sspp

  Simple symbolic pre-processor
  reads from stdin, writes to stdout (also writes temporary file tmp.awk)
  Interprets simple definitions and evaluates numerical expressions with
  constants definitions.
  invoking sspp -nb produces a output file where all blank
  lines have been removed
 
  input file syntax:
   understands any C pre-processor commands (see man cpp)
   also understands #const [var1]=[value2]; [var2]=[value2]
   the variables var1 ... can be used later in the file.
   Expression to be evaluated must be enclosed in braces {}
   except when they are in a #const declaration.
   The brace characters are entered as \{ and \}
   Understands c++ comment char //

  Examples:
   #const x=2*3.14
   The value is {1+cos(x)}
   #define PLUS(x,y) ((x)+(y))
   The answer is {PLUS(1,2)}
   Braces are \{ \}

  Implementation details:
   Any line beginning with #const or #awk
   is interpreted as an awk command (see man awk).
   Expression in braces are awk expressions.
   The file tmp.awk is the file sent to awk for interpretation.

  BUGS

   Never start a line with %
   # is not a comment character