( MATCHC                              find substring in string )

need j need pick need roll
: matchc                          ( adr1 n1 adr2 n2 --- adr3 f )
  swap dup c@ 5 pick 5 roll +     ( adr1 n2 adr2 b adr1+n1 --- )
  dup 1 swap 6 pick - 1+ 7 roll
  do 3 pick i c@ =                 ( search for b in string)
    if 0 6 pick 1 do               ( found, compare rest)
      j i + c@ 6 pick i + c@       ( fetch next search byte)
      = 0=                         ( do they match?)
      if drop 1 leave endif        ( no, resume search)
    loop                           ( yes, continue comparing)
    if else drop drop i 4 pick + 0 ( if entire string is found)
    leave endif endif              ( then quit)
  loop rot drop rot drop rot drop  ( discard b addr2 and n2)
;