\ double-arith.fs - Double-precision arithmetic extensions

\ Copyright 2013 David Meyer <papa@sdf.org> +JMJ

\ Copying and distribution of this file, with or without
\ modification, are permitted in any medium without royalty
\ provided the copyright notice and this notice are preserved.
\ This file is offered as-is, without any warranty.

\ MAXU - Maximum value of unsigned single
s" MAX-U" environment? drop constant MAXU

\ md* - Multiply double by unsigned single (iterative method)
: md* ( d u -- d*u )
    0. rot
    0 u+do 2over d+ loop
    2nip
;

\ mudu* - Multiply unsigned double by unsigned single
: mudu* ( ud u -- ud*u ) tuck * >r m* r> + ;

\ ud* - Multiply two unsigned doubles
: ud* ( ud1 ud2 -- ud1*ud2 )
    { a1 b1 a2 b2 } 
    a1 a2 um* 
    MAXU a1 um* b2 mudu* d+
    MAXU a2 um* b1 mudu* d+
    MAXU MAXU um* b1 mudu* b2 mudu* d+
;