(numerator divisor))))
(values q (- number (* q divisor)))))
((fixnum bignum)
- (values 0 number))
+ (bignum-truncate (make-small-bignum number) divisor))
((ratio (or float rational))
(let ((q (truncate (numerator number)
(* (denominator number) divisor))))
(if (eql divisor 1)
(round number)
(multiple-value-bind (tru rem) (truncate number divisor)
- (let ((thresh (/ (abs divisor) 2)))
- (cond ((or (> rem thresh)
- (and (= rem thresh) (oddp tru)))
- (if (minusp divisor)
- (values (- tru 1) (+ rem divisor))
- (values (+ tru 1) (- rem divisor))))
- ((let ((-thresh (- thresh)))
- (or (< rem -thresh)
- (and (= rem -thresh) (oddp tru))))
- (if (minusp divisor)
- (values (+ tru 1) (- rem divisor))
- (values (- tru 1) (+ rem divisor))))
- (t (values tru rem)))))))
+ (if (zerop rem)
+ (values tru rem)
+ (let ((thresh (/ (abs divisor) 2)))
+ (cond ((or (> rem thresh)
+ (and (= rem thresh) (oddp tru)))
+ (if (minusp divisor)
+ (values (- tru 1) (+ rem divisor))
+ (values (+ tru 1) (- rem divisor))))
+ ((let ((-thresh (- thresh)))
+ (or (< rem -thresh)
+ (and (= rem -thresh) (oddp tru))))
+ (if (minusp divisor)
+ (values (+ tru 1) (- rem divisor))
+ (values (- tru 1) (+ rem divisor))))
+ (t (values tru rem))))))))
(defun rem (number divisor)
#!+sb-doc
(def minusp "Is this real number strictly negative?")
(def oddp "Is this integer odd?")
(def evenp "Is this integer even?"))
+\f
+;;;; modular functions
+#.
+(collect ((forms))
+ (flet ((definition (name lambda-list width pattern)
+ ;; We rely on (SUBTYPEP `(UNSIGNED-BYTE ,WIDTH)
+ ;; 'BIGNUM-ELEMENT-TYPE)
+ `(defun ,name ,lambda-list
+ (flet ((prepare-argument (x)
+ (declare (integer x))
+ (etypecase x
+ ((unsigned-byte ,width) x)
+ (bignum-element-type (logand x ,pattern))
+ (fixnum (logand x ,pattern))
+ (bignum (logand (%bignum-ref x 0) ,pattern)))))
+ (,name ,@(loop for arg in lambda-list
+ collect `(prepare-argument ,arg)))))))
+ (loop for infos being each hash-value of sb!c::*modular-funs*
+ ;; FIXME: We need to process only "toplevel" functions
+ unless (eq infos :good)
+ do (loop for info in infos
+ for name = (sb!c::modular-fun-info-name info)
+ and width = (sb!c::modular-fun-info-width info)
+ and lambda-list = (sb!c::modular-fun-info-lambda-list info)
+ for pattern = (1- (ash 1 width))
+ do (forms (definition name lambda-list width pattern)))))
+ `(progn ,@(forms)))