/*********************************************************************************
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* Copyright: (C) 2019 LingYun IoT studio
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* All rights reserved.
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*
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* Filename: tlv_sample.c
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* Description: This file
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*
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* Version: 1.0.0(03/27/2019)
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* Author: Guo Wenxue <guowenxue@gmail.com>
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* ChangeLog: 1, Release initial version on "03/27/2019 09:20:25 PM"
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*
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********************************************************************************/
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#include <stdio.h>
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#include <string.h>
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#include "crc-itu-t.h"
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#define OFF 0
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#define ON 1
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#define BUFSIZE 128
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/* TLV Packet format:
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*
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*+------------+---------+------------+-----------+-----------+
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*| Header(1B) | Tag(1B) | Length(1B) | Value(1B) | CRC16(2B) |
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*+------------+---------+------------+-----------+-----------+
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*/
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#define PACK_HEADER 0xFD
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/* Tag definition */
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enum
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{
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TAG_LOGON=1,
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TAG_CAMERA,
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TAG_LED,
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};
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/* TLV packet fixed segement size, 1B Head, 1B Tag, 1B length, 2B CRC16, total 5B. */
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#define TLV_FIXED_SIZE 5
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/* TLV packet Minimum size is fixed bytes + 1 byte data */
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#define TLV_MIN_SIZE (TLV_FIXED_SIZE+1)
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int packtlv_logon(char *buf, int size, char *pwd);
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int packtlv_led(char *buf, int size, int cmd);
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void dump_buf(char *data, int len);
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int main(int argc, char **argv)
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{
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char buf[BUFSIZE];
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int bytes;
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bytes = packtlv_led(buf, sizeof(buf), ON);
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/* print every byte in the buffer as HEX and corresponding charactor,
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which is not printable charactor will be instead as '?' */
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dump_buf(buf, bytes);
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bytes = packtlv_logon(buf, sizeof(buf), "iot@yun");
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dump_buf(buf, bytes);
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return 0;
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}
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int packtlv_logon(char *buf, int size, char *pwd)
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{
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unsigned short crc16 = 0;
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int pack_len = 0;
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int data_len = 0;
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int ofset = 0; /* index position for the buf */
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if(!buf || !pwd || size<TLV_MIN_SIZE )
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{
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printf("Invalid input arguments\n");
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return 0;
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}
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/* Packet head */
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buf[ofset] = PACK_HEADER;
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ofset += 1;
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/* Tag */
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buf[ofset] = TAG_LOGON;
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ofset += 1;
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/* $pwd too long maybe result buffer overflow, so we need check the buffer
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* is large enuf or not. If buf size is not enuf we will truncate $pwd string */
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if( strlen(pwd) <= size-TLV_FIXED_SIZE )
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data_len = strlen(pwd);
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else
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data_len = size-TLV_FIXED_SIZE;
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/* Length, this packet is passwd length+5Byte () */
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pack_len = data_len + TLV_FIXED_SIZE;
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buf[ofset] = pack_len;
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ofset += 1;
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memcpy(&buf[ofset], pwd, data_len);
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ofset += data_len;
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/* Calc CRC16 checksum value from Packet Head(buf[0])~ Value(buf[ofset]) */
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crc16 = crc_itu_t(MAGIC_CRC, buf, ofset);
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/* Append the 2 Bytes CRC16 checksum value into the last two bytes in packet buffer */
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ushort_to_bytes(&buf[ofset], crc16);
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ofset += 2;
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return ofset;
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}
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int packtlv_led(char *buf, int size, int cmd)
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{
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unsigned short crc16;
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int pack_len = TLV_FIXED_SIZE+1; /* Only 1 byte data */
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if(!buf || size<TLV_MIN_SIZE )
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{
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printf("Invalid input arguments\n");
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return 0;
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}
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/* Packet head */
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buf[0] = PACK_HEADER;
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/* Tag */
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buf[1] = TAG_LED;
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/* Length, this packet total 6 bytes */
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buf[2] = pack_len;
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/* Value */
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buf[3] = (OFF==cmd) ? 0x00 : 0x01;
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/* Calc CRC16 checksum value from Packet Head(buf[0])~ Packet Value(buf[3]) */
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crc16 = crc_itu_t(MAGIC_CRC, buf, 4);
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/* Append the 2 Bytes CRC16 checksum value into the last two bytes in packet buffer */
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ushort_to_bytes(&buf[4], crc16);
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return pack_len;
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}
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/*+------------------------------+
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*| dump_buf() implement code |
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*+------------------------------+*/
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#define LINELEN 81
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#define CHARS_PER_LINE 16
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static char *print_char =
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" "
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" "
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" !\"#$%&'()*+,-./"
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"0123456789:;<=>?"
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"@ABCDEFGHIJKLMNO"
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"PQRSTUVWXYZ[\\]^_"
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"`abcdefghijklmno"
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"pqrstuvwxyz{|}~ "
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" "
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" "
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" ???????????????"
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"????????????????"
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"????????????????"
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"????????????????"
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"????????????????"
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"????????????????";
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/* print every byte in the buffer as HEX and corresponding charactor, which is not printable charactor will be instead as '?' */
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void dump_buf(char *data, int len)
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{
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int rc;
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int idx;
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char prn[LINELEN];
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char lit[CHARS_PER_LINE + 1];
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char hc[4];
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short line_done = 1;
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rc = len;
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idx = 0;
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lit[CHARS_PER_LINE] = '\0';
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while (rc > 0)
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{
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if (line_done)
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snprintf(prn, LINELEN, "%08X: ", idx);
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do
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{
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unsigned char c = data[idx];
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snprintf(hc, 4, "%02X ", c);
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strncat(prn, hc, 4);
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lit[idx % CHARS_PER_LINE] = print_char[c];
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++idx;
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} while (--rc > 0 && (idx % CHARS_PER_LINE != 0));
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line_done = (idx % CHARS_PER_LINE) == 0;
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if (line_done)
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printf("%s %s\n", prn, lit);
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else if (rc == 0)
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strncat(prn, " ", LINELEN);
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}
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if (!line_done)
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{
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lit[(idx % CHARS_PER_LINE)] = '\0';
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while ((++idx % CHARS_PER_LINE) != 0)
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strncat(prn, " ", LINELEN);
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printf("%s %s\n", prn, lit);
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}
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}
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