/fth/math.fth

\ @(#) math.fth 98/01/26 1.2

\ Extended Math routines

\ FM/MOD SM/REM

\

\ Author: Phil Burk

\ Copyright 1994 3DO, Phil Burk, Larry Polansky, Devid Rosenboom

\

\ The pForth software code is dedicated to the public domain,

\ and any third party may reproduce, distribute and modify

\ the pForth software code or any derivative works thereof

\ without any compensation or license.  The pForth software

\ code is provided on an "as is" basis without any warranty

\ of any kind, including, without limitation, the implied

\ warranties of merchantability and fitness for a particular

\ purpose and their equivalents under the laws of any jurisdiction.



anew task-math.fth

decimal



: FM/MOD { dl dh nn | dlp dhp nnp rem quo -- rem quo , floored }

	dl dh dabs -> dhp -> dlp

	nn abs -> nnp

	dlp dhp nnp um/mod -> quo -> rem

	dh 0<  

	IF  \ negative dividend

		nn 0< 

		IF   \ negative divisor

			rem negate -> rem

		ELSE  \ positive divisor

			rem 0=

			IF

				quo negate -> quo

			ELSE

				quo 1+ negate -> quo

				nnp rem - -> rem

			THEN

		THEN

	ELSE  \ positive dividend

		nn 0<  

		IF  \ negative divisor

			rem 0=

			IF

				quo negate -> quo

			ELSE

				nnp rem - negate -> rem

				quo 1+ negate -> quo

			THEN

		THEN

	THEN

	rem quo

;



: SM/REM { dl dh nn | dlp dhp nnp rem quo -- rem quo , symmetric }

	dl dh dabs -> dhp -> dlp

	nn abs -> nnp

	dlp dhp nnp um/mod -> quo -> rem

	dh 0<  

	IF  \ negative dividend

		rem negate -> rem

		nn 0> 

		IF   \ positive divisor

			quo negate -> quo

		THEN

	ELSE  \ positive dividend

		nn 0<  

		IF  \ negative divisor

			quo negate -> quo

		THEN

	THEN

	rem quo

;





: /MOD ( a b -- rem quo )

	>r s>d r> sm/rem

;



: MOD ( a b -- rem )

	/mod drop

;



: */MOD ( a b c -- rem a*b/c , use double precision intermediate value )

	>r m*

	r> sm/rem

;

: */ ( a b c -- a*b/c , use double precision intermediate value )

	*/mod

	nip

;