[no subject]

[JONL at MIT-MC (Jon L White)]

    Date: 18 September 1980 16:02-EDT
    From: Alan Bawden <ALAN at MIT-MC>
    Subject: (LDB 0203 Y) versus (LDB X Y)
    .  .  .
    (ldb 0203 y) expands into (boole 1 (lsh y -2) 7)
    (ldb x y)    expands into (*ldb (lsh x 30) y)
    I don't see anything that looks like (*ldb ppss_30 ...) 
    so I don't see
    how anything has been saved.
Are you asleep today!  How do you think the "7" got generated in the line
    "(ldb 0203 y) expands into (boole 1 (lsh y -2) 7)"
*LDB is not a user-available function -- it exists only as a stop-gap
until the compiler open-codes LDB.  (Although it is true now that *LDB is 
never handed a "constant" arg, that's not how it was when *LDB was first 
coded -- the conversion to BOOLE is a recent innovation -- but the whole 
existence of *LDB depends on whether or not the compiler knows how to 
open-code LDB).  Anyway, why are you worrying about this -- is it slowing 
your program down by 0.25%?