Still celebrating National IT Professionals Day with 3 months of free Premium Membership. Use Code ITDAY17

x
?
Solved

Logarithm for CRC16

Posted on 1999-07-07
5
Medium Priority
?
297 Views
Last Modified: 2012-05-04
Hi!

Could anyone give me the logarithm for CRC16 (16 bit CRC)
an example on a short message (about 5 bytes) would be very nice!

Thanks!
0
Comment
Question by:uffe78
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
5 Comments
 
LVL 84

Expert Comment

by:ozo
ID: 1263366
The logarithm?
0
 
LVL 1

Expert Comment

by:BSoeters
ID: 1263367
Probably the algorithm :)
0
 
LVL 1

Expert Comment

by:BSoeters
ID: 1263368
Nice anagram though :)
0
 
LVL 14

Accepted Solution

by:
AlexVirochovsky earned 150 total points
ID: 1263369
This is programm for make CRC16 (for messages)
unsigned short CRC(unsigned char *lpuchMsg, unsigned short ushDataLen)
{
  unsigned char uchCRCHI = 0xFF;
  unsigned char uchCRCLO = 0xFF;
  unsigned uIndex;
  static unsigned char auchCRCHi[] =
   { //1   2     3     4     5    6    7    8    9    10   11  12   13    14   15
     0x00,0xC1, 0x81, 0x40, 0x01,0xc0,0x80,0x41,0x01,0xc0,0x80,0x41,0x00,0xc1,0x81,
     0x40,0x01, 0xc0, 0x80, 0x41,0x00,0xc1,0x81,0x40,0x00,0xc1,0x81,0x40,0x01,0xc0,
     0x80,0x41, 0x01, 0xc0, 0x80,0x41,0x00,0xc1,0x81,0x40,0x00,0xc1,0x81,0x40,0x01,
     0xc0,0x80, 0x41, 0x00, 0xc1,0x81,0x40,0x01,0xc0,0x80,0x41,0x01,0xc0,0x80,0x41,
     0x00,0xC1, 0x81, 0x40, 0x01,0xc0,0x80,0x41,0x00,0xc1,0x81,0x40,0x00,0xc1,0x81,
     0x40,0x01, 0xc0, 0x80, 0x41,0x00,0xc1,0x81,0x40,0x01,0xc0,0x80,0x41,0x01,0xc0,
     0x80,0x41, 0x00, 0xc1, 0x81,0x40,0x00,0xc1,0x81,0x40,0x01,0xc0,0x80,0x41,0x01,
     0xc0,0x80, 0x41, 0x00, 0xc1,0x81,0x40,0x01,0xc0,0x80,0x41,0x00,0xc1,0x81,0x40,
     0x00,0xC1, 0x81, 0x40, 0x01,0xc0,0x80,0x41,0x01,0xc0,0x80,0x41,0x00,0xc1,0x81,
     0x40,0x00, 0xc1, 0x81, 0x40,0x01,0xc0,0x80,0x41,0x00,0xc1,0x81,0x40,0x01,0xc0,
     0x80,0x41, 0x01, 0xc0, 0x80,0x41,0x00,0xc1,0x81,0x40,0x00,0xc1,0x81,0x40,0x01,
     0xC0,0x80, 0x41, 0x01, 0xc0,0x80,0x41,0x00,0xc1,0x81,0x40,0x01,0xc0,0x80,0x41,
     0x00,0xC1, 0x81, 0x40, 0x00,0xc1,0x81,0x40,0x01,0xc0,0x80,0x41,0x00,0xc1,0x81,
     0x40,0x01, 0xc0, 0x80, 0x41,0x01,0xc0,0x80,0x41,0x00,0xc1,0x81,0x40,0x01,0xc0,
     0x80,0x41, 0x00, 0xc1, 0x81,0x40,0x00,0xc1,0x81,0x40,0x01,0xc0,0x80,0x41,0x01,
     0xc0,0x80, 0x41, 0x00, 0xc1,0x81,0x40,0x00,0xc1,0x81,0x40,0x01,0xc0,0x80,0x41,
     0x00,0xC1, 0x81, 0x40, 0x01,0xc0,0x80,0x41,0x01,0xc0,0x80,0x41,0x00,0xc1,0x81,
     0x40
   };

  static unsigned char auchCRCLo[] =
   { //1   2     3     4     5    6    7    8    9    10   11  12   13    14   15
     0x00,0xC0, 0xc1, 0x01, 0xc3,0x03,0x02,0xc2,0xc6,0x06,0x07,0xc7,0x05,0xc5,0xc4,
     0x04,0xcc, 0x0c, 0x0d, 0xcd,0x0f,0xcf,0xce,0x0e,0x0a,0xca,0xcb,0x0b,0xc9,0x09,
     0x08,0xc8, 0xd8, 0x18, 0x19,0xd9,0x1b,0xdb,0xda,0x1a,0x1e,0xde,0xdf,0x1f,0xdd,
     0x1d,0x1c, 0xdc, 0x14, 0xd4,0xd5,0x15,0xd7,0x17,0x16,0xd6,0xd2,0x12,0x13,0xd3,
     0x11,0xd1, 0xd0, 0x10, 0xf0,0x30,0x31,0xf1,0x33,0xf3,0xf2,0x32,0x36,0xf6,0xf7,
     0x37,0xf5, 0x35, 0x34, 0xf4,0x3c,0xfc,0xfd,0x3d,0xff,0x3f,0x3e,0xfe,0xfa,0x3a,
     0x3b,0x41, 0x39, 0xf9, 0xf8,0x38,0x28,0xe8,0xe9,0x29,0xeb,0x2b,0x2a,0xea,0xee,
     0x2e,0xfb, 0xef, 0x2d, 0xed,0xec,0x2c,0xe4,0x24,0x25,0xe5,0x27,0xe7,0xe6,0x26,
     0x22,0x2f, 0xe3, 0x23, 0xe1,0x21,0x20,0xe0,0xa0,0x60,0x61,0xa1,0x63,0xa3,0xa2,
     0x62,0xe2, 0xa6, 0xa7, 0x67,0xa5,0x65,0x64,0xa4,0x6c,0xac,0xad,0x6d,0xaf,0x6f,
     0x6e,0xae, 0xaa, 0x6a, 0x6b,0xab,0x69,0xa9,0xa8,0x68,0x78,0xb8,0xb9,0x79,0xbb,
     0x7b,0x7a, 0xba, 0xbe, 0x7e,0x7f,0xbf,0x7d,0xbd,0xbc,0x7c,0xb4,0x74,0x75,0xb5,
     0x77,0xb7, 0xb6, 0x76, 0x72,0xb2,0xb3,0x73,0xb1,0x71,0x70,0xb0,0x50,0x90,0x91,
     0x51,0x93, 0x53, 0x52, 0x92,0x96,0x56,0x57,0x97,0x55,0x95,0x94,0x54,0x9c,0x5c,
     0x5d,0x9d, 0x5f, 0x9f, 0x9e,0x5e,0x5a,0x9a,0x9b,0x5b,0x99,0x59,0x5b,0x98,0x88,
     0x4b,0x49, 0x89, 0x4b, 0x8b,0x8a,0x4a,0x4e,0x8e,0x8f,0x4f,0x8d,0x40,0x41,0x8c,
     0x44,0x84, 0x85, 0x45, 0x87,0x47,0x46,0x86,0x82,0x42,0x43,0x83,0x41,0x81,0x80,
     0x40
   };
  while(ushDataLen--)
    {
      uIndex = uchCRCHI ^ *lpuchMsg++;
      uchCRCHI = uchCRCLO ^ auchCRCHi[uIndex];
      uchCRCLO = auchCRCLo[uIndex];
    }
  return (uchCRCHI<< 8) | uchCRCLO;
}
Good Luck, Alex
0
 

Author Comment

by:uffe78
ID: 1263370
Thanks BSoethers, one point for you...
0

Featured Post

Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Summary: This tutorial covers some basics of pointer, pointer arithmetic and function pointer. What is a pointer: A pointer is a variable which holds an address. This address might be address of another variable/address of devices/address of fu…
Examines three attack vectors, specifically, the different types of malware used in malicious attacks, web application attacks, and finally, network based attacks.  Concludes by examining the means of securing and protecting critical systems and inf…
Video by: Grant
The goal of this video is to provide viewers with basic examples to understand and use nested-loops in the C programming language.
The goal of this video is to provide viewers with basic examples to understand and use conditional statements in the C programming language.

722 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question