text: /*
   * This file is part of the TREZOR project, https://trezor.io/
   *
   * Copyright (c) SatoshiLabs
   *
   * This program is free software: you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation, either version 3 of the License, or
   * (at your option) any later version.
   *
   * This program 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 General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
   */
  
  #include <stddef.h>
  
  typedef struct __attribute__((packed)) {
    uint8_t bFunctionLength;
    uint8_t bDescriptorType;
    uint8_t bDescriptorSubtype;
    uint16_t bcdCDC;
  } usb_vcp_header_descriptor_t;
  
  typedef struct __attribute__((packed)) {
    uint8_t bFunctionLength;
    uint8_t bDescriptorType;
    uint8_t bDescriptorSubtype;
    uint8_t bmCapabilities;
    uint8_t bDataInterface;
  } usb_vcp_cm_descriptor_t;
  
  typedef struct __attribute__((packed)) {
    uint8_t bFunctionLength;
    uint8_t bDescriptorType;
    uint8_t bDescriptorSubtype;
    uint8_t bmCapabilities;
  } usb_vcp_acm_descriptor_t;
  
  typedef struct __attribute__((packed)) {
    uint8_t bFunctionLength;
    uint8_t bDescriptorType;
    uint8_t bDescriptorSubtype;
    uint8_t bControlInterface;
    uint8_t bSubordinateInterface0;
  } usb_vcp_union_descriptor_t;
  
  typedef struct __attribute__((packed)) {
    usb_interface_assoc_descriptor_t assoc;
    usb_interface_descriptor_t iface_cdc;
    usb_vcp_header_descriptor_t
        fheader;                  // Class-Specific Descriptor Header Format
    usb_vcp_cm_descriptor_t fcm;  // Call Management Functional Descriptor
    usb_vcp_acm_descriptor_t
        facm;  // Abstract Control Management Functional Descriptor
    usb_vcp_union_descriptor_t funion;  // Union Interface Functional Descriptor
    usb_endpoint_descriptor_t ep_cmd;
    usb_interface_descriptor_t iface_data;
    usb_endpoint_descriptor_t ep_in;
    usb_endpoint_descriptor_t ep_out;
  } usb_vcp_descriptor_block_t;
  
  typedef struct __attribute__((packed)) {
    uint32_t dwDTERate;
    uint8_t bCharFormat;  // usb_cdc_line_coding_bCharFormat_t
    uint8_t bParityType;  // usb_cdc_line_coding_bParityType_t
    uint8_t bDataBits;
  } usb_cdc_line_coding_t;
  
  typedef enum {
    USB_CDC_1_STOP_BITS = 0,
    USB_CDC_1_5_STOP_BITS = 1,
    USB_CDC_2_STOP_BITS = 2,
  } usb_cdc_line_coding_bCharFormat_t;
  
  typedef enum {
    USB_CDC_NO_PARITY = 0,
    USB_CDC_ODD_PARITY = 1,
    USB_CDC_EVEN_PARITY = 2,
    USB_CDC_MARK_PARITY = 3,
    USB_CDC_SPACE_PARITY = 4,
  } usb_cdc_line_coding_bParityType_t;
  
  /* usb_vcp_info_t contains all information for setting up a VCP interface.  All
   * passed pointers need to live at least until the interface is disabled
   * (usb_stop is called). */
  typedef struct {
    uint8_t *tx_packet;  // Buffer for one packet, with length of at least
                         // max_packet_len bytes
    uint8_t *tx_buffer;  // Buffer for IN EP ring buffer, with length of at least
                         // tx_buffer_len bytes
    uint8_t *rx_packet;  // Buffer for one packet, with length of at least
                         // max_packet_len bytes
    uint8_t *rx_buffer;  // Buffer for OUT EP ring buffer, with length of at least
                         // rx_buffer_len bytes
    size_t tx_buffer_len;      // Length of tx_buffer, needs to be a power of 2
    size_t rx_buffer_len;      // Length of rx_buffer, needs to be a power of 2
    void (*rx_intr_fn)(void);  // Callback called from usb_vcp_class_data_out IRQ
                               // handler if rx_intr_byte matches
    uint8_t rx_intr_byte;      // Value matched against every received byte
    uint8_t iface_num;         // Address of this VCP interface
    uint8_t data_iface_num;    // Address of data interface of the VCP interface
                               // association
    uint8_t ep_cmd;  // Address of IN CMD endpoint (with the highest bit set)
    uint8_t ep_in;   // Address of IN endpoint (with the highest bit set)
    uint8_t ep_out;  // Address of OUT endpoint
    uint8_t polling_interval;  // In units of 1ms
    uint8_t max_packet_len;  // Length of the biggest packet, and of tx_packet and
                             // rx_packet
  } usb_vcp_info_t;
  
  /* usb_rbuf_t is used internally for the RX/TX buffering. */
  typedef struct {
    size_t cap;
    volatile size_t read;
    volatile size_t write;
    uint8_t *buf;
  } usb_rbuf_t;
  
  // Maximal length of packets on IN CMD EP
  #define USB_CDC_MAX_CMD_PACKET_LEN 0x08
  
  /* usb_vcp_state_t encapsulates all state used by enabled VCP interface.  It
   * needs to be completely initialized in usb_vcp_add and reset in
   * usb_vcp_class_init.  See usb_vcp_info_t for details of the configuration
   * fields. */
  typedef struct {
    const usb_vcp_descriptor_block_t *desc_block;
    usb_rbuf_t rx_ring;
    usb_rbuf_t tx_ring;
    uint8_t *rx_packet;
    uint8_t *tx_packet;
    void (*rx_intr_fn)(void);
    uint8_t rx_intr_byte;
    uint8_t ep_cmd;
    uint8_t ep_in;
    uint8_t ep_out;
    uint8_t max_packet_len;
    uint8_t ep_in_is_idle;  // Set to 1 after IN endpoint gets idle
    uint8_t cmd_buffer[USB_CDC_MAX_CMD_PACKET_LEN];
  } usb_vcp_state_t;
  
  secbool __wur usb_vcp_add(const usb_vcp_info_t *vcp_info);
  secbool __wur usb_vcp_can_read(uint8_t iface_num);
  secbool __wur usb_vcp_can_write(uint8_t iface_num);
  int __wur usb_vcp_read(uint8_t iface_num, uint8_t *buf, uint32_t len);
  int __wur usb_vcp_write(uint8_t iface_num, const uint8_t *buf, uint32_t len);
  
  int __wur usb_vcp_read_blocking(uint8_t iface_num, uint8_t *buf, uint32_t len,
                                  int timeout);
  int __wur usb_vcp_write_blocking(uint8_t iface_num, const uint8_t *buf,
                                   uint32_t len, int timeout);
  