include/hidpacket.h

   1 //      Copyright (C) 2014 Michael McMaster <michael@codesrc.com>
   2 //
   3 //      This file is part of SCSI2SD.
   4 //
   5 //      SCSI2SD is free software: you can redistribute it and/or modify
   6 //      it under the terms of the GNU General Public License as published by
   7 //      the Free Software Foundation, either version 3 of the License, or
   8 //      (at your option) any later version.
   9 //
  10 //      SCSI2SD is distributed in the hope that it will be useful,
  11 //      but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 //      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 //      GNU General Public License for more details.
  14 //
  15 //      You should have received a copy of the GNU General Public License
  16 //      along with SCSI2SD.  If not, see <http://www.gnu.org/licenses/>.
  17
  18 // Library for sending packet data over a USB HID connection.
  19 // Supports reassembly of packets larger than the HID packet,
  20
  21 #ifdef __cplusplus
  22 extern "C" {
  23 #endif
  24
  25 #define USBHID_LEN 64
  26
  27 // Maximum packet payload length. Must be large enough to support a SD sector
  28 // + sector number
  29 #define HIDPACKET_MAX_LEN 520
  30
  31 #include <stddef.h>
  32 #include <stdint.h>
  33
  34 // The first byte of each HID packet contains the hid chunk number.
  35 //   High-bit indicates a final chunk.
  36 // The second byte of each HID packet contains the payload length.
  37
  38 // Call this with HID bytes received. len <= USBHID_LEN
  39 void hidPacket_recv(const uint8_t* bytes, size_t len);
  40
  41 // Returns the received packet contents, or NULL if a complete packet isn't
  42 // available.
  43 const uint8_t* hidPacket_getPacket(size_t* len);
  44
  45 // Returns the received packet contents, or NULL if a complete packet isn't
  46 // available.
  47 const uint8_t* hidPacket_peekPacket(size_t* len);
  48
  49 // Call this with packet data to send. len <= USBHID_LEN
  50 // Overwrites any packet currently being sent.
  51 void hidPacket_send(const uint8_t* bytes, size_t len);
  52
  53 // Returns USBHID_LEN bytes to send in the next HID packet, or
  54 // NULL if there's nothing to send.
  55 const uint8_t* hidPacket_getHIDBytes(uint8_t* hidBuffer);
  56
  57 #ifdef __cplusplus
  58 } // extern "C"
  59 #endif
  60