libusb.h

/*
 * Public libusb header file
 * Copyright (C) 2007-2008 Daniel Drake <dsd@gentoo.org>
 * Copyright (c) 2001 Johannes Erdfelt <johannes@erdfelt.com>
 * Copyright (C) 2012 Nathan Hjelm <hjelmn@cs.unm.edu>
 * Copyright (C) 2012 Peter Stuge <peter@stuge.se>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#ifndef LIBUSB_H
#define LIBUSB_H

#ifdef _MSC_VER
/* on MS environments, the inline keyword is available in C++ only */
#define inline __inline
/* ssize_t is also not available (copy/paste from MinGW) */
#ifndef _SSIZE_T_DEFINED
#define _SSIZE_T_DEFINED
#undef ssize_t
#ifdef _WIN64
  typedef __int64 ssize_t;
#else
  typedef int ssize_t;
#endif /* _WIN64 */
#endif /* _SSIZE_T_DEFINED */
#endif /* _MSC_VER */

/* stdint.h is also not usually available on MS */
#if defined(_MSC_VER) && (_MSC_VER < 1600) && (!defined(_STDINT)) && (!defined(_STDINT_H))
typedef unsigned __int8   uint8_t;
typedef unsigned __int16  uint16_t;
typedef unsigned __int32  uint32_t;
#else
#include <stdint.h>
#endif

#include <sys/types.h>
#include <time.h>
#include <limits.h>

#if defined(__linux) || defined(__APPLE__) || defined(__CYGWIN__)
#include <sys/time.h>
#endif

/* 'interface' might be defined as a macro on Windows, so we need to
 * undefine it so as not to break the current libusb API, because
 * libusb_config_descriptor has an 'interface' member
 * As this can be problematic if you include windows.h after libusb.h
 * in your sources, we force windows.h to be included first. */
#if defined(_WIN32) || defined(__CYGWIN__)
#include <windows.h>
#if defined(interface)
#undef interface
#endif
#endif

/* LIBUSB_CALL must be defined on both definition and declaration of libusb
 * functions. You'd think that declaration would be enough, but cygwin will
 * complain about conflicting types unless both are marked this way.
 * The placement of this macro is important too; it must appear after the
 * return type, before the function name. See internal documentation for
 * API_EXPORTED.
 */
#if defined(_WIN32) || defined(__CYGWIN__)
#define LIBUSB_CALL WINAPI
#else
#define LIBUSB_CALL
#endif

#ifdef __cplusplus
extern "C" {
#endif

static inline uint16_t libusb_cpu_to_le16(const uint16_t x)
{
    union {
        uint8_t  b8[2];
        uint16_t b16;
    } _tmp;
    _tmp.b8[1] = x >> 8;
    _tmp.b8[0] = x & 0xff;
    return _tmp.b16;
}

#define libusb_le16_to_cpu libusb_cpu_to_le16

/* standard USB stuff */

enum libusb_class_code {
    LIBUSB_CLASS_PER_INTERFACE = 0,

    LIBUSB_CLASS_AUDIO = 1,

    LIBUSB_CLASS_COMM = 2,

    LIBUSB_CLASS_HID = 3,

    LIBUSB_CLASS_PHYSICAL = 5,

    LIBUSB_CLASS_PRINTER = 7,

    LIBUSB_CLASS_PTP = 6, /* legacy name from libusb-0.1 usb.h */
    LIBUSB_CLASS_IMAGE = 6,

    LIBUSB_CLASS_MASS_STORAGE = 8,

    LIBUSB_CLASS_HUB = 9,

    LIBUSB_CLASS_DATA = 10,

    LIBUSB_CLASS_SMART_CARD = 0x0b,

    LIBUSB_CLASS_CONTENT_SECURITY = 0x0d,

    LIBUSB_CLASS_VIDEO = 0x0e,

    LIBUSB_CLASS_PERSONAL_HEALTHCARE = 0x0f,

    LIBUSB_CLASS_DIAGNOSTIC_DEVICE = 0xdc,

    LIBUSB_CLASS_WIRELESS = 0xe0,

    LIBUSB_CLASS_APPLICATION = 0xfe,

    LIBUSB_CLASS_VENDOR_SPEC = 0xff
};

enum libusb_descriptor_type {
    LIBUSB_DT_DEVICE = 0x01,

    LIBUSB_DT_CONFIG = 0x02,

    LIBUSB_DT_STRING = 0x03,

    LIBUSB_DT_INTERFACE = 0x04,

    LIBUSB_DT_ENDPOINT = 0x05,

    LIBUSB_DT_HID = 0x21,

    LIBUSB_DT_REPORT = 0x22,

    LIBUSB_DT_PHYSICAL = 0x23,

    LIBUSB_DT_HUB = 0x29,
};

/* Descriptor sizes per descriptor type */
#define LIBUSB_DT_DEVICE_SIZE           18
#define LIBUSB_DT_CONFIG_SIZE           9
#define LIBUSB_DT_INTERFACE_SIZE        9
#define LIBUSB_DT_ENDPOINT_SIZE     7
#define LIBUSB_DT_ENDPOINT_AUDIO_SIZE   9   /* Audio extension */
#define LIBUSB_DT_HUB_NONVAR_SIZE       7

#define LIBUSB_ENDPOINT_ADDRESS_MASK    0x0f    /* in bEndpointAddress */
#define LIBUSB_ENDPOINT_DIR_MASK        0x80

enum libusb_endpoint_direction {
    LIBUSB_ENDPOINT_IN = 0x80,

    LIBUSB_ENDPOINT_OUT = 0x00
};

#define LIBUSB_TRANSFER_TYPE_MASK           0x03    /* in bmAttributes */

enum libusb_transfer_type {
    LIBUSB_TRANSFER_TYPE_CONTROL = 0,

    LIBUSB_TRANSFER_TYPE_ISOCHRONOUS = 1,

    LIBUSB_TRANSFER_TYPE_BULK = 2,

    LIBUSB_TRANSFER_TYPE_INTERRUPT = 3
};

enum libusb_standard_request {
    LIBUSB_REQUEST_GET_STATUS = 0x00,

    LIBUSB_REQUEST_CLEAR_FEATURE = 0x01,

    /* 0x02 is reserved */

    LIBUSB_REQUEST_SET_FEATURE = 0x03,

    /* 0x04 is reserved */

    LIBUSB_REQUEST_SET_ADDRESS = 0x05,

    LIBUSB_REQUEST_GET_DESCRIPTOR = 0x06,

    LIBUSB_REQUEST_SET_DESCRIPTOR = 0x07,

    LIBUSB_REQUEST_GET_CONFIGURATION = 0x08,

    LIBUSB_REQUEST_SET_CONFIGURATION = 0x09,

    LIBUSB_REQUEST_GET_INTERFACE = 0x0A,

    LIBUSB_REQUEST_SET_INTERFACE = 0x0B,

    LIBUSB_REQUEST_SYNCH_FRAME = 0x0C,
};

enum libusb_request_type {
    LIBUSB_REQUEST_TYPE_STANDARD = (0x00 << 5),

    LIBUSB_REQUEST_TYPE_CLASS = (0x01 << 5),

    LIBUSB_REQUEST_TYPE_VENDOR = (0x02 << 5),

    LIBUSB_REQUEST_TYPE_RESERVED = (0x03 << 5)
};

enum libusb_request_recipient {
    LIBUSB_RECIPIENT_DEVICE = 0x00,

    LIBUSB_RECIPIENT_INTERFACE = 0x01,

    LIBUSB_RECIPIENT_ENDPOINT = 0x02,

    LIBUSB_RECIPIENT_OTHER = 0x03,
};

#define LIBUSB_ISO_SYNC_TYPE_MASK       0x0C

enum libusb_iso_sync_type {
    LIBUSB_ISO_SYNC_TYPE_NONE = 0,

    LIBUSB_ISO_SYNC_TYPE_ASYNC = 1,

    LIBUSB_ISO_SYNC_TYPE_ADAPTIVE = 2,

    LIBUSB_ISO_SYNC_TYPE_SYNC = 3
};

#define LIBUSB_ISO_USAGE_TYPE_MASK 0x30

enum libusb_iso_usage_type {
    LIBUSB_ISO_USAGE_TYPE_DATA = 0,

    LIBUSB_ISO_USAGE_TYPE_FEEDBACK = 1,

    LIBUSB_ISO_USAGE_TYPE_IMPLICIT = 2,
};

struct libusb_device_descriptor {
    uint8_t  bLength;

    uint8_t  bDescriptorType;

    uint16_t bcdUSB;

    uint8_t  bDeviceClass;

    uint8_t  bDeviceSubClass;

    uint8_t  bDeviceProtocol;

    uint8_t  bMaxPacketSize0;

    uint16_t idVendor;

    uint16_t idProduct;

    uint16_t bcdDevice;

    uint8_t  iManufacturer;

    uint8_t  iProduct;

    uint8_t  iSerialNumber;

    uint8_t  bNumConfigurations;
};

struct libusb_endpoint_descriptor {
    uint8_t  bLength;

    uint8_t  bDescriptorType;

    uint8_t  bEndpointAddress;

    uint8_t  bmAttributes;

    uint16_t wMaxPacketSize;

    uint8_t  bInterval;

    uint8_t  bRefresh;

    uint8_t  bSynchAddress;

    const unsigned char *extra;

    int extra_length;
};

struct libusb_interface_descriptor {
    uint8_t  bLength;

    uint8_t  bDescriptorType;

    uint8_t  bInterfaceNumber;

    uint8_t  bAlternateSetting;

    uint8_t  bNumEndpoints;

    uint8_t  bInterfaceClass;

    uint8_t  bInterfaceSubClass;

    uint8_t  bInterfaceProtocol;

    uint8_t  iInterface;

    const struct libusb_endpoint_descriptor *endpoint;

    const unsigned char *extra;

    int extra_length;
};

struct libusb_interface {
    const struct libusb_interface_descriptor *altsetting;

    int num_altsetting;
};

struct libusb_config_descriptor {
    uint8_t  bLength;

    uint8_t  bDescriptorType;

    uint16_t wTotalLength;

    uint8_t  bNumInterfaces;

    uint8_t  bConfigurationValue;

    uint8_t  iConfiguration;

    uint8_t  bmAttributes;

    uint8_t  MaxPower;

    const struct libusb_interface *interface;

    const unsigned char *extra;

    int extra_length;
};

struct libusb_control_setup {
    uint8_t  bmRequestType;

    uint8_t  bRequest;

    uint16_t wValue;

    uint16_t wIndex;

    uint16_t wLength;
};

#define LIBUSB_CONTROL_SETUP_SIZE (sizeof(struct libusb_control_setup))

/* libusb */

struct libusb_context;
struct libusb_device;
struct libusb_device_handle;

struct libusb_version {
    const uint16_t major;

    const uint16_t minor;

    const uint16_t micro;

    const uint16_t nano;

    const char *rc;

    const char *describe;
};

typedef struct libusb_context libusb_context;

typedef struct libusb_device libusb_device;


typedef struct libusb_device_handle libusb_device_handle;

enum libusb_speed {
    LIBUSB_SPEED_UNKNOWN = 0,

    LIBUSB_SPEED_LOW = 1,

    LIBUSB_SPEED_FULL = 2,

    LIBUSB_SPEED_HIGH = 3,

    LIBUSB_SPEED_SUPER = 4,
};

enum libusb_error {
    LIBUSB_SUCCESS = 0,

    LIBUSB_ERROR_IO = -1,

    LIBUSB_ERROR_INVALID_PARAM = -2,

    LIBUSB_ERROR_ACCESS = -3,

    LIBUSB_ERROR_NO_DEVICE = -4,

    LIBUSB_ERROR_NOT_FOUND = -5,

    LIBUSB_ERROR_BUSY = -6,

    LIBUSB_ERROR_TIMEOUT = -7,

    LIBUSB_ERROR_OVERFLOW = -8,

    LIBUSB_ERROR_PIPE = -9,

    LIBUSB_ERROR_INTERRUPTED = -10,

    LIBUSB_ERROR_NO_MEM = -11,

    LIBUSB_ERROR_NOT_SUPPORTED = -12,

    /* NB! Remember to update libusb_error_name()
       when adding new error codes here. */

    LIBUSB_ERROR_OTHER = -99,
};

enum libusb_transfer_status {
    LIBUSB_TRANSFER_COMPLETED,

    LIBUSB_TRANSFER_ERROR,

    LIBUSB_TRANSFER_TIMED_OUT,

    LIBUSB_TRANSFER_CANCELLED,

    LIBUSB_TRANSFER_STALL,

    LIBUSB_TRANSFER_NO_DEVICE,

    LIBUSB_TRANSFER_OVERFLOW,
};

enum libusb_transfer_flags {
    LIBUSB_TRANSFER_SHORT_NOT_OK = 1<<0,

    LIBUSB_TRANSFER_FREE_BUFFER = 1<<1,

    LIBUSB_TRANSFER_FREE_TRANSFER = 1<<2,

    LIBUSB_TRANSFER_ADD_ZERO_PACKET = 1 << 3,
};

struct libusb_iso_packet_descriptor {
    unsigned int length;

    unsigned int actual_length;

    enum libusb_transfer_status status;
};

struct libusb_transfer;

typedef void (LIBUSB_CALL *libusb_transfer_cb_fn)(struct libusb_transfer *transfer);

struct libusb_transfer {
    libusb_device_handle *dev_handle;

    uint8_t flags;

    unsigned char endpoint;

    unsigned char type;

    unsigned int timeout;

    enum libusb_transfer_status status;

    int length;

    int actual_length;

    libusb_transfer_cb_fn callback;

    void *user_data;

    unsigned char *buffer;

    int num_iso_packets;

    struct libusb_iso_packet_descriptor iso_packet_desc
#if defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L)
    [] /* valid C99 code */
#else
    [0] /* non-standard, but usually working code */
#endif
    ;
};

enum libusb_capability {
    LIBUSB_CAP_HAS_CAPABILITY = 0,
    LIBUSB_CAP_HAS_HOTPLUG    = 1,
};

int LIBUSB_CALL libusb_init(libusb_context **ctx);
void LIBUSB_CALL libusb_exit(libusb_context *ctx);
void LIBUSB_CALL libusb_set_debug(libusb_context *ctx, int level);
const struct libusb_version * LIBUSB_CALL libusb_get_version(void);
int LIBUSB_CALL libusb_has_capability(uint32_t capability);
const char * LIBUSB_CALL libusb_error_name(int errcode);

ssize_t LIBUSB_CALL libusb_get_device_list(libusb_context *ctx,
    libusb_device ***list);
void LIBUSB_CALL libusb_free_device_list(libusb_device **list,
    int unref_devices);
libusb_device * LIBUSB_CALL libusb_ref_device(libusb_device *dev);
void LIBUSB_CALL libusb_unref_device(libusb_device *dev);

int LIBUSB_CALL libusb_get_configuration(libusb_device_handle *dev,
    int *config);
int LIBUSB_CALL libusb_get_device_descriptor(libusb_device *dev,
    struct libusb_device_descriptor *desc);
int LIBUSB_CALL libusb_get_active_config_descriptor(libusb_device *dev,
    struct libusb_config_descriptor **config);
int LIBUSB_CALL libusb_get_config_descriptor(libusb_device *dev,
    uint8_t config_index, struct libusb_config_descriptor **config);
int LIBUSB_CALL libusb_get_config_descriptor_by_value(libusb_device *dev,
    uint8_t bConfigurationValue, struct libusb_config_descriptor **config);
void LIBUSB_CALL libusb_free_config_descriptor(
    struct libusb_config_descriptor *config);
uint8_t LIBUSB_CALL libusb_get_bus_number(libusb_device *dev);
uint8_t LIBUSB_CALL libusb_get_device_address(libusb_device *dev);
int LIBUSB_CALL libusb_get_device_speed(libusb_device *dev);
int LIBUSB_CALL libusb_get_max_packet_size(libusb_device *dev,
    unsigned char endpoint);
int LIBUSB_CALL libusb_get_max_iso_packet_size(libusb_device *dev,
    unsigned char endpoint);

int LIBUSB_CALL libusb_open(libusb_device *dev, libusb_device_handle **handle);
void LIBUSB_CALL libusb_close(libusb_device_handle *dev_handle);
libusb_device * LIBUSB_CALL libusb_get_device(libusb_device_handle *dev_handle);

int LIBUSB_CALL libusb_set_configuration(libusb_device_handle *dev,
    int configuration);
int LIBUSB_CALL libusb_claim_interface(libusb_device_handle *dev,
    int interface_number);
int LIBUSB_CALL libusb_release_interface(libusb_device_handle *dev,
    int interface_number);

libusb_device_handle * LIBUSB_CALL libusb_open_device_with_vid_pid(
    libusb_context *ctx, uint16_t vendor_id, uint16_t product_id);

int LIBUSB_CALL libusb_set_interface_alt_setting(libusb_device_handle *dev,
    int interface_number, int alternate_setting);
int LIBUSB_CALL libusb_clear_halt(libusb_device_handle *dev,
    unsigned char endpoint);
int LIBUSB_CALL libusb_reset_device(libusb_device_handle *dev);

int LIBUSB_CALL libusb_kernel_driver_active(libusb_device_handle *dev,
    int interface_number);
int LIBUSB_CALL libusb_detach_kernel_driver(libusb_device_handle *dev,
    int interface_number);
int LIBUSB_CALL libusb_attach_kernel_driver(libusb_device_handle *dev,
    int interface_number);

/* async I/O */

static inline unsigned char *libusb_control_transfer_get_data(
    struct libusb_transfer *transfer)
{
    return transfer->buffer + LIBUSB_CONTROL_SETUP_SIZE;
}

static inline struct libusb_control_setup *libusb_control_transfer_get_setup(
    struct libusb_transfer *transfer)
{
    return (struct libusb_control_setup *) transfer->buffer;
}

static inline void libusb_fill_control_setup(unsigned char *buffer,
    uint8_t bmRequestType, uint8_t bRequest, uint16_t wValue, uint16_t wIndex,
    uint16_t wLength)
{
    struct libusb_control_setup *setup = (struct libusb_control_setup *) buffer;
    setup->bmRequestType = bmRequestType;
    setup->bRequest = bRequest;
    setup->wValue = libusb_cpu_to_le16(wValue);
    setup->wIndex = libusb_cpu_to_le16(wIndex);
    setup->wLength = libusb_cpu_to_le16(wLength);
}

struct libusb_transfer * LIBUSB_CALL libusb_alloc_transfer(int iso_packets);
int LIBUSB_CALL libusb_submit_transfer(struct libusb_transfer *transfer);
int LIBUSB_CALL libusb_cancel_transfer(struct libusb_transfer *transfer);
void LIBUSB_CALL libusb_free_transfer(struct libusb_transfer *transfer);

static inline void libusb_fill_control_transfer(
    struct libusb_transfer *transfer, libusb_device_handle *dev_handle,
    unsigned char *buffer, libusb_transfer_cb_fn callback, void *user_data,
    unsigned int timeout)
{
    struct libusb_control_setup *setup = (struct libusb_control_setup *) buffer;
    transfer->dev_handle = dev_handle;
    transfer->endpoint = 0;
    transfer->type = LIBUSB_TRANSFER_TYPE_CONTROL;
    transfer->timeout = timeout;
    transfer->buffer = buffer;
    if (setup)
        transfer->length = LIBUSB_CONTROL_SETUP_SIZE
            + libusb_le16_to_cpu(setup->wLength);
    transfer->user_data = user_data;
    transfer->callback = callback;
}

static inline void libusb_fill_bulk_transfer(struct libusb_transfer *transfer,
    libusb_device_handle *dev_handle, unsigned char endpoint,
    unsigned char *buffer, int length, libusb_transfer_cb_fn callback,
    void *user_data, unsigned int timeout)
{
    transfer->dev_handle = dev_handle;
    transfer->endpoint = endpoint;
    transfer->type = LIBUSB_TRANSFER_TYPE_BULK;
    transfer->timeout = timeout;
    transfer->buffer = buffer;
    transfer->length = length;
    transfer->user_data = user_data;
    transfer->callback = callback;
}

static inline void libusb_fill_interrupt_transfer(
    struct libusb_transfer *transfer, libusb_device_handle *dev_handle,
    unsigned char endpoint, unsigned char *buffer, int length,
    libusb_transfer_cb_fn callback, void *user_data, unsigned int timeout)
{
    transfer->dev_handle = dev_handle;
    transfer->endpoint = endpoint;
    transfer->type = LIBUSB_TRANSFER_TYPE_INTERRUPT;
    transfer->timeout = timeout;
    transfer->buffer = buffer;
    transfer->length = length;
    transfer->user_data = user_data;
    transfer->callback = callback;
}

static inline void libusb_fill_iso_transfer(struct libusb_transfer *transfer,
    libusb_device_handle *dev_handle, unsigned char endpoint,
    unsigned char *buffer, int length, int num_iso_packets,
    libusb_transfer_cb_fn callback, void *user_data, unsigned int timeout)
{
    transfer->dev_handle = dev_handle;
    transfer->endpoint = endpoint;
    transfer->type = LIBUSB_TRANSFER_TYPE_ISOCHRONOUS;
    transfer->timeout = timeout;
    transfer->buffer = buffer;
    transfer->length = length;
    transfer->num_iso_packets = num_iso_packets;
    transfer->user_data = user_data;
    transfer->callback = callback;
}

static inline void libusb_set_iso_packet_lengths(
    struct libusb_transfer *transfer, unsigned int length)
{
    int i;
    for (i = 0; i < transfer->num_iso_packets; i++)
        transfer->iso_packet_desc[i].length = length;
}

static inline unsigned char *libusb_get_iso_packet_buffer(
    struct libusb_transfer *transfer, unsigned int packet)
{
    int i;
    size_t offset = 0;
    int _packet;

    /* oops..slight bug in the API. packet is an unsigned int, but we use
     * signed integers almost everywhere else. range-check and convert to
     * signed to avoid compiler warnings. FIXME for libusb-2. */
    if (packet > INT_MAX)
        return NULL;
    _packet = packet;

    if (_packet >= transfer->num_iso_packets)
        return NULL;

    for (i = 0; i < _packet; i++)
        offset += transfer->iso_packet_desc[i].length;

    return transfer->buffer + offset;
}

static inline unsigned char *libusb_get_iso_packet_buffer_simple(
    struct libusb_transfer *transfer, unsigned int packet)
{
    int _packet;

    /* oops..slight bug in the API. packet is an unsigned int, but we use
     * signed integers almost everywhere else. range-check and convert to
     * signed to avoid compiler warnings. FIXME for libusb-2. */
    if (packet > INT_MAX)
        return NULL;
    _packet = packet;

    if (_packet >= transfer->num_iso_packets)
        return NULL;

    return transfer->buffer + (transfer->iso_packet_desc[0].length * _packet);
}

/* sync I/O */

int LIBUSB_CALL libusb_control_transfer(libusb_device_handle *dev_handle,
    uint8_t request_type, uint8_t bRequest, uint16_t wValue, uint16_t wIndex,
    unsigned char *data, uint16_t wLength, unsigned int timeout);

int LIBUSB_CALL libusb_bulk_transfer(libusb_device_handle *dev_handle,
    unsigned char endpoint, unsigned char *data, int length,
    int *actual_length, unsigned int timeout);

int LIBUSB_CALL libusb_interrupt_transfer(libusb_device_handle *dev_handle,
    unsigned char endpoint, unsigned char *data, int length,
    int *actual_length, unsigned int timeout);

static inline int libusb_get_descriptor(libusb_device_handle *dev,
    uint8_t desc_type, uint8_t desc_index, unsigned char *data, int length)
{
    return libusb_control_transfer(dev, LIBUSB_ENDPOINT_IN,
        LIBUSB_REQUEST_GET_DESCRIPTOR, (desc_type << 8) | desc_index, 0, data,
        (uint16_t) length, 1000);
}

static inline int libusb_get_string_descriptor(libusb_device_handle *dev,
    uint8_t desc_index, uint16_t langid, unsigned char *data, int length)
{
    return libusb_control_transfer(dev, LIBUSB_ENDPOINT_IN,
        LIBUSB_REQUEST_GET_DESCRIPTOR, (uint16_t)((LIBUSB_DT_STRING << 8) | desc_index),
        langid, data, (uint16_t) length, 1000);
}

int LIBUSB_CALL libusb_get_string_descriptor_ascii(libusb_device_handle *dev,
    uint8_t desc_index, unsigned char *data, int length);

/* polling and timeouts */

int LIBUSB_CALL libusb_try_lock_events(libusb_context *ctx);
void LIBUSB_CALL libusb_lock_events(libusb_context *ctx);
void LIBUSB_CALL libusb_unlock_events(libusb_context *ctx);
int LIBUSB_CALL libusb_event_handling_ok(libusb_context *ctx);
int LIBUSB_CALL libusb_event_handler_active(libusb_context *ctx);
void LIBUSB_CALL libusb_lock_event_waiters(libusb_context *ctx);
void LIBUSB_CALL libusb_unlock_event_waiters(libusb_context *ctx);
int LIBUSB_CALL libusb_wait_for_event(libusb_context *ctx, struct timeval *tv);

int LIBUSB_CALL libusb_handle_events_timeout(libusb_context *ctx,
    struct timeval *tv);
int LIBUSB_CALL libusb_handle_events_timeout_completed(libusb_context *ctx,
    struct timeval *tv, int *completed);
int LIBUSB_CALL libusb_handle_events(libusb_context *ctx);
int LIBUSB_CALL libusb_handle_events_completed(libusb_context *ctx, int *completed);
int LIBUSB_CALL libusb_handle_events_locked(libusb_context *ctx,
    struct timeval *tv);
int LIBUSB_CALL libusb_pollfds_handle_timeouts(libusb_context *ctx);
int LIBUSB_CALL libusb_get_next_timeout(libusb_context *ctx,
    struct timeval *tv);

struct libusb_pollfd {
    int fd;

    short events;
};

typedef void (LIBUSB_CALL *libusb_pollfd_added_cb)(int fd, short events,
    void *user_data);

typedef void (LIBUSB_CALL *libusb_pollfd_removed_cb)(int fd, void *user_data);

const struct libusb_pollfd ** LIBUSB_CALL libusb_get_pollfds(
    libusb_context *ctx);
void LIBUSB_CALL libusb_set_pollfd_notifiers(libusb_context *ctx,
    libusb_pollfd_added_cb added_cb, libusb_pollfd_removed_cb removed_cb,
    void *user_data);

typedef enum {
    LIBUSB_HOTPLUG_PERSIST   = 0,

    LIBUSB_HOTPLUG_ONCE      = 1,
} libusb_hotplug_flag;

typedef enum {
    LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED = 0x01,

    LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT    = 0x02,
} libusb_hotplug_event;

enum {
    LIBUSB_HOTPLUG_CLASS_ANY     = -1,

    LIBUSB_HOTPLUG_VENDORID_ANY  = -2,

    LIBUSB_HOTPLUG_PRODUCTID_ANY = -3,
};

typedef void (LIBUSB_CALL *libusb_hotplug_callback_fn)(libusb_context *ctx,
                               libusb_device *device,
                               libusb_hotplug_event event,
                               void *user_data);

struct libusb_hotplug_callback {
    struct libusb_context *ctx;

    int vendor_id;

    int product_id;

    int dev_class;

        libusb_hotplug_flag flags;

    libusb_hotplug_event event;

    libusb_hotplug_callback_fn cb;

    void *user_data;

    char reserved[32];
};

typedef struct libusb_hotplug_callback libusb_hotplug_callback;

static inline void libusb_hotplug_prepare_callback(libusb_hotplug_callback *cb,
                           libusb_context *ctx,
                           libusb_hotplug_event event,
                           libusb_hotplug_flag flags,
                           int vendor_id, int product_id,
                           int dev_class,
                           libusb_hotplug_callback_fn cb_fn,
                           void *user_data)
{
    cb->ctx        = ctx;
    cb->vendor_id  = vendor_id;
    cb->product_id = product_id;
    cb->dev_class  = dev_class;
    cb->flags      = flags;
    cb->cb         = cb_fn;
    cb->user_data  = user_data;
    cb->event      = event;
}

void LIBUSB_CALL libusb_hotplug_register_callback(libusb_hotplug_callback *cb);

void LIBUSB_CALL libusb_hotplug_deregister_callback(libusb_hotplug_callback *cb);

#ifdef __cplusplus
}
#endif

#endif