1 files changed, 168 insertions, 0 deletions

diff --git a/SDL-3.2.8/src/core/linux/SDL_evdev_capabilities.c b/SDL-3.2.8/src/core/linux/SDL_evdev_capabilities.c
new file mode 100644
index 0000000..61e240e
--- /dev/null
+++ b/SDL-3.2.8/src/core/linux/SDL_evdev_capabilities.c
@@ -0,0 +1,168 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2025 Sam Lantinga <slouken@libsdl.org>
+  Copyright (C) 2020 Collabora Ltd.
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+#include "SDL_internal.h"
+
+#include "SDL_evdev_capabilities.h"
+
+#ifdef HAVE_LINUX_INPUT_H
+
+// missing defines in older Linux kernel headers
+#ifndef BTN_TRIGGER_HAPPY
+#define BTN_TRIGGER_HAPPY 0x2c0
+#endif
+#ifndef BTN_DPAD_UP
+#define BTN_DPAD_UP 0x220
+#endif
+#ifndef KEY_ALS_TOGGLE
+#define KEY_ALS_TOGGLE 0x230
+#endif
+
+extern int
+SDL_EVDEV_GuessDeviceClass(const unsigned long bitmask_props[NBITS(INPUT_PROP_MAX)],
+                           const unsigned long bitmask_ev[NBITS(EV_MAX)],
+                           const unsigned long bitmask_abs[NBITS(ABS_MAX)],
+                           const unsigned long bitmask_key[NBITS(KEY_MAX)],
+                           const unsigned long bitmask_rel[NBITS(REL_MAX)])
+{
+    struct range
+    {
+        unsigned start;
+        unsigned end;
+    };
+
+    // key code ranges above BTN_MISC (start is inclusive, stop is exclusive)
+    static const struct range high_key_blocks[] = {
+        { KEY_OK, BTN_DPAD_UP },
+        { KEY_ALS_TOGGLE, BTN_TRIGGER_HAPPY }
+    };
+
+    int devclass = 0;
+    unsigned long keyboard_mask;
+
+    // If the kernel specifically says it's an accelerometer, believe it
+    if (test_bit(INPUT_PROP_ACCELEROMETER, bitmask_props)) {
+        return SDL_UDEV_DEVICE_ACCELEROMETER;
+    }
+
+    // We treat pointing sticks as indistinguishable from mice
+    if (test_bit(INPUT_PROP_POINTING_STICK, bitmask_props)) {
+        return SDL_UDEV_DEVICE_MOUSE;
+    }
+
+    // We treat buttonpads as equivalent to touchpads
+    if (test_bit(INPUT_PROP_TOPBUTTONPAD, bitmask_props) ||
+        test_bit(INPUT_PROP_BUTTONPAD, bitmask_props) ||
+        test_bit(INPUT_PROP_SEMI_MT, bitmask_props)) {
+        return SDL_UDEV_DEVICE_TOUCHPAD;
+    }
+
+    // X, Y, Z axes but no buttons probably means an accelerometer
+    if (test_bit(EV_ABS, bitmask_ev) &&
+        test_bit(ABS_X, bitmask_abs) &&
+        test_bit(ABS_Y, bitmask_abs) &&
+        test_bit(ABS_Z, bitmask_abs) &&
+        !test_bit(EV_KEY, bitmask_ev)) {
+        return SDL_UDEV_DEVICE_ACCELEROMETER;
+    }
+
+    /* RX, RY, RZ axes but no buttons probably means a gyro or
+     * accelerometer (we don't distinguish) */
+    if (test_bit(EV_ABS, bitmask_ev) &&
+        test_bit(ABS_RX, bitmask_abs) &&
+        test_bit(ABS_RY, bitmask_abs) &&
+        test_bit(ABS_RZ, bitmask_abs) &&
+        !test_bit(EV_KEY, bitmask_ev)) {
+        return SDL_UDEV_DEVICE_ACCELEROMETER;
+    }
+
+    if (test_bit(EV_ABS, bitmask_ev) &&
+        test_bit(ABS_X, bitmask_abs) && test_bit(ABS_Y, bitmask_abs)) {
+        if (test_bit(BTN_STYLUS, bitmask_key) || test_bit(BTN_TOOL_PEN, bitmask_key)) {
+            ; // ID_INPUT_TABLET
+        } else if (test_bit(BTN_TOOL_FINGER, bitmask_key) && !test_bit(BTN_TOOL_PEN, bitmask_key)) {
+            devclass |= SDL_UDEV_DEVICE_TOUCHPAD; // ID_INPUT_TOUCHPAD
+        } else if (test_bit(BTN_MOUSE, bitmask_key)) {
+            devclass |= SDL_UDEV_DEVICE_MOUSE; // ID_INPUT_MOUSE
+        } else if (test_bit(BTN_TOUCH, bitmask_key)) {
+            /* TODO: better determining between touchscreen and multitouch touchpad,
+               see https://github.com/systemd/systemd/blob/master/src/udev/udev-builtin-input_id.c */
+            devclass |= SDL_UDEV_DEVICE_TOUCHSCREEN; // ID_INPUT_TOUCHSCREEN
+        }
+
+        if (test_bit(BTN_TRIGGER, bitmask_key) ||
+            test_bit(BTN_A, bitmask_key) ||
+            test_bit(BTN_1, bitmask_key) ||
+            test_bit(ABS_RX, bitmask_abs) ||
+            test_bit(ABS_RY, bitmask_abs) ||
+            test_bit(ABS_RZ, bitmask_abs) ||
+            test_bit(ABS_THROTTLE, bitmask_abs) ||
+            test_bit(ABS_RUDDER, bitmask_abs) ||
+            test_bit(ABS_WHEEL, bitmask_abs) ||
+            test_bit(ABS_GAS, bitmask_abs) ||
+            test_bit(ABS_BRAKE, bitmask_abs)) {
+            devclass |= SDL_UDEV_DEVICE_JOYSTICK; // ID_INPUT_JOYSTICK
+        }
+    }
+
+    if (test_bit(EV_REL, bitmask_ev) &&
+        test_bit(REL_X, bitmask_rel) && test_bit(REL_Y, bitmask_rel) &&
+        test_bit(BTN_MOUSE, bitmask_key)) {
+        devclass |= SDL_UDEV_DEVICE_MOUSE; // ID_INPUT_MOUSE
+    }
+
+    if (test_bit(EV_KEY, bitmask_ev)) {
+        unsigned i;
+        unsigned long found = 0;
+
+        for (i = 0; i < BTN_MISC / BITS_PER_LONG; ++i) {
+            found |= bitmask_key[i];
+        }
+        // If there are no keys in the lower block, check the higher blocks
+        if (!found) {
+            unsigned block;
+            for (block = 0; block < (sizeof(high_key_blocks) / sizeof(struct range)); ++block) {
+                for (i = high_key_blocks[block].start; i < high_key_blocks[block].end; ++i) {
+                    if (test_bit(i, bitmask_key)) {
+                        found = 1;
+                        break;
+                    }
+                }
+            }
+        }
+
+        if (found > 0) {
+            devclass |= SDL_UDEV_DEVICE_HAS_KEYS; // ID_INPUT_KEY
+        }
+    }
+
+    /* the first 32 bits are ESC, numbers, and Q to D, so if we have all of
+     * those, consider it to be a fully-featured keyboard;
+     * do not test KEY_RESERVED, though */
+    keyboard_mask = 0xFFFFFFFE;
+    if ((bitmask_key[0] & keyboard_mask) == keyboard_mask) {
+        devclass |= SDL_UDEV_DEVICE_KEYBOARD; // ID_INPUT_KEYBOARD
+    }
+
+    return devclass;
+}
+
+#endif // HAVE_LINUX_INPUT_H