Btoa definition

Btoa





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2 definitions found

From Virtual Entity of Relevant Acronyms (Version 1.9, June 2002) [vera]:

  BTOA
       Binary TO ASCII (ASCII)
       
       

From The Free On-line Dictionary of Computing (27 SEP 03) [foldoc]:



  btoa
       
           /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)
       
       

















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