Prototype adapter XInput feasibility

xinput_feasibility_protocol.h

@@ -0,0 +1,87 @@
+#pragma once
+
+#include <stdint.h>
+
+#include "switch_pro_driver.h"
+
+namespace XInputFeasibility {
+
+constexpr uint16_t kDpadUp = 0x0001;
+constexpr uint16_t kDpadDown = 0x0002;
+constexpr uint16_t kDpadLeft = 0x0004;
+constexpr uint16_t kDpadRight = 0x0008;
+constexpr uint16_t kStart = 0x0010;
+constexpr uint16_t kBack = 0x0020;
+constexpr uint16_t kLeftThumb = 0x0040;
+constexpr uint16_t kRightThumb = 0x0080;
+constexpr uint16_t kLeftShoulder = 0x0100;
+constexpr uint16_t kRightShoulder = 0x0200;
+constexpr uint16_t kGuide = 0x0400;
+constexpr uint16_t kButtonA = 0x1000;
+constexpr uint16_t kButtonB = 0x2000;
+constexpr uint16_t kButtonX = 0x4000;
+constexpr uint16_t kButtonY = 0x8000;
+
+#pragma pack(push, 1)
+struct InputReport {
+    uint8_t report_id;
+    uint8_t report_size;
+    uint16_t buttons;
+    uint8_t left_trigger;
+    uint8_t right_trigger;
+    int16_t left_x;
+    int16_t left_y;
+    int16_t right_x;
+    int16_t right_y;
+    uint8_t reserved[6];
+};
+#pragma pack(pop)
+
+static_assert(sizeof(InputReport) == 20);
+
+constexpr int16_t horizontal_axis(uint16_t value) {
+    return static_cast<int16_t>(static_cast<int32_t>(value) - 32768);
+}
+
+constexpr int16_t vertical_axis(uint16_t value) {
+    const int16_t horizontal = horizontal_axis(value);
+    return horizontal == INT16_MIN ? INT16_MAX
+                                   : static_cast<int16_t>(-horizontal);
+}
+
+inline InputReport build_input_report(const SwitchInputState &state) {
+    InputReport report{};
+    report.report_size = sizeof(report);
+    report.buttons =
+        (state.dpad_up ? kDpadUp : 0) | (state.dpad_down ? kDpadDown : 0) |
+        (state.dpad_left ? kDpadLeft : 0) |
+        (state.dpad_right ? kDpadRight : 0) | (state.button_plus ? kStart : 0) |
+        (state.button_minus ? kBack : 0) | (state.button_l3 ? kLeftThumb : 0) |
+        (state.button_r3 ? kRightThumb : 0) |
+        (state.button_l ? kLeftShoulder : 0) |
+        (state.button_r ? kRightShoulder : 0) |
+        (state.button_home ? kGuide : 0) |
+        // Switch labels are positional opposites of XInput labels.
+        (state.button_b ? kButtonA : 0) | (state.button_a ? kButtonB : 0) |
+        (state.button_y ? kButtonX : 0) | (state.button_x ? kButtonY : 0);
+    report.left_trigger = state.button_zl ? 0xff : 0x00;
+    report.right_trigger = state.button_zr ? 0xff : 0x00;
+    report.left_x = horizontal_axis(state.lx);
+    report.left_y = vertical_axis(state.ly);
+    report.right_x = horizontal_axis(state.rx);
+    report.right_y = vertical_axis(state.ry);
+    return report;
+}
+
+inline bool parse_rumble_report(const uint8_t *data, uint32_t size,
+                                SwitchRumbleOutput *output) {
+    if (data == nullptr || output == nullptr || size < 5 || data[0] != 0x00 ||
+        data[1] != 0x08) {
+        return false;
+    }
+    output->low_frequency_magnitude = data[3];
+    output->high_frequency_magnitude = data[4];
+    return true;
+}
+
+} // namespace XInputFeasibility