btoa

2 definitions found

btoa - Free On-line Dictionary of Computing (26 May 2007) :

  btoa
  
     <tool, messaging, algorithm, file format> /B too A/ A binary
     to ASCII conversion utility.
  
     btoa is a uuencode or base 64 equivalent which addresses
     some of the problems with the uuencode standard but not as
     many as the base 64 standard.  It avoids problems that some
     hosts have with spaces (e.g. conversion of groups of spaces
     to tabs) by not including them in its character set, but may
     still have problems on non-ASCII systems (e.g. EBCDIC).
  
     btoa is primarily used to transfer binary files between
     systems across connections which are not eight-bit clean,
     e.g. electronic mail.
  
     btoa takes adjacent sets of four binary octets and encodes
     them as five ASCII octets using ASCII characters '!' through
     to 'u'.  Special characters are also used: 'x' marks the
     beginning or end of the archive; 'z' marks four consecutive
     zeros and 'y' (version 5.2) four consecutive spaces.
  
     Each group of four octets is processed as a 32-bit integer.
     Call this 'I'.  Let 'D' = 85^4.  Divide I by D.  Call this
     result 'R'.  Make I = I - (R * D) to avoid overflow on the
     next step.  Repeat, for values of D = 85^3, 85^2, 85 and 1.
     At each step, to convert R to the output character add decimal
     33 (output octet = R + ASCII value for '!').  Five output
     octets are produced.
  
     btoa provides some integrity checking in the form of a line
     checksum, and facilities for patching corrupted downloads.
  
     The algorithm used by btoa is more efficient than uuencode
     or base 64.  ASCII files are encoded to about 120% the size of
     their binary sources.  This compares with 135% for uuencode or
     base 64.
  
     C source (ftp://hpux.csc.liv.ac.uk/hpux/Misc/btoa-5.2/).
     (version 5.2 - ~1994).
  
     Pre-compiled MS-DOS versions are also available.
  
     (1997-08-08)
  

btoa - V.E.R.A. -- Virtual Entity of Relevant Acronyms (June 2006) :

  BTOA
         Binary TO ASCII (ASCII)