text: /*
   * This file is part of the Micro Python project, http://micropython.org/
   *
   * The MIT License (MIT)
   *
   * Copyright (c) 2013, 2014, 2015 Damien P. George
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to deal
   * in the Software without restriction, including without limitation the rights
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   * THE SOFTWARE.
   */
  
  #include <stdarg.h>
  #include <string.h>
  
  #include "usbd_core.h"
  #include "usbd_desc.h"
  #include "usbd_cdc_msc_hid.h"
  #include "usbd_cdc_interface.h"
  #include "usbd_msc_storage.h"
  
  #include "py/objstr.h"
  #include "py/runtime.h"
  #include "py/stream.h"
  #include "py/mperrno.h"
  #include "bufhelper.h"
  #include "usb.h"
  #include "pybioctl.h"
  
  #if defined(USE_USB_FS)
  #define USB_PHY_ID  USB_PHY_FS_ID
  #elif defined(USE_USB_HS) && defined(USE_USB_HS_IN_FS)
  #define USB_PHY_ID  USB_PHY_HS_ID
  #else
  #error Unable to determine proper USB_PHY_ID to use
  #endif
  
  // this will be persistent across a soft-reset
  mp_uint_t pyb_usb_flags = 0;
  
  #ifdef USE_DEVICE_MODE
  USBD_HandleTypeDef hUSBDDevice;
  pyb_usb_storage_medium_t pyb_usb_storage_medium = PYB_USB_STORAGE_MEDIUM_NONE;
  #endif
  
  // predefined hid mouse data
  STATIC const mp_obj_str_t pyb_usb_hid_mouse_desc_obj = {
      {&mp_type_bytes},
      0, // hash not valid
      USBD_HID_MOUSE_REPORT_DESC_SIZE,
      USBD_HID_MOUSE_ReportDesc,
  };
  const mp_obj_tuple_t pyb_usb_hid_mouse_obj = {
      {&mp_type_tuple},
      5,
      {
          MP_OBJ_NEW_SMALL_INT(1), // subclass: boot
          MP_OBJ_NEW_SMALL_INT(2), // protocol: mouse
          MP_OBJ_NEW_SMALL_INT(USBD_HID_MOUSE_MAX_PACKET),
          MP_OBJ_NEW_SMALL_INT(8), // polling interval: 8ms
          (mp_obj_t)&pyb_usb_hid_mouse_desc_obj,
      },
  };
  
  // predefined hid keyboard data
  STATIC const mp_obj_str_t pyb_usb_hid_keyboard_desc_obj = {
      {&mp_type_bytes},
      0, // hash not valid
      USBD_HID_KEYBOARD_REPORT_DESC_SIZE,
      USBD_HID_KEYBOARD_ReportDesc,
  };
  const mp_obj_tuple_t pyb_usb_hid_keyboard_obj = {
      {&mp_type_tuple},
      5,
      {
          MP_OBJ_NEW_SMALL_INT(1), // subclass: boot
          MP_OBJ_NEW_SMALL_INT(1), // protocol: keyboard
          MP_OBJ_NEW_SMALL_INT(USBD_HID_KEYBOARD_MAX_PACKET),
          MP_OBJ_NEW_SMALL_INT(8), // polling interval: 8ms
          (mp_obj_t)&pyb_usb_hid_keyboard_desc_obj,
      },
  };
  
  void pyb_usb_init0(void) {
      // create an exception object for interrupting by VCP
      MP_STATE_PORT(mp_const_vcp_interrupt) = mp_obj_new_exception(&mp_type_KeyboardInterrupt);
      USBD_CDC_SetInterrupt(-1, MP_STATE_PORT(mp_const_vcp_interrupt));
      MP_STATE_PORT(pyb_hid_report_desc) = MP_OBJ_NULL;
  }
  
  bool pyb_usb_dev_init(uint16_t vid, uint16_t pid, usb_device_mode_t mode, USBD_HID_ModeInfoTypeDef *hid_info) {
  #ifdef USE_DEVICE_MODE
      if (!(pyb_usb_flags & PYB_USB_FLAG_DEV_ENABLED)) {
          // only init USB once in the device's power-lifetime
          USBD_SetVIDPIDRelease(vid, pid, 0x0200, mode == USBD_MODE_CDC);
          if (USBD_SelectMode(mode, hid_info) != 0) {
              return false;
          }
          USBD_Init(&hUSBDDevice, (USBD_DescriptorsTypeDef*)&USBD_Descriptors, USB_PHY_ID);
          USBD_RegisterClass(&hUSBDDevice, &USBD_CDC_MSC_HID);
          USBD_CDC_RegisterInterface(&hUSBDDevice, (USBD_CDC_ItfTypeDef*)&USBD_CDC_fops);
          switch (pyb_usb_storage_medium) {
  #if MICROPY_HW_HAS_SDCARD
              case PYB_USB_STORAGE_MEDIUM_SDCARD:
                  USBD_MSC_RegisterStorage(&hUSBDDevice, (USBD_StorageTypeDef*)&USBD_SDCARD_STORAGE_fops);
                  break;
  #endif
              default:
                  USBD_MSC_RegisterStorage(&hUSBDDevice, (USBD_StorageTypeDef*)&USBD_FLASH_STORAGE_fops);
                  break;
          }
          USBD_Start(&hUSBDDevice);
      }
      pyb_usb_flags |= PYB_USB_FLAG_DEV_ENABLED;
  #endif
  
      return true;
  }
  
  void pyb_usb_dev_deinit(void) {
      if (pyb_usb_flags & PYB_USB_FLAG_DEV_ENABLED) {
          USBD_Stop(&hUSBDDevice);
          pyb_usb_flags &= ~PYB_USB_FLAG_DEV_ENABLED;
      }
  }
  
  bool usb_vcp_is_enabled(void) {
      return (pyb_usb_flags & PYB_USB_FLAG_DEV_ENABLED) != 0;
  }
  
  void usb_vcp_set_interrupt_char(int c) {
      if (pyb_usb_flags & PYB_USB_FLAG_DEV_ENABLED) {
          if (c != -1) {
              mp_obj_exception_clear_traceback(MP_STATE_PORT(mp_const_vcp_interrupt));
          }
          USBD_CDC_SetInterrupt(c, MP_STATE_PORT(mp_const_vcp_interrupt));
      }
  }
  
  int usb_vcp_recv_byte(uint8_t *c) {
      return USBD_CDC_Rx(c, 1, 0);
  }
  
  void usb_vcp_send_strn(const char *str, int len) {
  #ifdef USE_DEVICE_MODE
      if (pyb_usb_flags & PYB_USB_FLAG_DEV_ENABLED) {
          USBD_CDC_TxAlways((const uint8_t*)str, len);
      }
  #endif
  }
  
  void usb_vcp_send_strn_cooked(const char *str, int len) {
  #ifdef USE_DEVICE_MODE
      if (pyb_usb_flags & PYB_USB_FLAG_DEV_ENABLED) {
          for (const char *top = str + len; str < top; str++) {
              if (*str == '\n') {
                  USBD_CDC_TxAlways((const uint8_t*)"\r\n", 2);
              } else {
                  USBD_CDC_TxAlways((const uint8_t*)str, 1);
              }
          }
      }
  #endif
  }
  
  /******************************************************************************/
  // Micro Python bindings for USB
  
  /*
    Philosophy of USB driver and Python API: pyb.usb_mode(...) configures the USB
    on the board.  The USB itself is not an entity, rather the interfaces are, and
    can be accessed by creating objects, such as pyb.USB_VCP() and pyb.USB_HID().
  
    We have:
  
      pyb.usb_mode()          # return the current usb mode
      pyb.usb_mode(None)      # disable USB
      pyb.usb_mode('VCP')     # enable with VCP interface
      pyb.usb_mode('VCP+MSC') # enable with VCP and MSC interfaces
      pyb.usb_mode('VCP+HID') # enable with VCP and HID, defaulting to mouse protocol
      pyb.usb_mode('VCP+HID', vid=0xf055, pid=0x9800) # specify VID and PID
      pyb.usb_mode('VCP+HID', hid=pyb.hid_mouse)
      pyb.usb_mode('VCP+HID', hid=pyb.hid_keyboard)
      pyb.usb_mode('VCP+HID', pid=0x1234, hid=(subclass, protocol, max_packet_len, polling_interval, report_desc))
  
      vcp = pyb.USB_VCP() # get the VCP device for read/write
      hid = pyb.USB_HID() # get the HID device for write/poll
  
    Possible extensions:
      pyb.usb_mode('host', ...)
      pyb.usb_mode('OTG', ...)
      pyb.usb_mode(..., port=2) # for second USB port
  */
  
  STATIC mp_obj_t pyb_usb_mode(mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
      static const mp_arg_t allowed_args[] = {
          { MP_QSTR_mode, MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = mp_const_none} },
          { MP_QSTR_vid, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = USBD_VID} },
          { MP_QSTR_pid, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
          { MP_QSTR_hid, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = (mp_obj_t)&pyb_usb_hid_mouse_obj} },
      };
  
      // fetch the current usb mode -> pyb.usb_mode()
      if (n_args == 0) {
      #if defined(USE_HOST_MODE)
          return MP_OBJ_NEW_QSTR(MP_QSTR_host);
      #elif defined(USE_DEVICE_MODE)
          uint8_t mode = USBD_GetMode();
          switch (mode) {
              case USBD_MODE_CDC:
                  return MP_OBJ_NEW_QSTR(MP_QSTR_VCP);
              case USBD_MODE_MSC:
                  return MP_OBJ_NEW_QSTR(MP_QSTR_MSC);
              case USBD_MODE_HID:
                  return MP_OBJ_NEW_QSTR(MP_QSTR_HID);
              case USBD_MODE_CDC_MSC:
                  return MP_OBJ_NEW_QSTR(MP_QSTR_VCP_plus_MSC);
              case USBD_MODE_CDC_HID:
                  return MP_OBJ_NEW_QSTR(MP_QSTR_VCP_plus_HID);
              case USBD_MODE_MSC_HID:
                  return MP_OBJ_NEW_QSTR(MP_QSTR_MSC_plus_HID);
              default:
                  return mp_const_none;
          }
      #endif
      }
  
      // parse args
      mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
      mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
  
      // record the fact that the usb has been explicitly configured
      pyb_usb_flags |= PYB_USB_FLAG_USB_MODE_CALLED;
  
      // check if user wants to disable the USB
      if (args[0].u_obj == mp_const_none) {
          // disable usb
          #if defined(USE_DEVICE_MODE)
          pyb_usb_dev_deinit();
          #endif
          return mp_const_none;
      }
  
      // get mode string
      const char *mode_str = mp_obj_str_get_str(args[0].u_obj);
  
  #if defined(USE_HOST_MODE)
  
      // hardware configured for USB host mode
  
      if (strcmp(mode_str, "host") == 0) {
          pyb_usb_host_init();
      } else {
          goto bad_mode;
      }
  
  #elif defined(USE_DEVICE_MODE)
  
      // hardware configured for USB device mode
  
      // get the VID, PID and USB mode
      // note: PID=-1 means select PID based on mode
      // note: we support CDC as a synonym for VCP for backward compatibility
      uint16_t vid = args[1].u_int;
      uint16_t pid = args[2].u_int;
      usb_device_mode_t mode;
      if (strcmp(mode_str, "CDC+MSC") == 0 || strcmp(mode_str, "VCP+MSC") == 0) {
          if (args[2].u_int == -1) {
              pid = USBD_PID_CDC_MSC;
          }
          mode = USBD_MODE_CDC_MSC;
      } else if (strcmp(mode_str, "CDC+HID") == 0 || strcmp(mode_str, "VCP+HID") == 0) {
          if (args[2].u_int == -1) {
              pid = USBD_PID_CDC_HID;
          }
          mode = USBD_MODE_CDC_HID;
      } else if (strcmp(mode_str, "CDC") == 0 || strcmp(mode_str, "VCP") == 0) {
          if (args[2].u_int == -1) {
              pid = USBD_PID_CDC;
          }
          mode = USBD_MODE_CDC;
      } else {
          goto bad_mode;
      }
  
      // get hid info if user selected such a mode
      USBD_HID_ModeInfoTypeDef hid_info;
      if (mode & USBD_MODE_HID) {
          mp_obj_t *items;
          mp_obj_get_array_fixed_n(args[3].u_obj, 5, &items);
          hid_info.subclass = mp_obj_get_int(items[0]);
          hid_info.protocol = mp_obj_get_int(items[1]);
          hid_info.max_packet_len = mp_obj_get_int(items[2]);
          hid_info.polling_interval = mp_obj_get_int(items[3]);
          mp_buffer_info_t bufinfo;
          mp_get_buffer_raise(items[4], &bufinfo, MP_BUFFER_READ);
          hid_info.report_desc = bufinfo.buf;
          hid_info.report_desc_len = bufinfo.len;
  
          // need to keep a copy of this so report_desc does not get GC'd
          MP_STATE_PORT(pyb_hid_report_desc) = items[4];
      }
  
      // init the USB device
      if (!pyb_usb_dev_init(vid, pid, mode, &hid_info)) {
          goto bad_mode;
      }
  
  #else
      // hardware not configured for USB
      goto bad_mode;
  #endif
  
      return mp_const_none;
  
  bad_mode:
      nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "bad USB mode"));
  }
  MP_DEFINE_CONST_FUN_OBJ_KW(pyb_usb_mode_obj, 0, pyb_usb_mode);
  
  /******************************************************************************/
  // Micro Python bindings for USB VCP
  
  /// \moduleref pyb
  /// \class USB_VCP - USB virtual comm port
  ///
  /// The USB_VCP class allows creation of an object representing the USB
  /// virtual comm port.  It can be used to read and write data over USB to
  /// the connected host.
  
  typedef struct _pyb_usb_vcp_obj_t {
      mp_obj_base_t base;
  } pyb_usb_vcp_obj_t;
  
  STATIC const pyb_usb_vcp_obj_t pyb_usb_vcp_obj = {{&pyb_usb_vcp_type}};
  
  STATIC void pyb_usb_vcp_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
      mp_print_str(print, "USB_VCP()");
  }
  
  /// \classmethod \constructor()
  /// Create a new USB_VCP object.
  STATIC mp_obj_t pyb_usb_vcp_make_new(const mp_obj_type_t *type, mp_uint_t n_args, mp_uint_t n_kw, const mp_obj_t *args) {
      // check arguments
      mp_arg_check_num(n_args, n_kw, 0, 0, false);
  
      // TODO raise exception if USB is not configured for VCP
  
      // return the USB VCP object
      return (mp_obj_t)&pyb_usb_vcp_obj;
  }
  
  STATIC mp_obj_t pyb_usb_vcp_setinterrupt(mp_obj_t self_in, mp_obj_t int_chr_in) {
      usb_vcp_set_interrupt_char(mp_obj_get_int(int_chr_in));
      return mp_const_none;
  }
  STATIC MP_DEFINE_CONST_FUN_OBJ_2(pyb_usb_vcp_setinterrupt_obj, pyb_usb_vcp_setinterrupt);
  
  STATIC mp_obj_t pyb_usb_vcp_isconnected(mp_obj_t self_in) {
      return mp_obj_new_bool(USBD_CDC_IsConnected());
  }
  STATIC MP_DEFINE_CONST_FUN_OBJ_1(pyb_usb_vcp_isconnected_obj, pyb_usb_vcp_isconnected);
  
  // deprecated in favour of USB_VCP.isconnected
  STATIC mp_obj_t pyb_have_cdc(void) {
      return pyb_usb_vcp_isconnected(MP_OBJ_NULL);
  }
  MP_DEFINE_CONST_FUN_OBJ_0(pyb_have_cdc_obj, pyb_have_cdc);
  
  /// \method any()
  /// Return `True` if any characters waiting, else `False`.
  STATIC mp_obj_t pyb_usb_vcp_any(mp_obj_t self_in) {
      if (USBD_CDC_RxNum() > 0) {
          return mp_const_true;
      } else {
          return mp_const_false;
      }
  }
  STATIC MP_DEFINE_CONST_FUN_OBJ_1(pyb_usb_vcp_any_obj, pyb_usb_vcp_any);
  
  /// \method send(data, *, timeout=5000)
  /// Send data over the USB VCP:
  ///
  ///   - `data` is the data to send (an integer to send, or a buffer object).
  ///   - `timeout` is the timeout in milliseconds to wait for the send.
  ///
  /// Return value: number of bytes sent.
  STATIC const mp_arg_t pyb_usb_vcp_send_args[] = {
      { MP_QSTR_data,    MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
      { MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 5000} },
  };
  #define PYB_USB_VCP_SEND_NUM_ARGS MP_ARRAY_SIZE(pyb_usb_vcp_send_args)
  
  STATIC mp_obj_t pyb_usb_vcp_send(mp_uint_t n_args, const mp_obj_t *args, mp_map_t *kw_args) {
      // parse args
      mp_arg_val_t vals[PYB_USB_VCP_SEND_NUM_ARGS];
      mp_arg_parse_all(n_args - 1, args + 1, kw_args, PYB_USB_VCP_SEND_NUM_ARGS, pyb_usb_vcp_send_args, vals);
  
      // get the buffer to send from
      mp_buffer_info_t bufinfo;
      uint8_t data[1];
      pyb_buf_get_for_send(vals[0].u_obj, &bufinfo, data);
  
      // send the data
      int ret = USBD_CDC_Tx(bufinfo.buf, bufinfo.len, vals[1].u_int);
  
      return mp_obj_new_int(ret);
  }
  STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_usb_vcp_send_obj, 1, pyb_usb_vcp_send);
  
  /// \method recv(data, *, timeout=5000)
  ///
  /// Receive data on the bus:
  ///
  ///   - `data` can be an integer, which is the number of bytes to receive,
  ///     or a mutable buffer, which will be filled with received bytes.
  ///   - `timeout` is the timeout in milliseconds to wait for the receive.
  ///
  /// Return value: if `data` is an integer then a new buffer of the bytes received,
  /// otherwise the number of bytes read into `data` is returned.
  STATIC mp_obj_t pyb_usb_vcp_recv(mp_uint_t n_args, const mp_obj_t *args, mp_map_t *kw_args) {
      // parse args
      mp_arg_val_t vals[PYB_USB_VCP_SEND_NUM_ARGS];
      mp_arg_parse_all(n_args - 1, args + 1, kw_args, PYB_USB_VCP_SEND_NUM_ARGS, pyb_usb_vcp_send_args, vals);
  
      // get the buffer to receive into
      vstr_t vstr;
      mp_obj_t o_ret = pyb_buf_get_for_recv(vals[0].u_obj, &vstr);
  
      // receive the data
      int ret = USBD_CDC_Rx((uint8_t*)vstr.buf, vstr.len, vals[1].u_int);
  
      // return the received data
      if (o_ret != MP_OBJ_NULL) {
          return mp_obj_new_int(ret); // number of bytes read into given buffer
      } else {
          vstr.len = ret; // set actual number of bytes read
          return mp_obj_new_str_from_vstr(&mp_type_bytes, &vstr); // create a new buffer
      }
  }
  STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_usb_vcp_recv_obj, 1, pyb_usb_vcp_recv);
  
  mp_obj_t pyb_usb_vcp___exit__(mp_uint_t n_args, const mp_obj_t *args) {
      return mp_const_none;
  }
  STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(pyb_usb_vcp___exit___obj, 4, 4, pyb_usb_vcp___exit__);
  
  STATIC const mp_map_elem_t pyb_usb_vcp_locals_dict_table[] = {
      { MP_OBJ_NEW_QSTR(MP_QSTR_setinterrupt), (mp_obj_t)&pyb_usb_vcp_setinterrupt_obj },
      { MP_OBJ_NEW_QSTR(MP_QSTR_isconnected), (mp_obj_t)&pyb_usb_vcp_isconnected_obj },
      { MP_OBJ_NEW_QSTR(MP_QSTR_any), (mp_obj_t)&pyb_usb_vcp_any_obj },
      { MP_OBJ_NEW_QSTR(MP_QSTR_send), (mp_obj_t)&pyb_usb_vcp_send_obj },
      { MP_OBJ_NEW_QSTR(MP_QSTR_recv), (mp_obj_t)&pyb_usb_vcp_recv_obj },
      { MP_OBJ_NEW_QSTR(MP_QSTR_read), (mp_obj_t)&mp_stream_read_obj },
      { MP_OBJ_NEW_QSTR(MP_QSTR_readall), (mp_obj_t)&mp_stream_readall_obj },
      { MP_OBJ_NEW_QSTR(MP_QSTR_readinto), (mp_obj_t)&mp_stream_readinto_obj },
      { MP_OBJ_NEW_QSTR(MP_QSTR_readline), (mp_obj_t)&mp_stream_unbuffered_readline_obj},
      { MP_OBJ_NEW_QSTR(MP_QSTR_readlines), (mp_obj_t)&mp_stream_unbuffered_readlines_obj},
      { MP_OBJ_NEW_QSTR(MP_QSTR_write), (mp_obj_t)&mp_stream_write_obj },
      { MP_OBJ_NEW_QSTR(MP_QSTR_close), (mp_obj_t)&mp_identity_obj },
      { MP_OBJ_NEW_QSTR(MP_QSTR___del__), (mp_obj_t)&mp_identity_obj },
      { MP_OBJ_NEW_QSTR(MP_QSTR___enter__), (mp_obj_t)&mp_identity_obj },
      { MP_OBJ_NEW_QSTR(MP_QSTR___exit__), (mp_obj_t)&pyb_usb_vcp___exit___obj },
  };
  
  STATIC MP_DEFINE_CONST_DICT(pyb_usb_vcp_locals_dict, pyb_usb_vcp_locals_dict_table);
  
  STATIC mp_uint_t pyb_usb_vcp_read(mp_obj_t self_in, void *buf, mp_uint_t size, int *errcode) {
      int ret = USBD_CDC_Rx((byte*)buf, size, 0);
      if (ret == 0) {
          // return EAGAIN error to indicate non-blocking
          *errcode = MP_EAGAIN;
          return MP_STREAM_ERROR;
      }
      return ret;
  }
  
  STATIC mp_uint_t pyb_usb_vcp_write(mp_obj_t self_in, const void *buf, mp_uint_t size, int *errcode) {
      int ret = USBD_CDC_Tx((const byte*)buf, size, 0);
      if (ret == 0) {
          // return EAGAIN error to indicate non-blocking
          *errcode = MP_EAGAIN;
          return MP_STREAM_ERROR;
      }
      return ret;
  }
  
  STATIC mp_uint_t pyb_usb_vcp_ioctl(mp_obj_t self_in, mp_uint_t request, mp_uint_t arg, int *errcode) {
      mp_uint_t ret;
      if (request == MP_IOCTL_POLL) {
          mp_uint_t flags = arg;
          ret = 0;
          if ((flags & MP_IOCTL_POLL_RD) && USBD_CDC_RxNum() > 0) {
              ret |= MP_IOCTL_POLL_RD;
          }
          if ((flags & MP_IOCTL_POLL_WR) && USBD_CDC_TxHalfEmpty()) {
              ret |= MP_IOCTL_POLL_WR;
          }
      } else {
          *errcode = MP_EINVAL;
          ret = MP_STREAM_ERROR;
      }
      return ret;
  }
  
  STATIC const mp_stream_p_t pyb_usb_vcp_stream_p = {
      .read = pyb_usb_vcp_read,
      .write = pyb_usb_vcp_write,
      .ioctl = pyb_usb_vcp_ioctl,
  };
  
  const mp_obj_type_t pyb_usb_vcp_type = {
      { &mp_type_type },
      .name = MP_QSTR_USB_VCP,
      .print = pyb_usb_vcp_print,
      .make_new = pyb_usb_vcp_make_new,
      .getiter = mp_identity,
      .iternext = mp_stream_unbuffered_iter,
      .stream_p = &pyb_usb_vcp_stream_p,
      .locals_dict = (mp_obj_t)&pyb_usb_vcp_locals_dict,
  };
  
  /******************************************************************************/
  // Micro Python bindings for USB HID
  
  typedef struct _pyb_usb_hid_obj_t {
      mp_obj_base_t base;
  } pyb_usb_hid_obj_t;
  
  STATIC const pyb_usb_hid_obj_t pyb_usb_hid_obj = {{&pyb_usb_hid_type}};
  
  STATIC mp_obj_t pyb_usb_hid_make_new(const mp_obj_type_t *type, mp_uint_t n_args, mp_uint_t n_kw, const mp_obj_t *args) {
      // check arguments
      mp_arg_check_num(n_args, n_kw, 0, 0, false);
  
      // TODO raise exception if USB is not configured for HID
  
      // return the USB HID object
      return (mp_obj_t)&pyb_usb_hid_obj;
  }
  
  STATIC mp_obj_t pyb_usb_hid_send(mp_obj_t self_in, mp_obj_t report_in) {
  #ifdef USE_DEVICE_MODE
      mp_buffer_info_t bufinfo;
      byte temp_buf[8];
      // get the buffer to send from
      // we accept either a byte array, or a tuple/list of integers
      if (!mp_get_buffer(report_in, &bufinfo, MP_BUFFER_READ)) {
          mp_obj_t *items;
          mp_obj_get_array(report_in, &bufinfo.len, &items);
          if (bufinfo.len > sizeof(temp_buf)) {
              nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "tuple/list too large for HID report; use bytearray instead"));
          }
          for (int i = 0; i < bufinfo.len; i++) {
              temp_buf[i] = mp_obj_get_int(items[i]);
          }
          bufinfo.buf = temp_buf;
      }
  
      // send the data
      USBD_HID_SendReport(&hUSBDDevice, bufinfo.buf, bufinfo.len);
  #endif
  
      return mp_const_none;
  }
  STATIC MP_DEFINE_CONST_FUN_OBJ_2(pyb_usb_hid_send_obj, pyb_usb_hid_send);
  
  // deprecated in favour of USB_HID.send
  STATIC mp_obj_t pyb_hid_send_report(mp_obj_t arg) {
      return pyb_usb_hid_send(MP_OBJ_NULL, arg);
  }
  MP_DEFINE_CONST_FUN_OBJ_1(pyb_hid_send_report_obj, pyb_hid_send_report);
  
  STATIC const mp_map_elem_t pyb_usb_hid_locals_dict_table[] = {
      { MP_OBJ_NEW_QSTR(MP_QSTR_send), (mp_obj_t)&pyb_usb_hid_send_obj },
  };
  
  STATIC MP_DEFINE_CONST_DICT(pyb_usb_hid_locals_dict, pyb_usb_hid_locals_dict_table);
  
  STATIC mp_uint_t pyb_usb_hid_ioctl(mp_obj_t self_in, mp_uint_t request, mp_uint_t arg, int *errcode) {
      mp_uint_t ret;
      if (request == MP_IOCTL_POLL) {
          mp_uint_t flags = arg;
          ret = 0;
          if ((flags & MP_IOCTL_POLL_WR) && USBD_HID_CanSendReport(&hUSBDDevice)) {
              ret |= MP_IOCTL_POLL_WR;
          }
      } else {
          *errcode = MP_EINVAL;
          ret = MP_STREAM_ERROR;
      }
      return ret;
  }
  
  STATIC const mp_stream_p_t pyb_usb_hid_stream_p = {
      .ioctl = pyb_usb_hid_ioctl,
  };
  
  const mp_obj_type_t pyb_usb_hid_type = {
      { &mp_type_type },
      .name = MP_QSTR_USB_HID,
      .make_new = pyb_usb_hid_make_new,
      .stream_p = &pyb_usb_hid_stream_p,
      .locals_dict = (mp_obj_t)&pyb_usb_hid_locals_dict,
  };
  
  /******************************************************************************/
  // code for experimental USB OTG support
  
  #ifdef USE_HOST_MODE
  
  #include "led.h"
  #include "usbh_core.h"
  #include "usbh_usr.h"
  #include "usbh_hid_core.h"
  #include "usbh_hid_keybd.h"
  #include "usbh_hid_mouse.h"
  
  __ALIGN_BEGIN USBH_HOST USB_Host __ALIGN_END ;
  
  static int host_is_enabled = 0;
  
  void pyb_usb_host_init(void) {
      if (!host_is_enabled) {
          // only init USBH once in the device's power-lifetime
          /* Init Host Library */
          USBH_Init(&USB_OTG_Core, USB_OTG_FS_CORE_ID, &USB_Host, &HID_cb, &USR_Callbacks);
      }
      host_is_enabled = 1;
  }
  
  void pyb_usb_host_process(void) {
      USBH_Process(&USB_OTG_Core, &USB_Host);
  }
  
  uint8_t usb_keyboard_key = 0;
  
  // TODO this is an ugly hack to get key presses
  uint pyb_usb_host_get_keyboard(void) {
      uint key = usb_keyboard_key;
      usb_keyboard_key = 0;
      return key;
  }
  
  void USR_MOUSE_Init(void) {
      led_state(4, 1);
      USB_OTG_BSP_mDelay(100);
      led_state(4, 0);
  }
  
  void USR_MOUSE_ProcessData(HID_MOUSE_Data_TypeDef *data) {
      led_state(4, 1);
      USB_OTG_BSP_mDelay(50);
      led_state(4, 0);
  }
  
  void USR_KEYBRD_Init(void) {
      led_state(4, 1);
      USB_OTG_BSP_mDelay(100);
      led_state(4, 0);
  }
  
  void USR_KEYBRD_ProcessData(uint8_t pbuf) {
      led_state(4, 1);
      USB_OTG_BSP_mDelay(50);
      led_state(4, 0);
      usb_keyboard_key = pbuf;
  }
  
  #endif // USE_HOST_MODE
  