/*
 * Copyright 2026 John Davis. All rights reserved.
 * Distributed under the terms of the MIT License.
 */
#ifndef _HYPERV_HID_PROTOCOL_H_
#define _HYPERV_HID_PROTOCOL_H_


#include <hyperv_spec.h>


#define HV_HID_RING_SIZE                                        0x8000
#define HV_HID_RX_PKT_BUFFER_SIZE                       256
#define HV_HID_REQUEST_TRANS_ID                         0xCAFECAFE
#define HV_HID_TIMEOUT_US                                       HV_MS_TO_US(5000)


typedef struct {
        uint8   length;
        uint8   type;
        uint16  version;
        uint8   country_code;
        uint8   num_descriptors;
        uint8   hid_descriptor_type;
        uint16  hid_descriptor_length;
} _PACKED hv_hid_descriptor;


typedef struct {
        uint32  length;
        uint16  vendor_id;
        uint16  product_id;
        uint16  version;
        uint16  reserved[11];
} _PACKED hv_hid_dev_info;


// Hyper-V HID version
#define MAKE_HID_VERSION(major, minor)  ((((major) << 16) & 0xFFFF0000) | ((minor) & 0x0000FFFF))
#define GET_HID_VERSION_MAJOR(version)  (((version) >> 16) & 0xFFFF)
#define GET_HID_VERSION_MINOR(version)  ((version) & 0xFFFF)

// HID protocol version 2.0 used in Server 2008 and newer.
#define HV_HID_VERSION_V2_0                             MAKE_HID_VERSION(2, 0)


// HID pipe message types
enum {
        HV_HID_PIPE_MSGTYPE_INVALID             = 0,
        HV_HID_PIPE_MSGTYPE_DATA                = 1
};


// HID message types
enum {
        HV_HID_MSGTYPE_PROTOCOL_REQUEST                 = 0,
        HV_HID_MSGTYPE_PROTOCOL_RESPONSE                = 1,
        HV_HID_MSGTYPE_INITIAL_DEV_INFO                 = 2,
        HV_HID_MSGTYPE_INITIAL_DEV_INFO_ACK             = 3,
        HV_HID_MSGTYPE_INPUT_REPORT                             = 4,
        HV_HID_MSGTYPE_INPUT_MAX
};


// HID message header
typedef struct {
        uint32  type;
        uint32  length;
} _PACKED hv_hid_msg_header;


// HID protocol request message sent to Hyper-V
typedef struct {
        hv_hid_msg_header       header;

        uint32  version;
} _PACKED hv_hid_msg_protocol_request;


// HID protocol response message received from Hyper-V
typedef struct {
        hv_hid_msg_header       header;

        uint32  version;
        uint8   result;
        uint8   reserved[3];
} _PACKED hv_hid_msg_protocol_response;


// HID initial device info message received from Hyper-V
typedef struct {
        hv_hid_msg_header       header;

        hv_hid_dev_info         info;
        hv_hid_descriptor       descriptor;
        uint8                           descriptor_data[];
} _PACKED hv_hid_msg_initial_dev_info;


// HID initial device info acknowledgement message sent to Hyper-V
typedef struct {
        hv_hid_msg_header       header;

        uint8   reserved;
} _PACKED hv_hid_msg_initial_dev_info_ack;


// HID input report message received from Hyper-V
typedef struct {
        hv_hid_msg_header       header;

        uint8   data[];
} _PACKED hv_hid_msg_input_report;


// HID pipe message header
typedef struct {
        uint32  type;
        uint32  length;
} _PACKED hv_hid_pipe_msg_header;


// HID pipe message sent to Hyper-V
typedef struct {
        hv_hid_pipe_msg_header  pipe_header;

        union {
                hv_hid_msg_header                                       header;
                hv_hid_msg_protocol_request                     protocol_req;
                hv_hid_msg_protocol_response            protocol_resp;
                hv_hid_msg_initial_dev_info_ack         dev_info_ack;
        };
} _PACKED hv_hid_pipe_out_msg;


// HID pipe message received from Hyper-V
typedef struct {
        hv_hid_pipe_msg_header  pipe_header;

        union {
                hv_hid_msg_header                                       header;
                hv_hid_msg_protocol_request                     protocol_req;
                hv_hid_msg_protocol_response            protocol_resp;
                hv_hid_msg_initial_dev_info                     dev_info;
                hv_hid_msg_initial_dev_info_ack         dev_info_ack;
                hv_hid_msg_input_report                         input_report;
        };
} _PACKED hv_hid_pipe_in_msg;


typedef struct {
        uint8   buttons;
        uint16  x;
        uint16  y;
        int8    wheel;
} _PACKED hyperv_hid_input_report;


#endif // _HYPERV_HID_PROTOCOL_H_