libretro: Cheat support

README.md

@@ -13,6 +13,7 @@ A "BIOS" ROM image is required to to start the emulator and to play games. You c
 
 ## Latest News
 
+- 2020/09/25: Cheat support added for libretro core.
 - 2020/09/23: Game covers added to Qt frontend (see [Adding Game Covers](https://github.com/stenzek/duckstation/wiki/Adding-Game-Covers)).
 - 2020/09/19: Memory card importer/editor added to Qt frontend.
 - 2020/09/13: Support for chaining post processing shaders added.

src/core/cheats.cpp

@@ -196,47 +196,53 @@ bool CheatList::LoadFromLibretroFile(const char* filename)
     CheatCode cc;
     cc.description = *desc;
     cc.enabled = StringUtil::FromChars<bool>(*enable).value_or(false);
+    if (ParseLibretroCheat(&cc, code->c_str()))
+      m_codes.push_back(std::move(cc));
+  }
+
+  Log_InfoPrintf("Loaded %zu cheats from '%s' (libretro format)", m_codes.size(), filename);
+  return !m_codes.empty();
+}
 
-    const char* current_ptr = code->c_str();
-    while (current_ptr)
+bool CheatList::ParseLibretroCheat(CheatCode* cc, const char* line)
+{
+  const char* current_ptr = line;
+  while (current_ptr)
+  {
+    char* end_ptr;
+    CheatCode::Instruction inst;
+    inst.first = static_cast<u32>(std::strtoul(current_ptr, &end_ptr, 16));
+    current_ptr = end_ptr;
+    if (end_ptr)
     {
-      char* end_ptr;
-      CheatCode::Instruction inst;
-      inst.first = static_cast<u32>(std::strtoul(current_ptr, &end_ptr, 16));
-      current_ptr = end_ptr;
+      if (*end_ptr != ' ')
+      {
+        Log_WarningPrintf("Malformed code '%s'", line);
+        break;
+      }
+
+      end_ptr++;
+      inst.second = static_cast<u32>(std::strtoul(current_ptr, &end_ptr, 16));
+      if (end_ptr && *end_ptr == '\0')
+        end_ptr = nullptr;
+
       if (end_ptr)
       {
-        if (*end_ptr != ' ')
+        if (*end_ptr != '+')
         {
-          Log_WarningPrintf("Malformed code '%s'", code->c_str());
+          Log_WarningPrintf("Malformed code '%s'", line);
           break;
         }
 
         end_ptr++;
-        inst.second = static_cast<u32>(std::strtoul(current_ptr, &end_ptr, 16));
-        current_ptr = end_ptr;
-
-        if (end_ptr)
-        {
-          if (*end_ptr != '+')
-          {
-            Log_WarningPrintf("Malformed code '%s'", code->c_str());
-            break;
-          }
-
-          end_ptr++;
-          current_ptr = end_ptr;
-        }
-
-        cc.instructions.push_back(inst);
       }
-    }
 
-    m_codes.push_back(std::move(cc));
+      current_ptr = end_ptr;
+      cc->instructions.push_back(inst);
+    }
   }
 
-  Log_InfoPrintf("Loaded %zu cheats from '%s' (libretro format)", m_codes.size(), filename);
-  return !m_codes.empty();
+  return !cc->instructions.empty();
 }
 
 void CheatList::Apply()
@@ -253,6 +259,20 @@ void CheatList::AddCode(CheatCode cc)
   m_codes.push_back(std::move(cc));
 }
 
+void CheatList::SetCode(u32 index, CheatCode cc)
+{
+  if (index > m_codes.size())
+    return;
+
+  if (index == m_codes.size())
+  {
+    m_codes.push_back(std::move(cc));
+    return;
+  }
+
+  m_codes[index] = std::move(cc);
+}
+
 void CheatList::RemoveCode(u32 i)
 {
   m_codes.erase(m_codes.begin() + i);

src/core/cheats.h

@@ -71,6 +71,7 @@ public:
   ALWAYS_INLINE bool IsCodeEnabled(u32 index) const { return m_codes[index].enabled; }
 
   void AddCode(CheatCode cc);
+  void SetCode(u32 index, CheatCode cc);
   void RemoveCode(u32 i);
 
   u32 GetEnabledCodeCount() const;
@@ -79,6 +80,7 @@ public:
   void SetCodeEnabled(u32 index, bool state);
 
   static std::optional<Format> DetectFileFormat(const char* filename);
+  static bool ParseLibretroCheat(CheatCode* cc, const char* line);
 
   bool LoadFromFile(const char* filename, Format format);
   bool LoadFromPCSXRFile(const char* filename);

src/duckstation-libretro/libretro_host_interface.cpp

@@ -6,6 +6,7 @@
 #include "common/string_util.h"
 #include "core/analog_controller.h"
 #include "core/bus.h"
+#include "core/cheats.h"
 #include "core/digital_controller.h"
 #include "core/gpu.h"
 #include "core/system.h"
@@ -369,6 +370,29 @@ size_t LibretroHostInterface::retro_get_memory_size(unsigned id)
   }
 }
 
+void LibretroHostInterface::retro_cheat_reset()
+{
+  System::SetCheatList(nullptr);
+}
+
+void LibretroHostInterface::retro_cheat_set(unsigned index, bool enabled, const char* code)
+{
+  CheatList* cl = System::GetCheatList();
+  if (!cl)
+  {
+    System::SetCheatList(std::make_unique<CheatList>());
+    cl = System::GetCheatList();
+  }
+
+  CheatCode cc;
+  cc.description = StringUtil::StdStringFromFormat("Cheat%u", index);
+  cc.enabled = true;
+  if (!CheatList::ParseLibretroCheat(&cc, code))
+    Log_ErrorPrintf("Failed to parse cheat %u '%s'", index, code);
+
+  cl->SetCode(index, std::move(cc));
+}
+
 bool LibretroHostInterface::AcquireHostDisplay()
 {
   // start in software mode, switch to hardware later

src/duckstation-libretro/libretro_host_interface.h

@@ -40,6 +40,8 @@ public:
   bool retro_unserialize(const void* data, size_t size);
   void* retro_get_memory_data(unsigned id);
   size_t retro_get_memory_size(unsigned id);
+  void retro_cheat_reset();
+  void retro_cheat_set(unsigned index, bool enabled, const char* code);
 
 protected:
   bool AcquireHostDisplay() override;

src/duckstation-libretro/main.cpp

@@ -79,12 +79,14 @@ RETRO_API bool retro_unserialize(const void* data, size_t size)
 
 RETRO_API void retro_cheat_reset(void)
 {
-  Log_ErrorPrintf("retro_cheat_reset()");
+  Log_InfoPrint("retro_cheat_reset()");
+  g_libretro_host_interface.retro_cheat_reset();
 }
 
 RETRO_API void retro_cheat_set(unsigned index, bool enabled, const char* code)
 {
-  Log_ErrorPrintf("retro_cheat_set(%u, %u, %s)", index, enabled, code);
+  Log_InfoPrintf("retro_cheat_set(%u, %u, %s)", index, enabled, code);
+  g_libretro_host_interface.retro_cheat_set(index, enabled, code);
 }
 
 RETRO_API bool retro_load_game(const struct retro_game_info* game)