Class: CRC8Stream

• Inheritance
• Description
• Related information
• Class protocol
  • instance creation
  • queries
• Instance protocol
  • initialization
  • queries
• Examples

Inheritance:

   Object
   |
   +--Stream
      |
      +--HashStream
         |
         +--CRCStream
            |
            +--CRC8Stream

Package:

stx:libbasic2

Category:

System-Crypt-Hashing

Version:

rev: 1.2 date: 2019/03/25 13:33:39

user: cg

file: CRC8Stream.st directory: libbasic2

module: stx stc-classLibrary: libbasic2

Author:

Claus Gittinger

Description:

ATTENTION: CRC8Stream is currently BROKEN (in development)

newSAE_J1850:
  Standard CRC method as defined by SAE J1850 (used in AUTOSAR)
  The polynomial is 0x1D; initial value 0xFF; xorOut is 0xFF
  

[instance variables:]

[class variables:]

Related information:

    SHA1Stream
    MD5Stream

Class protocol:

 generatorPolynomMSB: anInteger

notice, in literature, the generator polynom is usually specified as an MSB number

 generatorPolynomMSB: anInteger initValue: initValue

notice, in literature, the generator polynom is usually specified as an MSB number

 generatorPolynomMSB: anInteger initValue: initValueArg xorOut: xorOut

notice, in literature, the generator polynom is usually specified as an MSB number

 newSAE_J1850

return an instance of the SAE_J1850 CRC8 (used in AUTOSAR)

 new_2F

return an instance of the CRC8-2F (used in AUTOSAR).
Currently broken.

 hashSize

return the size of the hashvalue returned by instances of this class (in bytes)

Instance protocol:

 generatorPolynom: anLSBInteger

set the generator polynom for this instance,
set start and xorOut to 16rFF.
Note: you have to set the bit-reversed value, so the LSB must be first

 generatorPolynom: anLSBInteger initValue: initValueArg

set the generator polynom for this instance.
set start to initValueArg and xorOut to 16rFF.
Note: you have to set the bit-reversed value, so the LSB must be first

 hashValue

return the computed CRC

Examples:

  self information:(CRC8Stream new hashValueOf:'resume') hexPrintString

  self information:(CRC16Stream new
                          nextPut:$r;
                          nextPut:$e;
                          nextPut:$s;
                          nextPut:$u;
                          nextPut:$m;
                          nextPut:$e;
                          hashValue) hexPrintString

  self information:(CRC16Stream hashValueOf:#[1 2 3 4 5 6 7]) hexPrintString

  self information:((CRC16Stream hashValueOf:#[16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF
           16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF
           16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF
           16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF]) hexPrintString)

  |hashStream n t|

  hashStream := CRC16Stream new.
  n := 1000000.
  t := Time millisecondsToRun:[
          n timesRepeat:[
              hashStream nextPutAll:'12345678901234567890123456789012345678901234567890'.
          ].
       ].
  t := (t / 1000) asFloat.
  Transcript show:'crc16:'; showCR: hashStream hashValue hexPrintString.
  Transcript show:t; show:' seconds for '; show:(50*n/1024) asFloat; showCR:' Kb'.
  Transcript show:(n*50/1024 / t); showCR:' Kb/s'