Win32: Fix underflow in deadzone logic

Fixes #910.

README.md

@@ -118,6 +118,7 @@ information on what to include when reporting a bug.
 - Bugfix: `glfwGetInstanceProcAddress` returned `NULL` for
           `vkGetInstanceProcAddr` when `_GLFW_VULKAN_STATIC` was enabled
 - [Win32] Bugfix: Undecorated windows could not be iconified by the user (#861)
+- [Win32] Bugfix: Deadzone logic could underflow with some controllers (#910)
 - [X11] Replaced `_GLFW_HAS_XF86VM` compile-time option with dynamic loading
 - [Cocoa] Added support for Vulkan window surface creation via MoltenVK (#870)
 - [Cocoa] Bugfix: Disabling window aspect ratio would assert (#852)
@@ -260,6 +261,7 @@ skills.
  - Arthur Tombs
  - Ioannis Tsakpinis
  - Samuli Tuomola
+ - Matthew Turner
  - urraka
  - Elias Vanderstuyft
  - Jari Vetoniemi

src/win32_joystick.c

@@ -603,9 +603,10 @@ static GLFWbool pollJoystickState(_GLFWjoystickWin32* js, int mode)
         if (mode == _GLFW_PRESENCE_ONLY)
             return GLFW_TRUE;
 
-        if (sqrt((double) (xis.Gamepad.sThumbLX * xis.Gamepad.sThumbLX +
-                           xis.Gamepad.sThumbLY * xis.Gamepad.sThumbLY)) >
-            (double) XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE)
+        if ((float) xis.Gamepad.sThumbLX * xis.Gamepad.sThumbLX +
+            (float) xis.Gamepad.sThumbLY * xis.Gamepad.sThumbLY >
+            (float) XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE *
+                    XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE)
         {
             js->axes[0] = (xis.Gamepad.sThumbLX + 0.5f) / 32767.f;
             js->axes[1] = (xis.Gamepad.sThumbLY + 0.5f) / 32767.f;
@@ -616,9 +617,10 @@ static GLFWbool pollJoystickState(_GLFWjoystickWin32* js, int mode)
             js->axes[1] = 0.f;
         }
 
-        if (sqrt((double) (xis.Gamepad.sThumbRX * xis.Gamepad.sThumbRX +
-                           xis.Gamepad.sThumbRY * xis.Gamepad.sThumbRY)) >
-            (double) XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE)
+        if ((float) xis.Gamepad.sThumbRX * xis.Gamepad.sThumbRX +
+            (float) xis.Gamepad.sThumbRY * xis.Gamepad.sThumbRY >
+            (float) XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE *
+                    XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE)
         {
             js->axes[2] = (xis.Gamepad.sThumbRX + 0.5f) / 32767.f;
             js->axes[3] = (xis.Gamepad.sThumbRY + 0.5f) / 32767.f;