SDL: Try matching gamepad mappings with CRC first

From d819106c65f23b666ff281c01c168d734a88a17b Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Tue, 14 Oct 2025 09:48:03 -0700
Subject: [PATCH] Try matching gamepad mappings with CRC first

Fixes https://github.com/libsdl-org/SDL/issues/13874
---
 src/joystick/SDL_gamepad.c     |  16 ++++-
 test/testautomation_joystick.c | 114 ++++++++++++++++++++++++++++-----
 2 files changed, 112 insertions(+), 18 deletions(-)

diff --git a/src/joystick/SDL_gamepad.c b/src/joystick/SDL_gamepad.c
index c4b7ade14bc87..d2e2ca3274db7 100644
--- a/src/joystick/SDL_gamepad.c
+++ b/src/joystick/SDL_gamepad.c
@@ -1372,7 +1372,8 @@ static GamepadMapping_t *SDL_PrivateGetGamepadMappingForGUID(SDL_GUID guid, bool
 {
     GamepadMapping_t *mapping;
 
-    mapping = SDL_PrivateMatchGamepadMappingForGUID(guid, true, adding_mapping);
+    // Try first with an exact match on version and CRC
+    mapping = SDL_PrivateMatchGamepadMappingForGUID(guid, true, true);
     if (mapping) {
         return mapping;
     }
@@ -1382,10 +1383,19 @@ static GamepadMapping_t *SDL_PrivateGetGamepadMappingForGUID(SDL_GUID guid, bool
         return NULL;
     }
 
-    // Try harder to get the best match, or create a mapping
+    // Try without CRC match
+    mapping = SDL_PrivateMatchGamepadMappingForGUID(guid, true, false);
+    if (mapping) {
+        return mapping;
+    }
 
+    // Try without version match
     if (SDL_JoystickGUIDUsesVersion(guid)) {
-        // Try again, ignoring the version
+        mapping = SDL_PrivateMatchGamepadMappingForGUID(guid, false, true);
+        if (mapping) {
+            return mapping;
+        }
+
         mapping = SDL_PrivateMatchGamepadMappingForGUID(guid, false, false);
         if (mapping) {
             return mapping;
diff --git a/test/testautomation_joystick.c b/test/testautomation_joystick.c
index bce6c7f2d1ba0..13ad53c1dd1af 100644
--- a/test/testautomation_joystick.c
+++ b/test/testautomation_joystick.c
@@ -9,6 +9,24 @@
 
 /* ================= Test Case Implementation ================== */
 
+/* Fixture */
+
+/* Create a 32-bit writable surface for blitting tests */
+static void SDLCALL joystickSetUp(void **arg)
+{
+    SDL_InitSubSystem(SDL_INIT_GAMEPAD);
+
+    SDL_SetHint(SDL_HINT_JOYSTICK_ALLOW_BACKGROUND_EVENTS, "1");
+}
+
+static void SDLCALL joystickTearDown(void *arg)
+{
+    SDL_ResetHint(SDL_HINT_JOYSTICK_ALLOW_BACKGROUND_EVENTS);
+
+    SDL_QuitSubSystem(SDL_INIT_GAMEPAD);
+}
+
+
 /* Test case functions */
 
 /**
@@ -16,23 +34,19 @@
  *
  * \sa SDL_AttachVirtualJoystick
  */
-static int SDLCALL TestVirtualJoystick(void *arg)
+static int SDLCALL joystick_testVirtual(void *arg)
 {
     SDL_VirtualJoystickDesc desc;
     SDL_Joystick *joystick = NULL;
     SDL_Gamepad *gamepad = NULL;
     SDL_JoystickID device_id;
 
-    SDLTest_AssertCheck(SDL_InitSubSystem(SDL_INIT_GAMEPAD), "SDL_InitSubSystem(SDL_INIT_GAMEPAD)");
-
-    SDL_SetHint(SDL_HINT_JOYSTICK_ALLOW_BACKGROUND_EVENTS, "1");
-
     SDL_INIT_INTERFACE(&desc);
     desc.type = SDL_JOYSTICK_TYPE_GAMEPAD;
     desc.naxes = SDL_GAMEPAD_AXIS_COUNT;
     desc.nbuttons = SDL_GAMEPAD_BUTTON_COUNT;
     desc.vendor_id = USB_VENDOR_NVIDIA;
-    desc.product_id = USB_PRODUCT_NVIDIA_SHIELD_CONTROLLER_V104;
+    desc.product_id = USB_PRODUCT_NVIDIA_SHIELD_CONTROLLER_V103;
     desc.name = "Virtual NVIDIA SHIELD Controller";
     device_id = SDL_AttachVirtualJoystick(&desc);
     SDLTest_AssertCheck(device_id > 0, "SDL_AttachVirtualJoystick() -> %" SDL_PRIs32 " (expected > 0)", device_id);
@@ -111,7 +125,7 @@ static int SDLCALL TestVirtualJoystick(void *arg)
                 }
 
                 /* Set an explicit mapping with a different name */
-                SDL_SetGamepadMapping(SDL_GetJoystickID(joystick), "ff0013db5669727475616c2043007601,Virtual Gamepad,a:b0,b:b1,x:b2,y:b3,back:b4,guide:b5,start:b6,leftstick:b7,rightstick:b8,leftshoulder:b9,rightshoulder:b10,dpup:b11,dpdown:b12,dpleft:b13,dpright:b14,misc1:b15,paddle1:b16,paddle2:b17,paddle3:b18,paddle4:b19,leftx:a0,lefty:a1,rightx:a2,righty:a3,lefttrigger:a4,righttrigger:a5,");
+                SDL_SetGamepadMapping(SDL_GetJoystickID(joystick), "ff008316550900001072000000007601,Virtual Gamepad,a:b0,b:b1,x:b2,y:b3,back:b4,guide:b5,start:b6,leftstick:b7,rightstick:b8,leftshoulder:b9,rightshoulder:b10,dpup:b11,dpdown:b12,dpleft:b13,dpright:b14,misc1:b15,paddle1:b16,paddle2:b17,paddle3:b18,paddle4:b19,leftx:a0,lefty:a1,rightx:a2,righty:a3,lefttrigger:a4,righttrigger:a5,");
                 {
                     const char *name = SDL_GetGamepadName(gamepad);
                     SDLTest_AssertCheck(name && SDL_strcmp(name, "Virtual Gamepad") == 0, "SDL_GetGamepadName() ->\"%s\" (expected \"%s\")", name, "Virtual Gamepad");
@@ -133,7 +147,7 @@ static int SDLCALL TestVirtualJoystick(void *arg)
                 SDLTest_AssertCheck(SDL_GetGamepadButton(gamepad, SDL_GAMEPAD_BUTTON_SOUTH) == false, "SDL_GetGamepadButton(SDL_GAMEPAD_BUTTON_SOUTH) == false");
 
                 /* Set an explicit mapping with legacy GameCube style buttons */
-                SDL_SetGamepadMapping(SDL_GetJoystickID(joystick), "ff0013db5669727475616c2043007601,Virtual Nintendo GameCube,a:b0,b:b1,x:b2,y:b3,back:b4,guide:b5,start:b6,leftstick:b7,rightstick:b8,leftshoulder:b9,rightshoulder:b10,dpup:b11,dpdown:b12,dpleft:b13,dpright:b14,misc1:b15,paddle1:b16,paddle2:b17,paddle3:b18,paddle4:b19,leftx:a0,lefty:a1,rightx:a2,righty:a3,lefttrigger:a4,righttrigger:a5,hint:SDL_GAMECONTROLLER_USE_GAMECUBE_LABELS:=1,");
+                SDL_SetGamepadMapping(SDL_GetJoystickID(joystick), "ff008316550900001072000000007601,Virtual Nintendo GameCube,a:b0,b:b1,x:b2,y:b3,back:b4,guide:b5,start:b6,leftstick:b7,rightstick:b8,leftshoulder:b9,rightshoulder:b10,dpup:b11,dpdown:b12,dpleft:b13,dpright:b14,misc1:b15,paddle1:b16,paddle2:b17,paddle3:b18,paddle4:b19,leftx:a0,lefty:a1,rightx:a2,righty:a3,lefttrigger:a4,righttrigger:a5,hint:SDL_GAMECONTROLLER_USE_GAMECUBE_LABELS:=1,");
                 {
                     const char *name = SDL_GetGamepadName(gamepad);
                     SDLTest_AssertCheck(name && SDL_strcmp(name, "Virtual Nintendo GameCube") == 0, "SDL_GetGamepadName() -> \"%s\" (expected \"%s\")", name, "Virtual Nintendo GameCube");
@@ -150,7 +164,7 @@ static int SDLCALL TestVirtualJoystick(void *arg)
                 SDLTest_AssertCheck(SDL_GetGamepadButton(gamepad, SDL_GAMEPAD_BUTTON_WEST) == false, "SDL_GetGamepadButton(SDL_GAMEPAD_BUTTON_WEST) == false");
 
                 /* Set an explicit mapping with legacy Nintendo style buttons */
-                SDL_SetGamepadMapping(SDL_GetJoystickID(joystick), "ff0013db5669727475616c2043007601,Virtual Nintendo Gamepad,a:b1,b:b0,x:b3,y:b2,back:b4,guide:b5,start:b6,leftstick:b7,rightstick:b8,leftshoulder:b9,rightshoulder:b10,dpup:b11,dpdown:b12,dpleft:b13,dpright:b14,misc1:b15,paddle1:b16,paddle2:b17,paddle3:b18,paddle4:b19,leftx:a0,lefty:a1,rightx:a2,righty:a3,lefttrigger:a4,righttrigger:a5,hint:SDL_GAMECONTROLLER_USE_BUTTON_LABELS:=1,");
+                SDL_SetGamepadMapping(SDL_GetJoystickID(joystick), "ff008316550900001072000000007601,Virtual Nintendo Gamepad,a:b1,b:b0,x:b3,y:b2,back:b4,guide:b5,start:b6,leftstick:b7,rightstick:b8,leftshoulder:b9,rightshoulder:b10,dpup:b11,dpdown:b12,dpleft:b13,dpright:b14,misc1:b15,paddle1:b16,paddle2:b17,paddle3:b18,paddle4:b19,leftx:a0,lefty:a1,rightx:a2,righty:a3,lefttrigger:a4,righttrigger:a5,hint:SDL_GAMECONTROLLER_USE_BUTTON_LABELS:=1,");
                 {
                     const char *name = SDL_GetGamepadName(gamepad);
                     SDLTest_AssertCheck(name && SDL_strcmp(name, "Virtual Nintendo Gamepad") == 0, "SDL_GetGamepadName() -> \"%s\" (expected \"%s\")", name, "Virtual Nintendo Gamepad");
@@ -167,7 +181,7 @@ static int SDLCALL TestVirtualJoystick(void *arg)
                 SDLTest_AssertCheck(SDL_GetGamepadButton(gamepad, SDL_GAMEPAD_BUTTON_SOUTH) == false, "SDL_GetGamepadButton(SDL_GAMEPAD_BUTTON_SOUTH) == false");
 
                 /* Set an explicit mapping with PS4 style buttons */
-                SDL_SetGamepadMapping(SDL_GetJoystickID(joystick), "ff0013db5669727475616c2043007601,Virtual PS4 Gamepad,type:ps4,a:b0,b:b1,x:b2,y:b3,back:b4,guide:b5,start:b6,leftstick:b7,rightstick:b8,leftshoulder:b9,rightshoulder:b10,dpup:b11,dpdown:b12,dpleft:b13,dpright:b14,misc1:b15,paddle1:b16,paddle2:b17,paddle3:b18,paddle4:b19,leftx:a0,lefty:a1,rightx:a2,righty:a3,lefttrigger:a4,righttrigger:a5,");
+                SDL_SetGamepadMapping(SDL_GetJoystickID(joystick), "ff008316550900001072000000007601,Virtual PS4 Gamepad,type:ps4,a:b0,b:b1,x:b2,y:b3,back:b4,guide:b5,start:b6,leftstick:b7,rightstick:b8,leftshoulder:b9,rightshoulder:b10,dpup:b11,dpdown:b12,dpleft:b13,dpright:b14,misc1:b15,paddle1:b16,paddle2:b17,paddle3:b18,paddle4:b19,leftx:a0,lefty:a1,rightx:a2,righty:a3,lefttrigger:a4,righttrigger:a5,");
                 {
                     const char *name = SDL_GetGamepadName(gamepad);
                     SDLTest_AssertCheck(SDL_strcmp(name, "Virtual PS4 Gamepad") == 0, "SDL_GetGamepadName() -> \"%s\" (expected \"%s\")", name, "Virtual PS4 Gamepad");
@@ -192,9 +206,75 @@ static int SDLCALL TestVirtualJoystick(void *arg)
     }
     SDLTest_AssertCheck(!SDL_IsJoystickVirtual(device_id), "!SDL_IsJoystickVirtual()");
 
-    SDL_ResetHint(SDL_HINT_JOYSTICK_ALLOW_BACKGROUND_EVENTS);
+    return TEST_COMPLETED;
+}
 
-    SDL_QuitSubSystem(SDL_INIT_GAMEPAD);
+/**
+ * Check gamepad mappings
+ */
+static int SDLCALL joystick_testMappings(void *arg)
+{
+    SDL_VirtualJoystickDesc desc;
+    SDL_Gamepad *gamepad = NULL;
+    SDL_JoystickID device_id;
+
+    /* Add a mapping for the virtual controller in advance */
+    SDL_AddGamepadMapping("ff000000550900001472000000007601,Virtual Gamepad,a:b0,b:b1,x:b2,y:b3,back:b4,guide:b5,start:b6,leftstick:b7,rightstick:b8,leftshoulder:b9,rightshoulder:b10,dpup:b11,dpdown:b12,dpleft:b13,dpright:b14,misc1:b15,paddle1:b16,paddle2:b17,paddle3:b18,paddle4:b19,leftx:a0,lefty:a1,rightx:a2,righty:a3,lefttrigger:a4,righttrigger:a5,");
+
+    SDL_INIT_INTERFACE(&desc);
+    desc.type = SDL_JOYSTICK_TYPE_GAMEPAD;
+    desc.naxes = SDL_GAMEPAD_AXIS_COUNT;
+    desc.nbuttons = SDL_GAMEPAD_BUTTON_COUNT;
+    desc.vendor_id = USB_VENDOR_NVIDIA;
+    desc.product_id = USB_PRODUCT_NVIDIA_SHIELD_CONTROLLER_V104;
+    desc.name = "Virtual NVIDIA SHIELD Controller";
+    device_id = SDL_AttachVirtualJoystick(&desc);
+    SDLTest_AssertCheck(device_id > 0, "SDL_AttachVirtualJoystick() -> %" SDL_PRIs32 " (expected > 0)", device_id);
+    SDLTest_AssertCheck(SDL_IsJoystickVirtual(device_id), "SDL_IsJoystickVirtual()");
+
+    gamepad = SDL_OpenGamepad(device_id);
+    SDLTest_AssertCheck(gamepad != NULL, "SDL_OpenGamepad() succeeded");
+    if (gamepad) {
+        /* Verify that the gamepad picked up the predefined mapping */
+        {
+            const char *name = SDL_GetGamepadName(gamepad);
+            SDLTest_AssertCheck(name && SDL_strcmp(name, "Virtual Gamepad") == 0, "SDL_GetGamepadName() ->\"%s\" (expected \"%s\")", name, "Virtual Gamepad");
+        }
+
+        /* Verify that the gamepad picks up a new mapping with no CRC */
+        SDL_AddGamepadMapping("ff000000550900001472000000007601,Virtual Gamepad V2,a:b0,b:b1,x:b2,y:b3,back:b4,guide:b5,start:b6,leftstick:b7,rightstick:b8,leftshoulder:b9,rightshoulder:b10,dpup:b11,dpdown:b12,dpleft:b13,dpright:b14,misc1:b15,paddle1:b16,paddle2:b17,paddle3:b18,paddle4:b19,leftx:a0,lefty:a1,rightx:a2,righty:a3,lefttrigger:a4,righttrigger:a5,");
+        {
+            const char *name = SDL_GetGamepadName(gamepad);
+            SDLTest_AssertCheck(name && SDL_strcmp(name, "Virtual Gamepad V2") == 0, "SDL_GetGamepadName() ->\"%s\" (expected \"%s\")", name, "Virtual Gamepad V2");
+        }
+
+        /* Verify that the gamepad picks up a new mapping with valid CRC */
+        SDL_AddGamepadMapping("ff008316550900001472000000007601,Virtual Gamepad V3,a:b0,b:b1,x:b2,y:b3,back:b4,guide:b5,start:b6,leftstick:b7,rightstick:b8,leftshoulder:b9,rightshoulder:b10,dpup:b11,dpdown:b12,dpleft:b13,dpright:b14,misc1:b15,paddle1:b16,paddle2:b17,paddle3:b18,paddle4:b19,leftx:a0,lefty:a1,rightx:a2,righty:a3,lefttrigger:a4,righttrigger:a5,");
+        {
+            const char *name = SDL_GetGamepadName(gamepad);
+            SDLTest_AssertCheck(name && SDL_strcmp(name, "Virtual Gamepad V3") == 0, "SDL_GetGamepadName() ->\"%s\" (expected \"%s\")", name, "Virtual Gamepad V3");
+        }
+
+        SDL_CloseGamepad(gamepad);
+    }
+    SDLTest_AssertCheck(SDL_DetachVirtualJoystick(device_id), "SDL_DetachVirtualJoystick()");
+
+    /* Try matching mappings with a new CRC */
+    desc.name = "Virtual NVIDIA SHIELD Controller V2";
+    device_id = SDL_AttachVirtualJoystick(&desc);
+    SDLTest_AssertCheck(device_id > 0, "SDL_AttachVirtualJoystick() -> %" SDL_PRIs32 " (expected > 0)", device_id);
+    SDLTest_AssertCheck(SDL_IsJoystickVirtual(device_id), "SDL_IsJoystickVirtual()");
+
+    gamepad = SDL_OpenGamepad(device_id);
+    SDLTest_AssertCheck(gamepad != NULL, "SDL_OpenGamepad() succeeded");
+    if (gamepad) {
+        {
+            const char *name = SDL_GetGamepadName(gamepad);
+            SDLTest_AssertCheck(name && SDL_strcmp(name, "Virtual Gamepad V2") == 0, "SDL_GetGamepadName() ->\"%s\" (expected \"%s\")", name, "Virtual Gamepad V2");
+        }
+        SDL_CloseGamepad(gamepad);
+    }
+    SDLTest_AssertCheck(SDL_DetachVirtualJoystick(device_id), "SDL_DetachVirtualJoystick()");
 
     return TEST_COMPLETED;
 }
@@ -203,19 +283,23 @@ static int SDLCALL TestVirtualJoystick(void *arg)
 
 /* Joystick routine test cases */
 static const SDLTest_TestCaseReference joystickTest1 = {
-    TestVirtualJoystick, "TestVirtualJoystick", "Test virtual joystick functionality", TEST_ENABLED
+    joystick_testVirtual, "joystick_testVirtual", "Test virtual joystick functionality", TEST_ENABLED
+};
+static const SDLTest_TestCaseReference joystickTest2 = {
+    joystick_testMappings, "joystick_testMappings", "Test gamepad mapping functionality", TEST_ENABLED
 };
 
 /* Sequence of Joystick routine test cases */
 static const SDLTest_TestCaseReference *joystickTests[] = {
     &joystickTest1,
+    &joystickTest2,
     NULL
 };
 
 /* Joystick routine test suite (global) */
 SDLTest_TestSuiteReference joystickTestSuite = {
     "Joystick",
-    NULL,
+    joystickSetUp,
     joystickTests,
-    NULL
+    joystickTearDown
 };