\ Deflate files of the gzip format
needs comp/c io/core comp/sig
unit ar/ungz

cc<< ar/puff.c

: _err abort"ungz error" ;
: _assert not if _err then ;

: _skiptonull ( rb -- ) begin dup getc# not until drop ;

create hdr 10 allot
\ Take a gzip file from reader and spit the deflated version in writer
: ungz ( reader writer -- err )
  swap hdr 10 oover read#
  hdr wbe@ $1f8b = _assert \ ID1+ID2
  hdr 2+ c@ 8 = _assert \ CM
  hdr 3 + c@ dup $04 and if ( wr rb flg ) \ FLG.EXTRA
    over hdr 2 oover read# ( wr rb flg rb )
    here hdr wle@ ( xlen ) rot read# then \ read extra
  dup $08 and if over _skiptonull then \ FLG.NAME
  $10 and if dup _skiptonull then ( wr rb ) \ FLG.COMMENT
  2dup puff rot> close close ;