Programmer 7500/MAX_PROGRAMMERS.iso/CLIPPER/MISC/BIPL.ZIP/PROGS.ZIP/PRESS.ICN

Text File | 1993-01-27 | 25.0 KB | 893 lines

############################################################################
#
#    File:     press.icn
#
#    Subject:  Program to archive files
#
#    Author:   Robert J. Alexander
#
#    Date:     November 14, 1991
#
###########################################################################
#
#  Besides being a useful file archiving utility, this program can be
#  used to experiment with the LZW compression process, as it contains
#  extensive tracing facilities that illustrate the process in detail.
#
#  Compression can be turned off if faster archiving is desired.
#
#  The LZW compression procedures in this program are general purpose
#  and suitable for reuse in other programs.
#
############################################################################
#
#  Instructions for use are summarized in "help" procedures that follow.
#
############################################################################
#
#  Links: options, colmize, wildcard
#
############################################################################

link options, colmize, wildcard

procedure Usage(s)
   /s := ""
   stop("\nUsage:_
\n      Compress: press -c <archive file> [<options>] [<file to compress>...]_
\n      Archive:  press -a <archive file> [<options>] [<file to archive>...]_
\n      Extract:  press -x <archive file> [<options>] [<file to extract>...]_
\n      Print:    press -p <archive file> [<options>] [<file to print>...]_
\n      List:     press -l <archive file> [<options>] [<file to list>...]_
\n      Delete:   press -d <archive file> [<options>] <file to delete>..._
\n_
\n      Help:     press         (prints this message)_
\n      More help:press -h      (prints more details)_
\n_
\n      -c  perform compression into <archive file>_
\n      -a  add file(s) to <archive file> in uncompressed format_
\n      -x  extract (& decompress) file(s) from <archive file>_
\n      -p  extract (& decompress) from <archive file> to standard output_
\n      -l  list file names in <archive file>_
\n      -d  delete file(s) from <archive file>_
\n          (produces new file -- old file saved with \".bak\" suffix)_
\n_
\n      Options:_
\n      -q  work quietly_
\n      -t  text file(s) (retrieves with correct line end format)_
\n    -n  process all files in archive *except* specified files_
\n_
\n      LZW Experimentor Options:_
\n      -T  produce detailed compression trace info (to standard error file)_
\n      -S  maximum compression string table size_
\n          (for -c only -- default = 1024)_
\n"
      ,s)
end

procedure MoreHelp()
   return "\n _
  The archive (-a) option means to add the file without compression._
\n_
\n If no files are specified to extract, print, or list, then all files_
\n in the archive are used._
\n_
\n UNIX-style filename wildcard conventions can be used to express_
\n the archived file names for extract, print, list, and delete_
\n operations.  Be sure to quote names containing wildcard characters_
\n so that they aren't expanded by the shell (if applicable)._
\n_
\n If a <file to compress> or <file to archive> is \"-\", or if no files_
\n are specified, standard input is archived._
\n_
\n If <archive file> for extract, print, or list is \"-\", standard input_
\n is the archive file._
\n_
\n If <archive file> for compress or archive is \"-\", archive is written_
\n to standard output._
\n_
\n New files archived to an existing archive file are always appended,_
\n deleting any previously archived version of the same file name._
\n_
\n Archive files can be simply concatenated to create their union._
\n However, if the same file exists in both archives, only the first_
\n in the resulting file will be able to be accessed._
\n_
\n If a \"compressed\" file turns out to be longer than the uncompressed_
\n file (rare but possible, usually for very short files), the file will_
\n automatically be archived in uncompressed format._
\n_
\n A default file name suffix of \".prx\" is assumed for <archive file>_
\n names that are specified without a suffix._
\n_
\n_
\n LZW \"internals\" option:_
\n_
\n If the specified maximum table size is positive, the string table is_
\n discarded when the maximum size is reached and rebuilt (usually the_
\n better choice).  If negative, the original table is not discarded,_
\n which might produce better results in some circumstances.  This_
\n option was provided primarily for experimentors._
\n"
end

#
#  Global variables.
#
#  Note:  additional globals that contain option values are defined near
#  Options(), below.
#
global inchars,outchars,tinchars,toutchars,lzw_recycles,
      lzw_stringTable,rf,wf,magic,rline,wline

#
#  Main procedure.
#
procedure main(arg)
   local arcfile
   #
   #  Initialize.
   #
   Options(arg)
   inchars := outchars := tinchars := toutchars := lzw_recycles := 0
   magic := "\^p\^r\^e\^s\^s\^i\^c\^n"
   #
   #  Do requested operation.
   #
   arcfile :=
         DefaultSuffix(\(compr | archive | extract | print | lister | deleter),
         "prx") | Usage()
   if \(compr | archive) then Archive(arcfile,arg)
   else if \(extract | print) then Extract(arcfile,arg)
   else if \lister then List(arcfile,arg)
   else if \deleter then Delete(arcfile,arg)
   return
end


#
#  Option global variables.
#
global lzw_trace,maxTableSpecified,maxTableSize,print,quiet,tmode,WildMatch
global extract,compr,archive,lister,deleter

#
#  Options() -- Handle command line options.
#
procedure Options(arg)
   local opt,n,x
   opt := options(arg,"hc:a:x:p:l:d:qtTS+n")
   if \opt["h"] then Usage(MoreHelp())
   extract := opt["x"]
   print := opt["p"]
   compr := opt["c"]
   archive := opt["a"]
   lister := opt["l"]
   deleter := opt["d"]
   quiet := opt["q"]
   tmode := if \opt["t"] then "t" else "u"
   WildMatch := if \opt["n"] then not_wild_match else whole_wild_match
   lzw_trace := opt["T"]
   maxTableSpecified := opt["S"]
   maxTableSize := \maxTableSpecified | 1024    # 10 bits default
   n := 0
   every x := compr | archive | extract | print | lister | deleter do
         if \x then n +:= 1
   if n ~= 1 then Usage()
   return
end


#
#  Archive() -- Do archiving.
#
procedure Archive(arcfile,arg)
   local fn,addr,realLen,maxT,length,addr2,deleteFiles,new_data_start
   #
   #  Confirm options and open the archive file.
   #
   if *arg = 0 | WildMatch === not_wild_match then Usage()
   if ("" | "-") ~== arcfile then {
      if wf := open(arcfile,"ru") then {
         if not (reads(wf,*magic) == magic) then {
            stop("Invalid archive file ",arcfile)
            }
         close(wf)
         }
      wf := open(arcfile,"bu" | "wu") | stop("Can't open archive file ",arcfile)
      if tmode == "t" then rline := "\n"
      seek(wf,0)
      if where(wf) = 1 then writes(wf,magic)
      }
   else {
      wf := &output
      arcfile := "stdout"
      }
   new_data_start := where(wf)
   ## if /quiet then
   ##    write(&errout,"New data starting at byte ",new_data_start," of ",arcfile)
   #
   #  Loop to process files on command line.
   #
   if *arg = 0 then arg := ["-"]
   deleteFiles := []
   every fn := !arg do {
      if fn === arcfile then next
      if /quiet then
         writes(&errout,"File \"",fn,"\" -- ")
      rf := if fn ~== "-" then open(fn,tmode) | &null else &input
      if /rf then {
         if /quiet then
            write(&errout,"Can't open input file \"",fn,"\" -- skipped")
         next
         }
      put(deleteFiles,fn)
      WriteString(wf,Tail(fn))
      addr := where(rf)
      seek(rf,0)
      realLen := where(rf) - 1
      WriteInteger(wf,realLen)
      seek(rf,addr)
      if /quiet then
         writes(&errout,"Length: ",realLen)
      addr := where(wf)
      WriteInteger(wf,0)
      writes(wf,"\1")    # write a compression version string
      if \compr then {
         WriteInteger(wf,maxTableSize)
         maxT := Compress(R,W,maxTableSize)
         length := outchars + 4
         if /quiet then
            writes(&errout,"  Compressed: ",length,"  ",
                  Percent(realLen - outchars,realLen))
         }
      #
      #  If compressed file is larger than original, just copy the original.
      #
      if \archive | length > realLen then {
         if /quiet then
            writes(&errout," -- Archived uncompressed")
         seek(wf,addr + 4)
         writes(wf,"\0") # write a zero version string for uncompressed
         seek(rf,1)
         CopyFile(rf,wf)
         inchars := outchars := length := realLen
         maxT := 0
         lzw_stringTable := ""
         }
      if /quiet then
         write(&errout)
      close(rf)
      addr2 := where(wf)
      seek(wf,addr)
      WriteInteger(wf,length)
      seek(wf,addr2)
      if /quiet then
         Stats(maxT)
      }
   close(wf)
   if /quiet then
      if *arg > 1 then FinalStats()
   Delete(arcfile,deleteFiles,new_data_start)
   return
end


#
#  Extract() -- Extract a file from the archive.
#
procedure Extract(arcfile,arg)
   local fileSet,wfn,realLen,cmprLen,maxT,version,theArg
   if \maxTableSpecified then Usage()
   rf := OpenReadArchive(arcfile)
   arcfile := rf[2]
   rf := rf[1]
   if *arg > 0 then fileSet := set(arg)
   #
   #  Process input file.
   #
   while wfn := ReadString(rf) do {
      (realLen := ReadInteger(rf) &
            cmprLen := ReadInteger(rf) &
            version := ord(reads(rf))) |
            stop("Bad format in compressed file")
      if /quiet then
         writes(&errout,"File \"",wfn,"\" -- length: ",realLen,
               "  compressed: ",cmprLen," bytes -- ")
      if /fileSet | WildMatch(theArg := !arg,wfn) then {
         delete(\fileSet,theArg)
         if not version = (0 | 1) then {
         if /quiet then
               write(&errout,"can't handle this compression type (",version,
                     ") -- skipped")
            seek(rf,where(rf) + cmprLen)
            }
         else {
            if /quiet then
               write(&errout,"extracted")
            if /print then {
               wf := open(wfn,"w" || tmode) | &null
               if /wf then {
                  if /quiet then
                     write(&errout,"Can't open output file \"",wfn,
                           "\" -- quitting")
                  exit(1)
                  }
               }
            else wf := &output
            if version = 1 then {
               maxT := ReadInteger(rf) |
                     stop("Error in archive file format: ","table size missing")
               Decompress(R,W,maxT)
               }
            else {
               maxT := 0
               CopyFile(rf,wf,cmprLen)
               outchars := inchars := realLen
               }
            close(&output ~=== wf)
            if /quiet then
               Stats(maxT)
            }
         }
      else {
         if /quiet then
            write(&errout,"skipped")
         seek(rf,where(rf) + cmprLen)
         }
      }
   close(rf)
   FilesNotFound(fileSet)
   return
end


#
#  List() -- Skip through the archive, extracting info about files,
#  then list in columns.
#
procedure List(arcfile,arg)
   local fileSet,flist,wfn,realLen,cmprLen,version,theArg
   if \maxTableSpecified then Usage()
   rf := OpenReadArchive(arcfile)
   arcfile := rf[2]
   rf := rf[1]
   write(&errout,"Archive file ",arcfile,":")
   if *arg > 0 then fileSet := set(arg)
   #
   #  Process input file.
   #
   flist := []
   while wfn := ReadString(rf) do {
      (realLen := ReadInteger(rf) &
            cmprLen := ReadInteger(rf) &
            version := ord(reads(rf))) |
            stop("Bad format in compressed file")
      if /fileSet | WildMatch(theArg := !arg,wfn) then {
         delete(\fileSet,theArg)
         put(flist,"\"" || wfn || "\" " || realLen || "->" || cmprLen)
         tinchars +:= realLen
         toutchars +:= cmprLen
         }
      seek(rf,where(rf) + cmprLen)
      }
   close(rf)
   every write(&errout,colmize(sort(flist)))
   FilesNotFound(fileSet)
   FinalStats()
   return
end


#
#  Delete() -- Delete a file from the archive.
#
procedure Delete(arcfile,arg,new_data_start)
   local workfn,workf,fileSet,wfn,realLen,cmprLen,bakfn,deletedFiles,
         head,version,hdrLen,theArg
   if *arg = 0 | (\deleter & \maxTableSpecified) then Usage()
   rf := OpenReadArchive(arcfile)
   arcfile := rf[2]
   rf := rf[1]
   workfn := Root(arcfile) || ".wrk"
   workf := open(workfn,"wu") | stop("Can't open work file ",workfn)
   writes(workf,magic)
   fileSet := set(arg)
   #
   #  Process input file.
   #
   deletedFiles := 0
   head := if \deleter then "File" else "Replaced file"
   while not (\new_data_start <= where(rf)) & wfn := ReadString(rf) do {
      (realLen := ReadInteger(rf) &
            cmprLen := ReadInteger(rf) &
            version := ord(reads(rf))) |
            stop("Bad format in compressed file")
      if /quiet then
         writes(&errout,head," \"",wfn,"\" -- length: ",realLen,
               "  compressed: ",cmprLen," bytes -- ")
      if WildMatch(theArg := !arg,wfn) then {
         deletedFiles +:= 1
         delete(fileSet,theArg)
         if /quiet then
            write(&errout,"deleted")
         seek(rf,where(rf) + cmprLen)
         }
      else {
         if /quiet then
            write(&errout,"kept")
         hdrLen := *wfn + 10
         seek(rf,where(rf) - hdrLen)
         CopyFile(rf,workf,cmprLen + hdrLen)
         }
      }
   if deletedFiles > 0 then {
      CopyFile(rf,workf)
      every close(workf | rf)
      if (rf ~=== &input) then {
         bakfn := Root(arcfile) || ".bak"
         remove(bakfn)
         rename(arcfile,bakfn) | stop("Couldn't rename ",arcfile," to ",bakfn)
         }
      rename(workfn,arcfile) | stop("Couldn't rename ",workfn," to ",arcfile)
      }
   else {
      every close(workf | rf)
      remove(workfn)
      }
   if \deleter then FilesNotFound(fileSet)
   return
end


#
#  OpenReadArchive() -- Open an archive for reading.
#
procedure OpenReadArchive(arcfile)
   local rf
   rf := if ("" | "-") ~== arcfile then
         open(arcfile,"ru") | stop("Can't open archive file ",arcfile)
   else {
      arcfile := "stdin"
      &input
      }
   if reads(rf,*magic) ~== magic then stop("Invalid archive file ",arcfile)
   if tmode == "t" then wline := "\x0a"
   return [rf,arcfile]
end


#
#  FilesNotFound() -- List the files remaining in "fileSet".
#
procedure FilesNotFound(fileSet)
   return if *\fileSet > 0 then {
      write(&errout,"\nFiles not found:")
      every write(&errout," ",colmize(sort(fileSet),78))
      &null
      }
end


#
#  Stats() -- Print stats after a file.
#
procedure Stats(maxTableSize)
   #
   #  Write statistics
   #
   if \lzw_trace then write(&errout,
         "  table size = ",*lzw_stringTable,"/",maxTableSize,
         " (recycles: ",lzw_recycles,")")
   tinchars +:= inchars
   toutchars +:= outchars
   inchars := outchars := lzw_recycles := 0
   return
end


#
#  FinalStats() -- Print final stats.
#
procedure FinalStats()
   #
   #  Write final statistics
   #
   write(&errout,"\nTotals: ",
         "\n  input: ",tinchars,
         "\n  output: ",toutchars,
         "\n  compression: ",Percent(tinchars - toutchars,tinchars) | "",
         "\n")
   return
end


#
#  WriteInteger() -- Write a 4-byte binary integer to "f".
#
procedure WriteInteger(f,i)
   local s
   s := ""
   every 1 to 4 do {
      s := char(i % 256) || s
      i /:= 256
      }
   return writes(f,s)
end


#
#  ReadInteger() -- Read a 4-byte binary integer from "f".
#
procedure ReadInteger(f)
   local s,v
   s := reads(f,4) | fail
   if *s < 4 then
         stop("Error in archive file format: ","bad integer")
   v := 0
   s ? while v := v * 256 + ord(move(1))
   return v
end


#
#  WriteString() -- Write a string preceded by a length byte to "f".
#
procedure WriteString(f,s)
   return writes(f,char(*s),s)
end


#
#  ReadString() -- Read a string preceded by a length byte from "f".
#
procedure ReadString(f)
   local len,s
   len := ord(reads(f)) | fail
   s := reads(f,len)
   if *s < len then
         stop("Error in archive file format: ","bad string")
   return s
end


#
#  CopyFile() -- Copy a file.
#
procedure CopyFile(rf,wf,len)
   local s
   if /len then {
      while writes(wf,s := reads(rf,1000))
      }
   else {
      while len > 1000 & writes(wf,s := reads(rf,1000)) do len -:= *s
      writes(wf,s := reads(rf,len)) & len -:= *s
      }
   return len
end


#
#  Percent() -- Format a rational number "n"/"d" as a percentage.
#
procedure Percent(n,d)
   local sign,whole,fraction
   n / (0.0 ~= d) ? {
      sign := ="-" | ""
      whole := tab(find("."))
      move(1)
      fraction := tab(0)
      }
   return (\sign || ("0" ~== whole | "") ||
         (if whole == "0" then integer else 1)(left(fraction,2,"0")) | "--") ||
         "%"
end


#
#  R() -- Read-a-character procedure.
#
procedure R()
   local c

   c := reads(rf) | fail
   inchars +:= 1
   if c === rline then c := "\x0a"
   return c
end


#
#  W() -- Write-characters procedure.
#
procedure W(s)
   local i

   every i := find(\wline,s) do s[i] := "\n"
   outchars +:= *s
   return writes(wf,s)
end


#
#  Tail() -- Return the file name portion (minus the path) of a
#  qualified file name.
#
procedure Tail(fn)
   local i
   i := 0
   every i := upto('/\\:',fn)
   return .fn[i + 1:0]
end


#
#  Root() -- Return the root portion (minus the suffix) of a file name.
#
procedure Root(fn)
   local i
   i := 0
   every i := find(".",fn)
   return .fn[1:i]
end


procedure DefaultSuffix(fn,suf)
   local i
   return fn || "." || suf
end


############################################################################
#
#  Compress() -- LZW compression
#
#  Arguments:
#
#       inproc  a procedure that returns a single character from
#               the input stream.
#
#       outproc a procedure that writes a single character (its
#               argument) to the output stream.
#
#       maxTableSize    the maximum size to which the string table
#               is allowed to grow before something is done about it.
#               If the size is positive, the table is discarded and
#               a new one started.  If negative, it is retained, but
#               no new entries are added.
#

procedure Compress(inproc,outproc,maxTableSize)
   local EOF,c,charTable,junk1,junk2,outcode,s,t,tossTable,x
   #
   #  Initialize.
   #
   /maxTableSize := 1024        # default 10 "bits"
   tossTable := maxTableSize
   /lzw_recycles := 0
   if maxTableSize < 0 then maxTableSize := -maxTableSize
   charTable := table()
   every c := !&cset do charTable[c] := ord(c)
   EOF := charTable[*charTable] := *charTable    # reserve code=256 for EOF
   lzw_stringTable := copy(charTable)
   #
   #  Compress the input stream.
   #
   s := inproc() | return maxTableSize
   if \lzw_trace then {
      write(&errout,"\nInput string\tOutput code\tNew table entry")
      writes(&errout,"\"",image(s)[2:-1])
      }
   while c := inproc() do {
      if \lzw_trace then
            writes(&errout,image(c)[2:-1])
      if \lzw_stringTable[t := s || c] then s := t
      else {
         Compress_output(outproc,junk2 := lzw_stringTable[s],
               junk1 := *lzw_stringTable)
         if *lzw_stringTable < maxTableSize then
               lzw_stringTable[t] := *lzw_stringTable
         else if tossTable >= 0 then {
               lzw_stringTable := copy(charTable)
               lzw_recycles +:= 1
            }
         if \lzw_trace then
               writes(&errout,"\"\t\t",
                     image(char(*&cset > junk2) | junk2),
                     "(",junk1,")\t\t",lzw_stringTable[t]," = ",image(t),"\n\"")
         s := c
         }
      }
      Compress_output(outproc,junk2 := lzw_stringTable[s],
        junk1 := *lzw_stringTable)
      if *lzw_stringTable < maxTableSize then
        {}
      else if tossTable >= 0 then {
        lzw_stringTable := copy(charTable)
        lzw_recycles +:= 1
     }
      if \lzw_trace then
        writes(&errout,"\"\t\t",
          image(char(*&cset > junk2) | junk2),"(",junk1,")\n")
   Compress_output(outproc,EOF,*lzw_stringTable)
   if \lzw_trace then write(&errout,"\"\t\t",EOF)
   Compress_output(outproc)
   return maxTableSize
end


procedure Compress_output(outproc,code,stringTableSize)
   local outcode
   static max,bits,buffer,bufferbits,lastSize
   #
   #  Initialize.
   #
   initial {
      lastSize := 1000000
      buffer := bufferbits := 0
      }
   #
   #  If this is "close" call, flush buffer and reinitialize.
   #
   if /code then {
      outcode := &null
      if bufferbits > 0 then
            outproc(char(outcode := ishift(buffer,8 - bufferbits)))
      lastSize := 1000000
      buffer := bufferbits := 0
      return outcode
      }
   #
   #  Expand output code size if necessary.
   #
   if stringTableSize < lastSize then {
      max := 1
      bits := 0
      }
   while stringTableSize > max do {
      max *:= 2
      bits +:= 1
      }
   lastSize := stringTableSize
   #
   #  Merge new code into buffer.
   #
   buffer := ior(ishift(buffer,bits),code)
   bufferbits +:= bits
   #
   #  Output bits.
   #
   while bufferbits >= 8 do {
      outproc(char(outcode := ishift(buffer,8 - bufferbits)))
      buffer := ixor(buffer,ishift(outcode,bufferbits - 8))
      bufferbits -:= 8
      }
   return outcode
end


############################################################################
#
#  Decompress() -- LZW decompression of compressed stream created
#                  by Compress()
#
#  Arguments:
#
#       inproc  a procedure that returns a single character from
#               the input stream.
#
#       outproc a procedure that writes a single character (its
#               argument) to the output stream.
#

procedure Decompress(inproc,outproc,maxTableSize)
   local EOF,c,charSize,code,i,new_code,old_strg,
         strg,tossTable
   #
   #  Initialize.
   #
   /maxTableSize := 1024        # default 10 "bits"
   tossTable := maxTableSize
   /lzw_recycles := 0
   if maxTableSize < 0 then maxTableSize := -maxTableSize
   maxTableSize -:= 1
   lzw_stringTable := list(*&cset)
   every i := 1 to *lzw_stringTable do lzw_stringTable[i] := char(i - 1)
   put(lzw_stringTable,EOF := *lzw_stringTable)  # reserve code=256 for EOF
   charSize := *lzw_stringTable
   if \lzw_trace then
         write(&errout,"\nInput code\tOutput string\tNew table entry")
   #
   #  Decompress the input stream.
   #
   while old_strg :=
         lzw_stringTable[Decompress_read_code(inproc,
         *lzw_stringTable,EOF) + 1] do {
      if \lzw_trace then
            write(&errout,image(old_strg),"(",*lzw_stringTable,")",
                  "\t",image(old_strg))
      outproc(old_strg)
      c := old_strg[1]
      (while new_code := Decompress_read_code(inproc,
            *lzw_stringTable + 1,EOF) do {
         strg := lzw_stringTable[new_code + 1] | old_strg || c
         outproc(strg)
         c := strg[1]
         if \lzw_trace then
               write(&errout,image(char(*&cset > new_code) \ 1 | new_code),
                     "(",*lzw_stringTable + 1,")","\t",
                     image(strg),"\t\t",
                     *lzw_stringTable," = ",image(old_strg || c))
         if *lzw_stringTable < maxTableSize then
               put(lzw_stringTable,old_strg || c)
         else if tossTable >= 0 then {
            lzw_stringTable := lzw_stringTable[1:charSize + 1]
            lzw_recycles +:= 1
            break
            }
         old_strg := strg
         }) | break  # exit outer loop if this loop completed
      }
   Decompress_read_code()
   return maxTableSize
end


procedure Decompress_read_code(inproc,stringTableSize,EOF)
   local code
   static max,bits,buffer,bufferbits,lastSize

   #
   #  Initialize.
   #
   initial {
      lastSize := 1000000
      buffer := bufferbits := 0
      }
   #
   #  Reinitialize if called with no arguments.
   #
   if /inproc then {
      lastSize := 1000000
      buffer := bufferbits := 0
      return
      }
   #
   #  Expand code size if necessary.
   #
   if stringTableSize < lastSize then {
      max := 1
      bits := 0
      }
   while stringTableSize > max do {
      max *:= 2
      bits +:= 1
      }
   #
   #  Read in more data if necessary.
   #
   while bufferbits < bits do {
      buffer := ior(ishift(buffer,8),ord(inproc())) |
            stop("Premature end of file")
      bufferbits +:= 8
      }
   #
   #  Extract code from buffer and return.
   #
   code := ishift(buffer,bits - bufferbits)
   buffer := ixor(buffer,ishift(code,bufferbits - bits))
   bufferbits -:= bits
   return EOF ~= code
end


procedure whole_wild_match(p,s)
   return wild_match(p,s) > *s
end


procedure not_wild_match(p,s)
   return not (wild_match(p,s) > *s)
end