] Create Common/I2C

Currently this is a copy of the Wii Remote I2CBus, and is unused. That will change in later commits.
---
 Source/Core/Common/CMakeLists.txt |  2 +
 Source/Core/Common/I2C.cpp        | 53 ++++++++++++++++++++++
 Source/Core/Common/I2C.h          | 75 +++++++++++++++++++++++++++++++
 Source/Core/DolphinLib.props      |  2 +
 4 files changed, 132 insertions(+)
 create mode 100644 Source/Core/Common/I2C.cpp
 create mode 100644 Source/Core/Common/I2C.h

diff --git a/Source/Core/Common/CMakeLists.txt b/Source/Core/Common/CMakeLists.txt
index 81431e564c..048fffe2d1 100644
--- a/Source/Core/Common/CMakeLists.txt
+++ b/Source/Core/Common/CMakeLists.txt
@@ -79,6 +79,8 @@ add_library(common
   HostDisassembler.h
   HttpRequest.cpp
   HttpRequest.h
+  I2C.cpp
+  I2C.h
   Image.cpp
   Image.h
   IniFile.cpp
diff --git a/Source/Core/Common/I2C.cpp b/Source/Core/Common/I2C.cpp
new file mode 100644
index 0000000000..d44f98dffb
--- /dev/null
+++ b/Source/Core/Common/I2C.cpp
@@ -0,0 +1,53 @@
+// Copyright 2022 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "Common/I2C.h"
+
+#include <algorithm>
+
+namespace Common
+{
+void I2CBus::AddSlave(I2CSlave* slave)
+{
+  m_slaves.emplace_back(slave);
+}
+
+void I2CBus::RemoveSlave(I2CSlave* slave)
+{
+  m_slaves.erase(std::remove(m_slaves.begin(), m_slaves.end(), slave), m_slaves.end());
+}
+
+void I2CBus::Reset()
+{
+  m_slaves.clear();
+}
+
+int I2CBus::BusRead(u8 slave_addr, u8 addr, int count, u8* data_out)
+{
+  for (auto& slave : m_slaves)
+  {
+    auto const bytes_read = slave->BusRead(slave_addr, addr, count, data_out);
+
+    // A slave responded, we are done.
+    if (bytes_read)
+      return bytes_read;
+  }
+
+  return 0;
+}
+
+int I2CBus::BusWrite(u8 slave_addr, u8 addr, int count, const u8* data_in)
+{
+  for (auto& slave : m_slaves)
+  {
+    auto const bytes_written = slave->BusWrite(slave_addr, addr, count, data_in);
+
+    // A slave responded, we are done.
+    if (bytes_written)
+      return bytes_written;
+  }
+
+  return 0;
+}
+
+};  // namespace Common
diff --git a/Source/Core/Common/I2C.h b/Source/Core/Common/I2C.h
new file mode 100644
index 0000000000..1ea1c8198d
--- /dev/null
+++ b/Source/Core/Common/I2C.h
@@ -0,0 +1,75 @@
+// Copyright 2022 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <algorithm>
+#include <vector>
+
+#include "Common/CommonTypes.h"
+
+namespace Common
+{
+class I2CBus;
+
+class I2CSlave
+{
+  friend I2CBus;
+
+protected:
+  virtual ~I2CSlave() = default;
+
+  virtual int BusRead(u8 slave_addr, u8 addr, int count, u8* data_out) = 0;
+  virtual int BusWrite(u8 slave_addr, u8 addr, int count, const u8* data_in) = 0;
+
+  template <typename T>
+  static int RawRead(T* reg_data, u8 addr, int count, u8* data_out)
+  {
+    static_assert(std::is_standard_layout_v<T> && std::is_trivially_copyable_v<T>);
+    static_assert(0x100 == sizeof(T));
+
+    // TODO: addr wraps around after 0xff
+
+    u8* src = reinterpret_cast<u8*>(reg_data) + addr;
+    count = std::min(count, int(reinterpret_cast<u8*>(reg_data + 1) - src));
+
+    std::copy_n(src, count, data_out);
+
+    return count;
+  }
+
+  template <typename T>
+  static int RawWrite(T* reg_data, u8 addr, int count, const u8* data_in)
+  {
+    static_assert(std::is_standard_layout_v<T> && std::is_trivially_copyable_v<T>);
+    static_assert(0x100 == sizeof(T));
+
+    // TODO: addr wraps around after 0xff
+
+    u8* dst = reinterpret_cast<u8*>(reg_data) + addr;
+    count = std::min(count, int(reinterpret_cast<u8*>(reg_data + 1) - dst));
+
+    std::copy_n(data_in, count, dst);
+
+    return count;
+  }
+};
+
+class I2CBus
+{
+public:
+  void AddSlave(I2CSlave* slave);
+  void RemoveSlave(I2CSlave* slave);
+
+  void Reset();
+
+  // TODO: change int to u16 or something
+  int BusRead(u8 slave_addr, u8 addr, int count, u8* data_out);
+  int BusWrite(u8 slave_addr, u8 addr, int count, const u8* data_in);
+
+private:
+  // Pointers are unowned:
+  std::vector<I2CSlave*> m_slaves;
+};
+
+}  // namespace Common
diff --git a/Source/Core/DolphinLib.props b/Source/Core/DolphinLib.props
index a61f0d822a..b6967694ee 100644
--- a/Source/Core/DolphinLib.props
+++ b/Source/Core/DolphinLib.props
@@ -120,6 +120,7 @@
     <ClInclude Include="Common\HostDisassembler.h" />
     <ClInclude Include="Common\HRWrap.h" />
     <ClInclude Include="Common\HttpRequest.h" />
+    <ClInclude Include="Common\I2C.h" />
     <ClInclude Include="Common\Image.h" />
     <ClInclude Include="Common\IniFile.h" />
     <ClInclude Include="Common\Inline.h" />
@@ -812,6 +813,7 @@
     <ClCompile Include="Common\HostDisassembler.cpp" />
     <ClCompile Include="Common\HRWrap.cpp" />
     <ClCompile Include="Common\HttpRequest.cpp" />
+    <ClCompile Include="Common\I2C.cpp" />
     <ClCompile Include="Common\Image.cpp" />
     <ClCompile Include="Common\IniFile.cpp" />
     <ClCompile Include="Common\IOFile.cpp" />