rift_internal.h

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// Copyright 2025, Beyley Cardellio
// SPDX-License-Identifier: BSL-1.0
/*!
 * @file
 * @brief  Interface to Oculus Rift driver code.
 * @author Beyley Cardellio <ep1cm1n10n123@gmail.com>
 * @ingroup drv_rift
 */
 
#pragma once
 
#include "xrt/xrt_byte_order.h"
 
#include "util/u_device.h"
#include "util/u_logging.h"
 
#include "math/m_imu_3dof.h"
#include "math/m_api.h"
#include "math/m_mathinclude.h"
 
#include "os/os_hid.h"
#include "os/os_threading.h"
 
#include <stdlib.h>
#include <stdio.h>
#include <assert.h>
 
#include "rift_interface.h"
 
 
#define HMD_TRACE(hmd, ...) U_LOG_XDEV_IFL_T(&hmd->base, hmd->log_level, __VA_ARGS__)
#define HMD_DEBUG(hmd, ...) U_LOG_XDEV_IFL_D(&hmd->base, hmd->log_level, __VA_ARGS__)
#define HMD_INFO(hmd, ...) U_LOG_XDEV_IFL_I(&hmd->base, hmd->log_level, __VA_ARGS__)
#define HMD_WARN(hmd, ...) U_LOG_XDEV_IFL_W(&hmd->base, hmd->log_level, __VA_ARGS__)
#define HMD_ERROR(hmd, ...) U_LOG_XDEV_IFL_E(&hmd->base, hmd->log_level, __VA_ARGS__)
 
#define REPORT_MAX_SIZE 69                // max size of a feature report (FEATURE_REPORT_CALIBRATE)
#define KEEPALIVE_INTERVAL_NS 10000000000 // 10 seconds
// give a 5% breathing room (at 10 seconds, this is 500 milliseconds of breathing room)
#define KEEPALIVE_SEND_RATE_NS ((KEEPALIVE_INTERVAL_NS * 19) / 20)
#define IMU_SAMPLE_RATE (1000)      // 1000hz
#define NS_PER_SAMPLE (1000 * 1000) // 1ms (1,000,000 ns) per sample
#define SERIAL_NUMBER_LENGTH 14
 
#define CALIBRATION_HASH_BYTE_OFFSET 0x1bf0
#define CALIBRATION_HASH_BYTE_LENGTH 0x10
 
#define CALIBRATION_HEADER_BYTE_OFFSET 0x0
#define CALIBRATION_HEADER_BYTE_LENGTH 0x4
 
#define CALIBRATION_BODY_BYTE_OFFSET 0x4
#define CALIBRATION_BODY_BYTE_CHUNK_LENGTH 0x14
 
#define MICROMETERS_TO_METERS(microns) ((float)microns / 1000000.0f)
 
// value taken from LibOVR 0.4.4
#define DEFAULT_EXTRA_EYE_ROTATION DEG_TO_RAD(30.0f)
 
#define IN_REPORT_DK2 11                 // sent on the HMD HID interface
#define IN_REPORT_RADIO_DATA 12          // sent on the radio HID interface
#define IN_REPORT_CV1_RADIO_KEEPALIVE 13 // sent on the HMD HID interface when no devices are connected
 
#define IN_REPORT_RADIO_DATA_SIZE 64
 
#ifdef __cplusplus
extern "C" {
#endif
 
// asserts the size of a type is equal to the byte size provided
#define SIZE_ASSERT(type, size)                                                                                        \
        static_assert(sizeof(type) == (size), "Size of " #type " is not " #size " bytes as was expected")
 
enum rift_feature_reports
{
        // DK1
        FEATURE_REPORT_CONFIG = 2,         // get + set
        FEATURE_REPORT_CALIBRATE = 3,      // get + set
        FEATURE_REPORT_RANGE = 4,          // get + set
        FEATURE_REPORT_REGISTER = 5,       // get + set
        FEATURE_REPORT_DFU = 6,            // get + set
        FEATURE_REPORT_DK1_KEEP_ALIVE = 8, // get + set
        FEATURE_REPORT_DISPLAY_INFO = 9,   // get + set
        FEATURE_REPORT_SERIAL = 10,        // get + set
 
        // DK2
        FEATURE_REPORT_TRACKING = 12,        // get + set
        FEATURE_REPORT_DISPLAY = 13,         // get + set
        FEATURE_REPORT_MAG_CALIBRATION = 14, // get + set
        FEATURE_REPORT_POS_CALIBRATION = 15, // get + set
        FEATURE_REPORT_CUSTOM_PATTERN = 16,  // get + set
        FEATURE_REPORT_KEEPALIVE_MUX = 17,   // get + set
        FEATURE_REPORT_MANUFACTURING = 18,   // get + set
        FEATURE_REPORT_UUID = 19,            // get + set
        FEATURE_REPORT_TEMPERATURE = 20,     // get + set
        FEATURE_REPORT_GYROOFFSET = 21,      // get only
        FEATURE_REPORT_LENS_DISTORTION = 22, // get + set
 
        // CV1
        FEATURE_REPORT_RADIO_CONTROL = 26,       // get + set
        FEATURE_REPORT_RADIO_READ_DATA_CMD = 27, // @todo: get + ???
        FEATURE_REPORT_ENABLE_COMPONENTS = 29,   // @todo: ??? + set
};
 
enum rift_config_report_flags
{
        // output the sample data raw from the sensors without converting them to known units
        RIFT_CONFIG_REPORT_USE_RAW = 1,
        // internal test mode for calibrating zero rate drift on gyro
        RIFT_CONFIG_REPORT_INTERNAL_CALIBRATION = 1 << 1,
        // use the calibration parameters stored on the device
        RIFT_CONFIG_REPORT_USE_CALIBRATION = 1 << 2,
        // recalibrate the gyro zero rate offset when the device is stationary
        RIFT_CONFIG_REPORT_AUTO_CALIBRATION = 1 << 3,
        // stop sending IN reports when the device has stopped moving for Interval milliseconds
        RIFT_CONFIG_REPORT_MOTION_KEEP_ALIVE = 1 << 4,
        // stop sending IN reports when the device has stopped receiving feature reports for Interval milliseconds
        RIFT_CONFIG_REPORT_COMMAND_KEEP_ALIVE = 1 << 5,
        // output the IN report data in the coordinate system used by LibOVR relative to the tracker, otherwise, report
        // in the coordinate system of the device
        RIFT_CONFIG_REPORT_USE_SENSOR_COORDINATES = 1 << 6,
        // override the power state of the USB hub, forcing it to act as if the external power source is connected (DK2
        // only, does nothing on DK1)
        RIFT_CONFIG_REPORT_OVERRIDE_POWER = 1 << 7,
};
 
enum rift_distortion_type
{
        RIFT_DISTORTION_TYPE_DIMS = 1,
        RIFT_DISTORTION_TYPE_K = 2,
};
 
enum rift_lens_type
{
        // firmware indirectly states lens type A is 0
        RIFT_LENS_TYPE_A = 0,
        // firmware does not state what lens type B is, 1 is an educated guess
        RIFT_LENS_TYPE_B = 1,
};
 
enum rift_lens_distortion_version
{
        // no distortion data is stored
        RIFT_LENS_DISTORTION_NONE = 0,
        // standard distortion matrix
        RIFT_LENS_DISTORTION_LCSV_CATMULL_ROM_10_VERSION_1 = 1,
};
 
enum rift_component_flags
{
        RIFT_COMPONENT_DISPLAY = 1 << 0,
        RIFT_COMPONENT_AUDIO = 1 << 1,
        RIFT_COMPONENT_LEDS = 1 << 2,
};
 
/*
 *
 * Packed structs for USB communication
 *
 */
 
#pragma pack(push, 1)
 
struct rift_config_report
{
        uint16_t command_id;
        uint8_t config_flags;
        // the IN report rate of the headset, rate is calculated as `sample_rate / (1 + interval)`
        uint8_t interval;
        // sample rate of the IMU, always 1000hz on DK1/DK2, read-only
        uint16_t sample_rate;
};
 
SIZE_ASSERT(struct rift_config_report, 6);
 
struct rift_display_info_report
{
        uint16_t command_id;
        uint8_t distortion_type;
        // the horizontal resolution of the display, in pixels
        uint16_t resolution_x;
        // the vertical resolution of the display, in pixels
        uint16_t resolution_y;
        // width in micrometers
        uint32_t display_width;
        // height in micrometers
        uint32_t display_height;
        // the vertical center of the display, in micrometers
        uint32_t center_v;
        // the separation between the two lenses, in micrometers
        uint32_t lens_separation;
        uint32_t lens_distance[2];
        float distortion[6];
};
 
SIZE_ASSERT(struct rift_display_info_report, 55);
 
#define CATMULL_COEFFICIENTS 11
#define CHROMATIC_ABBERATION_COEFFEICENT_COUNT 4
 
struct rift_catmull_rom_distortion_report_data
{
        // eye relief setting, in micrometers from front surface of lens
        uint16_t eye_relief;
        // the k coeffecients of the distortion
        uint16_t k[CATMULL_COEFFICIENTS];
        uint16_t max_r;
        uint16_t meters_per_tan_angle_at_center;
        uint16_t chromatic_abberation[CHROMATIC_ABBERATION_COEFFEICENT_COUNT];
        uint8_t unused[14];
};
 
SIZE_ASSERT(struct rift_catmull_rom_distortion_report_data, 50);
 
struct rift_lens_distortion_report
{
        uint16_t command_id;
        // the amount of distortions on this device
        uint8_t num_distortions;
        // the index of this distortion in the devices array
        uint8_t distortion_idx;
        // unused bitmask field
        uint8_t bitmask;
        // the type of the lenses
        uint16_t lens_type;
        // the version of the lens distortion data
        uint16_t distortion_version;
 
        union {
                struct rift_catmull_rom_distortion_report_data lcsv_catmull_rom_10;
        } data;
};
 
SIZE_ASSERT(struct rift_lens_distortion_report, 9 + sizeof(struct rift_catmull_rom_distortion_report_data));
 
struct rift_dk2_keepalive_mux_report
{
        uint16_t command;
        uint8_t in_report;
        uint16_t interval;
};
 
SIZE_ASSERT(struct rift_dk2_keepalive_mux_report, 5);
 
enum rift_display_mode
{
        RIFT_DISPLAY_MODE_GLOBAL,
        RIFT_DISPLAY_MODE_ROLLING_TOP_BOTTOM,
        RIFT_DISPLAY_MODE_ROLLING_LEFT_RIGHT,
        RIFT_DISPLAY_MODE_ROLLING_RIGHT_LEFT,
};
 
enum rift_display_limit
{
        RIFT_DISPLAY_LIMIT_ACL_OFF = 0,
        RIFT_DISPLAY_LIMIT_ACL_30 = 1,
        RIFT_DISPLAY_LIMIT_ACL_25 = 2,
        RIFT_DISPLAY_LIMIT_ACL_50 = 3,
};
 
enum rift_display_flags
{
        RIFT_DISPLAY_USE_ROLLING = 1 << 6,
        RIFT_DISPLAY_REVERSE_ROLLING = 1 << 7,
        RIFT_DISPLAY_HIGH_BRIGHTNESS = 1 << 8,
        RIFT_DISPLAY_SELF_REFRESH = 1 << 9,
        RIFT_DISPLAY_READ_PIXEL = 1 << 10,
        RIFT_DISPLAY_DIRECT_PENTILE = 1 << 11,
};
 
struct rift_display_report
{
        uint16_t command_id;
        // relative brightness setting independent of pixel persistence, only effective when high brightness is disabled
        uint8_t brightness;
        // a set of flags, ordered from LSB -> MSB
        // - panel mode/shutter type (4 bits), read only, see rift_display_mode
        // - current limit (2 bits), see rift_display_limit
        // - use rolling (1 bit)
        // - reverse rolling (1 bit), unavailable on released DK2 firmware for unknown reason
        // - high brightness (1 bit), unavailable on released DK2 firmware for unpublished reason
        // - self refresh (1 bit)
        // - read pixel (1 bit)
        // - direct pentile (1 bit)
        uint32_t flags;
        // the length of time in rows that the display is lit each frame, defaults to the full size of the display, full
        // persistence
        uint16_t persistence;
        // the offset in rows from vsync that the panel is lit when using global shutter, no effect in rolling shutter,
        // disabled on released DK2 firmware for unknown reason
        uint16_t lighting_offset;
        // the time in microseconds it is estimated for a pixel to settle to one value after it is set, read only
        uint16_t pixel_settle;
        // the number of rows including active area and blanking period used with persistence and lightingoffset, read
        // only
        uint16_t total_rows;
};
 
SIZE_ASSERT(struct rift_display_report, 15);
 
struct rift_dk2_sensor_sample
{
        uint8_t data[8];
};
 
SIZE_ASSERT(struct rift_dk2_sensor_sample, 8);
 
struct rift_dk2_sample_pack
{
        struct rift_dk2_sensor_sample accel;
        struct rift_dk2_sensor_sample gyro;
};
 
SIZE_ASSERT(struct rift_dk2_sample_pack, sizeof(struct rift_dk2_sensor_sample) * 2);
 
struct rift_dk2_version_data
{
        int16_t mag_x;
        int16_t mag_y;
        int16_t mag_z;
};
 
SIZE_ASSERT(struct rift_dk2_version_data, 6);
 
struct rift_cv1_version_data
{
        uint16_t presence_sensor;
        uint16_t iad_adc_value;
        uint16_t unk;
};
 
SIZE_ASSERT(struct rift_cv1_version_data, 6);
static_assert(sizeof(struct rift_cv1_version_data) == sizeof(struct rift_dk2_version_data),
              "Incorrect version data size");
 
#define DK2_MAX_SAMPLES 2
struct dk2_in_report
{
        uint16_t command_id;
        uint8_t num_samples;
        uint16_t sample_count;
        uint16_t temperature;
        uint32_t sample_timestamp;
        struct rift_dk2_sample_pack samples[DK2_MAX_SAMPLES];
        union {
                struct rift_dk2_version_data dk2;
                struct rift_cv1_version_data cv1;
        };
        uint16_t frame_count;
        uint32_t frame_timestamp;
        uint8_t frame_id;
        uint8_t tracking_pattern;
        uint16_t tracking_count;
        uint32_t tracking_timestamp;
};
 
SIZE_ASSERT(struct dk2_in_report, 63);
 
struct rift_enable_components_report
{
        uint16_t command_id;
        // which components to enable, see rift_component_flags
        uint8_t flags;
};
 
SIZE_ASSERT(struct rift_enable_components_report, 3);
 
struct rift_imu_calibration_report
{
        uint16_t command_id;
        struct rift_dk2_sample_pack offset;
        struct rift_dk2_sample_pack matrix_samples[3];
        uint16_t temperature;
};
 
SIZE_ASSERT(struct rift_imu_calibration_report, sizeof(struct rift_dk2_sample_pack) * 4 + 4);
 
enum rift_radio_read_cmd
{
        RIFT_RADIO_READ_CMD_FLASH_CONTROL = 0x0a,
        RIFT_RADIO_READ_CMD_SERIAL = 0x88,
};
 
struct rift_radio_cmd_report
{
        uint16_t command_id;
        uint8_t a;
        uint8_t b;
        uint8_t c;
};
 
SIZE_ASSERT(struct rift_radio_cmd_report, 5);
 
struct rift_radio_data_read_cmd
{
        uint16_t command_id;
        uint16_t offset;
        uint16_t length;
        uint8_t unk[28];
};
 
SIZE_ASSERT(struct rift_radio_data_read_cmd, 34);
 
struct rift_radio_flash_read_response_header
{
        uint8_t unk[5];
        __le16 data_length;
};
SIZE_ASSERT(struct rift_radio_flash_read_response_header, 7);
 
struct rift_radio_address_radio_report
{
        uint16_t command_id;
        uint8_t radio_address[5];
};
 
SIZE_ASSERT(struct rift_radio_address_radio_report, 7);
 
enum rift_radio_report_remote_button_masks
{
        RIFT_REMOTE_BUTTON_MASK_DPAD_UP = 0x001,
        RIFT_REMOTE_BUTTON_MASK_DPAD_DOWN = 0x002,
        RIFT_REMOTE_BUTTON_MASK_DPAD_LEFT = 0x004,
        RIFT_REMOTE_BUTTON_MASK_DPAD_RIGHT = 0x008,
        RIFT_REMOTE_BUTTON_MASK_SELECT = 0x010,
        RIFT_REMOTE_BUTTON_MASK_VOLUME_UP = 0x020,
        RIFT_REMOTE_BUTTON_MASK_VOLUME_DOWN = 0x040,
        RIFT_REMOTE_BUTTON_MASK_OCULUS = 0x080,
        RIFT_REMOTE_BUTTON_MASK_BACK = 0x100,
};
 
struct rift_radio_report_remote_message
{
        // the button state of the controller, see rift_radio_report_remote_button_masks
        uint16_t buttons;
};
 
SIZE_ASSERT(struct rift_radio_report_remote_message, 2);
 
enum rift_radio_report_touch_buttons
{
        RIFT_TOUCH_CONTROLLER_BUTTON_A = 0x01,
        RIFT_TOUCH_CONTROLLER_BUTTON_X = 0x01,
        RIFT_TOUCH_CONTROLLER_BUTTON_B = 0x02,
        RIFT_TOUCH_CONTROLLER_BUTTON_Y = 0x02,
        RIFT_TOUCH_CONTROLLER_BUTTON_MENU = 0x04,
        RIFT_TOUCH_CONTROLLER_BUTTON_OCULUS = 0x04,
        RIFT_TOUCH_CONTROLLER_BUTTON_STICK = 0x08,
};
 
struct rift_radio_report_touch_message
{
        uint32_t timestamp;
        int16_t accel[3];
        int16_t gyro[3];
        uint8_t buttons;
        uint8_t touch_grip_stick_state[5];
        // see rift_radio_report_adc_channel
        uint8_t adc_channel;
        uint16_t adc_value;
};
 
SIZE_ASSERT(struct rift_radio_report_touch_message, 25);
 
enum rift_radio_device_type
{
        RIFT_RADIO_DEVICE_REMOTE = 1,
        RIFT_RADIO_DEVICE_LEFT_TOUCH = 2,
        RIFT_RADIO_DEVICE_RIGHT_TOUCH = 3,
        RIFT_RADIO_DEVICE_TRACKED_OBJECT = 6,
};
 
struct rift_radio_report_message
{
        uint16_t flags;
        // the type of device sending the message, see rift_radio_device_type
        uint8_t device_type;
        union {
                struct rift_radio_report_remote_message remote;
                struct rift_radio_report_touch_message touch;
        };
};
 
SIZE_ASSERT(struct rift_radio_report_message, 3 + sizeof(struct rift_radio_report_touch_message));
 
struct rift_radio_report
{
        uint16_t command_id;
        struct rift_radio_report_message messages[2];
};
 
#pragma pack(pop)
 
/*
 *
 * Parsed structs for internal use
 *
 */
 
struct rift_catmull_rom_distortion_data
{
        // the k coeffecients of the distortion
        float k[CATMULL_COEFFICIENTS];
        float max_r;
        float meters_per_tan_angle_at_center;
        float chromatic_abberation[CHROMATIC_ABBERATION_COEFFEICENT_COUNT];
};
 
struct rift_lens_distortion
{
        // the version of the lens distortion data
        uint16_t distortion_version;
        // eye relief setting, in meters from surface of lens
        float eye_relief;
 
        union {
                struct rift_catmull_rom_distortion_data lcsv_catmull_rom_10;
        } data;
};
 
struct rift_scale_and_offset
{
        struct xrt_vec2 scale;
        struct xrt_vec2 offset;
};
 
struct rift_viewport_fov_tan
{
        float up_tan;
        float down_tan;
        float left_tan;
        float right_tan;
};
 
struct rift_extra_display_info
{
        // gap left between the two eyes
        float screen_gap_meters;
        // the diameter of the lenses, may need to be extended to an array
        float lens_diameter_meters;
        // ipd of the headset
        float icd;
 
        // the fov of the headset
        struct rift_viewport_fov_tan fov;
        // mapping from tan-angle space to target NDC space
        struct rift_scale_and_offset eye_to_source_ndc;
        struct rift_scale_and_offset eye_to_source_uv;
};
 
struct rift_imu_calibration
{
        struct xrt_vec3 gyro_offset;
        struct xrt_vec3 accel_offset;
        struct xrt_matrix_3x3 gyro_matrix;
        struct xrt_matrix_3x3 accel_matrix;
        float temperature;
};
 
enum rift_touch_controller_input
{
        // left
        RIFT_TOUCH_CONTROLLER_INPUT_X_CLICK = 0,
        RIFT_TOUCH_CONTROLLER_INPUT_X_TOUCH = 1,
        RIFT_TOUCH_CONTROLLER_INPUT_Y_CLICK = 2,
        RIFT_TOUCH_CONTROLLER_INPUT_Y_TOUCH = 3,
        RIFT_TOUCH_CONTROLLER_INPUT_SYSTEM_CLICK = 4,
        // right
        RIFT_TOUCH_CONTROLLER_INPUT_A_CLICK = 0,
        RIFT_TOUCH_CONTROLLER_INPUT_A_TOUCH = 1,
        RIFT_TOUCH_CONTROLLER_INPUT_B_CLICK = 2,
        RIFT_TOUCH_CONTROLLER_INPUT_B_TOUCH = 3,
        RIFT_TOUCH_CONTROLLER_INPUT_MENU_CLICK = 4,
        // both
        RIFT_TOUCH_CONTROLLER_INPUT_SQUEEZE_VALUE = 5,
        RIFT_TOUCH_CONTROLLER_INPUT_TRIGGER_TOUCH = 6,
        RIFT_TOUCH_CONTROLLER_INPUT_TRIGGER_VALUE = 7,
        RIFT_TOUCH_CONTROLLER_INPUT_THUMBSTICK_CLICK = 8,
        RIFT_TOUCH_CONTROLLER_INPUT_THUMBSTICK_TOUCH = 9,
        RIFT_TOUCH_CONTROLLER_INPUT_THUMBSTICK = 10,
        RIFT_TOUCH_CONTROLLER_INPUT_THUMBREST_TOUCH = 11,
        RIFT_TOUCH_CONTROLLER_INPUT_GRIP_POSE = 12,
        RIFT_TOUCH_CONTROLLER_INPUT_AIM_POSE = 13,
        RIFT_TOUCH_CONTROLLER_INPUT_TRIGGER_PROXIMITY = 14,
        RIFT_TOUCH_CONTROLLER_INPUT_THUMB_PROXIMITY = 15,
        RIFT_TOUCH_CONTROLLER_INPUT_COUNT = 16,
};
 
struct rift_touch_controller_led
{
        struct xrt_vec3 position;
        struct xrt_vec3 normal;
        struct xrt_vec3 angles;
};
 
struct rift_touch_controller_calibration
{
        uint16_t joy_x_range[2];
        uint16_t joy_x_dead[2];
        uint16_t joy_y_range[2];
        uint16_t joy_y_dead[2];
 
        // min - mid - max
        uint16_t trigger_range[3];
 
        // min - mid - max
        uint16_t middle_range[3];
        bool middle_flipped;
 
        uint16_t cap_sense_min[8];
        uint16_t cap_sense_touch[8];
 
        float gyro_calibration[3][3];
        struct xrt_vec3 gyro_offset;
        float accel_calibration[3][3];
        struct xrt_vec3 accel_offset;
 
        struct xrt_vec3 imu_position;
 
        size_t num_leds;
        struct rift_touch_controller_led *leds;
};
 
struct rift_touch_controller_input_state
{
        uint8_t buttons;
        float trigger;
        float grip;
        float stick[2];
        uint8_t haptic_counter;
        float cap_stick;
        float cap_b_y;
        float cap_a_x;
        float cap_trigger;
        float cap_thumbrest;
};
 
/*!
 * A Rift Touch controller device.
 *
 * @implements xrt_device
 */
struct rift_touch_controller
{
        struct xrt_device base;
 
        struct rift_hmd *hmd;
 
        enum rift_radio_device_type device_type;
 
        struct
        {
                bool mutex_created;
                struct os_mutex mutex;
 
                struct rift_touch_controller_input_state state;
 
                bool calibration_read;
                struct rift_touch_controller_calibration calibration;
        } input;
 
 
        //! Locked by radio_state.thread
        struct
        {
                bool serial_valid;
 
                uint8_t calibration_hash[CALIBRATION_HASH_BYTE_LENGTH];
 
                uint8_t calibration_data_buffer[CALIBRATION_BODY_BYTE_CHUNK_LENGTH];
 
                uint8_t *calibration_body_json;
                uint16_t calibration_body_json_length;
 
        } radio_data;
};
 
enum rift_remote_inputs
{
        RIFT_REMOTE_INPUT_DPAD_UP,
        RIFT_REMOTE_INPUT_DPAD_DOWN,
        RIFT_REMOTE_INPUT_DPAD_LEFT,
        RIFT_REMOTE_INPUT_DPAD_RIGHT,
        RIFT_REMOTE_INPUT_SELECT,
        RIFT_REMOTE_INPUT_VOLUME_UP,
        RIFT_REMOTE_INPUT_VOLUME_DOWN,
        RIFT_REMOTE_INPUT_BACK,
        RIFT_REMOTE_INPUT_OCULUS,
        RIFT_REMOTE_INPUT_COUNT,
};
 
/*!
 * A Rift Remote device.
 *
 * @implements xrt_device
 */
struct rift_remote
{
        struct xrt_device base;
 
        //! The button state of the remote, stored as an atomic to avoid needing a mutex.
        xrt_atomic_s32_t buttons;
 
        //! Locked by radio_state.thread
        bool serial_valid;
};
 
enum rift_radio_command
{
        RIFT_RADIO_COMMAND_NONE = 0,
        RIFT_RADIO_COMMAND_READ_SERIAL,
        RIFT_RADIO_COMMAND_READ_FLASH,
};
 
struct rift_radio_command_data_read_serial
{
        //! A pointer to store the serial string. Must contain at least SERIAL_NUMBER_LENGTH bytes.
        char *serial;
        //! A pointer to store when reading the serial was successful.
        bool *serial_valid;
};
 
typedef int (*flash_read_callback_t)(void *user_data, uint16_t address, uint16_t length);
 
struct rift_radio_command_data_read_flash
{
        void *user_data;
 
        uint16_t address;
        uint16_t length;
 
        uint8_t *buffer;
 
        flash_read_callback_t read_callback;
};
 
union rift_radio_command_data {
        struct rift_radio_command_data_read_serial read_serial;
        struct rift_radio_command_data_read_flash read_flash;
};
 
/*!
 * A rift HMD device.
 *
 * @implements xrt_device
 */
struct rift_hmd
{
        struct xrt_device base;
 
        enum u_logging_level log_level;
 
        // has built-in mutex so thread safe
        struct m_relation_history *relation_hist;
 
        struct os_hid_device *hmd_dev;
        struct os_hid_device *radio_dev;
 
        struct os_thread_helper sensor_thread;
        bool processed_sample_packet;
        uint32_t last_remote_sample_time_us;
        timepoint_ns last_remote_sample_time_ns;
        timepoint_ns last_sample_local_timestamp_ns;
 
        struct m_imu_3dof fusion;
        struct m_clock_windowed_skew_tracker *clock_tracker;
 
        timepoint_ns last_keepalive_time;
        enum rift_variant variant;
        struct rift_config_report config;
        struct rift_display_info_report display_info;
 
        const struct rift_lens_distortion *lens_distortions;
        uint16_t num_lens_distortions;
        uint16_t distortion_in_use;
 
        struct rift_extra_display_info extra_display_info;
        float icd_override_m;
 
        bool presence;
 
        bool imu_needs_calibration;
        struct rift_imu_calibration imu_calibration;
 
        uint8_t radio_address[5];
 
        //! Mutex to protect access to the device array, device count == -1 means uninitialized
        struct os_mutex device_mutex;
 
        int device_count;
        int added_devices;
        struct xrt_device *devices[4]; // left touch, right touch, tracked object, remote
 
        //! Generic state for the radio state machine
        struct
        {
                struct os_thread_helper thread;
 
                struct rift_touch_controller *touch_controllers[3];
                struct rift_remote *remote;
 
                enum rift_radio_command current_command;
                union rift_radio_command_data command_data;
        } radio_state;
};
 
/// Casting helper function
static inline struct rift_hmd *
rift_hmd(struct xrt_device *xdev)
{
        return (struct rift_hmd *)xdev;
}
 
static inline struct rift_touch_controller *
rift_touch_controller(struct xrt_device *xdev)
{
        return (struct rift_touch_controller *)xdev;
}
 
static inline struct rift_remote *
rift_remote(struct xrt_device *xdev)
{
        return (struct rift_remote *)xdev;
}
 
static inline size_t
rift_radio_device_type_to_touch_index(enum rift_radio_device_type device_type)
{
        switch (device_type) {
        case RIFT_RADIO_DEVICE_LEFT_TOUCH: return 0;
        case RIFT_RADIO_DEVICE_RIGHT_TOUCH: return 1;
        case RIFT_RADIO_DEVICE_TRACKED_OBJECT: return 2;
        default: assert(false);
        }
 
        return -1;
}
 
static inline enum rift_radio_device_type
rift_radio_touch_index_to_device_type(size_t index)
{
        switch (index) {
        case 0: return RIFT_RADIO_DEVICE_LEFT_TOUCH;
        case 1: return RIFT_RADIO_DEVICE_RIGHT_TOUCH;
        case 2: return RIFT_RADIO_DEVICE_TRACKED_OBJECT;
        default: assert(false);
        }
 
        return (enum rift_radio_device_type)0;
}
 
bool
rift_touch_calibration_parse(const char *calibration_data,
                             size_t calibration_size,
                             struct rift_touch_controller_calibration *out_calibration);
 
#ifdef __cplusplus
} // extern "C"
#endif