(declare (type single-float x))
(assert (= (float-radix x) 2))
(if (zerop x)
- 0 ; known property of IEEE floating point: 0.0 is represented as 0.
+ (if (eql x 0.0f0) 0 #x-80000000)
(multiple-value-bind (lisp-significand lisp-exponent lisp-sign)
(integer-decode-float x)
(assert (plusp lisp-significand))
(if (plusp exponent) ; if not obviously denormalized
(do ()
(nil)
- (cond (;; ordinary termination case
+ (cond (;; special termination case, denormalized
+ ;; float number
+ (zerop exponent)
+ ;; Denormalized numbers have exponent one
+ ;; greater than the exponent field.
+ (return (ash significand -1)))
+ (;; ordinary termination case
(>= significand (expt 2 23))
(assert (< 0 significand (expt 2 24)))
;; Exponent 0 is reserved for
(return (logior (ash exponent 23)
(logand significand
(1- (ash 1 23))))))
- (;; special termination case, denormalized
- ;; float number
- (zerop exponent)
- ;; Denormalized numbers have exponent one
- ;; greater than the exponent field.
- (return (ash significand -1)))
+
(t
;; Shift as necessary to set bit 24 of
;; significand.
(ecase lisp-sign
(1 unsigned-result)
(-1 (logior unsigned-result (- (expt 2 31)))))))))
+
(defun double-float-bits (x)
(declare (type double-float x))
(assert (= (float-radix x) 2))
(if (zerop x)
- 0 ; known property of IEEE floating point: 0.0d0 is represented as 0.
+ (if (eql x 0.0d0) 0 #x-8000000000000000)
;; KLUDGE: As per comments in SINGLE-FLOAT-BITS, above.
(multiple-value-bind (lisp-significand lisp-exponent lisp-sign)
(integer-decode-float x)
(if (plusp exponent) ; if not obviously denormalized
(do ()
(nil)
- (cond (;; ordinary termination case
+ (cond (;; special termination case, denormalized
+ ;; float number
+ (zerop exponent)
+ ;; Denormalized numbers have exponent one
+ ;; greater than the exponent field.
+ (return (ash significand -1)))
+ (;; ordinary termination case
(>= significand (expt 2 52))
(assert (< 0 significand (expt 2 53)))
;; Exponent 0 is reserved for
(return (logior (ash exponent 52)
(logand significand
(1- (ash 1 52))))))
- (;; special termination case, denormalized
- ;; float number
- (zerop exponent)
- ;; Denormalized numbers have exponent one
- ;; greater than the exponent field.
- (return (ash significand -1)))
(t
;; Shift as necessary to set bit 53 of
;; significand.
(ecase lisp-sign
(1 unsigned-result)
(-1 (logior unsigned-result (- (expt 2 63)))))))))
+
(defun double-float-low-bits (x)
(declare (type double-float x))
(if (zerop x)
;; would be nice to make the family of functions have a more
;; consistent return convention.
(logand #xffffffff (double-float-bits x))))
+
(defun double-float-high-bits (x)
(declare (type double-float x))
(if (zerop x)
- 0
+ (if (eql x 0.0d0) 0 #x-80000000)
(mask-and-sign-extend (ash (double-float-bits x) -32) 32)))
;;; KLUDGE: This is a hack to work around a bug in CMU CL 18c which
;;; when trying to optimize the EXPT forms in the MAKE-FOO-FLOAT
;;; functions below. See the message
;;; Subject: Re: Compiler bug?
-;;; From: Raymond Toy <toy@rtp.ericsson.se>
+;;; From: Raymond Toy
;;; Date: 28 Mar 2001 08:19:59 -0500
-;;; Message-ID: <4nvgou3u9s.fsf@rtp.ericsson.se>
-;;; on the cmucl-imp@cons.org mailing list. Once the CMU CL folks
+;;; on the cmucl-imp mailing list. Once the CMU CL folks
;;; make a bug-fix release, we can get rid of this and go back to
;;; calling EXPT directly. -- WHN 2001-04-05
(defun kludge-opaque-expt (x y)
;;; workarounds *do* look messy to me, which is why I just went
;;; with this quick kludge instead.) -- WHN 19990711
(defun make-single-float (bits)
- (if (zerop bits) ; IEEE float special case
- 0.0
- (let ((sign (ecase (ldb (byte 1 31) bits)
- (0 1.0)
- (1 -1.0)))
- (expt (- (ldb (byte 8 23) bits) 127))
- (mant (* (logior (ldb (byte 23 0) bits)
- (ash 1 23))
- (expt 0.5 23))))
- (* sign (kludge-opaque-expt 2.0 expt) mant))))
+ (cond
+ ;; IEEE float special cases
+ ((zerop bits) 0.0)
+ ((= bits #x-80000000) -0.0)
+ (t (let* ((sign (ecase (ldb (byte 1 31) bits)
+ (0 1.0)
+ (1 -1.0)))
+ (iexpt (ldb (byte 8 23) bits))
+ (expt (if (zerop iexpt) ; denormalized
+ -126
+ (- iexpt 127)))
+ (mant (* (logior (ldb (byte 23 0) bits)
+ (if (zerop iexpt)
+ 0
+ (ash 1 23)))
+ (expt 0.5 23))))
+ (* sign (kludge-opaque-expt 2.0 expt) mant)))))
+
(defun make-double-float (hi lo)
- (if (and (zerop hi) (zerop lo)) ; IEEE float special case
- 0.0d0
- (let* ((bits (logior (ash hi 32) lo))
- (sign (ecase (ldb (byte 1 63) bits)
- (0 1.0d0)
- (1 -1.0d0)))
- (expt (- (ldb (byte 11 52) bits) 1023))
- (mant (* (logior (ldb (byte 52 0) bits)
- (ash 1 52))
- (expt 0.5d0 52))))
- (* sign (kludge-opaque-expt 2.0d0 expt) mant))))
+ (cond
+ ;; IEEE float special cases
+ ((and (zerop hi) (zerop lo)) 0.0d0)
+ ((and (= hi #x-80000000) (zerop lo)) -0.0d0)
+ (t (let* ((bits (logior (ash hi 32) lo))
+ (sign (ecase (ldb (byte 1 63) bits)
+ (0 1.0d0)
+ (1 -1.0d0)))
+ (iexpt (ldb (byte 11 52) bits))
+ (expt (if (zerop iexpt) ; denormalized
+ -1022
+ (- iexpt 1023)))
+ (mant (* (logior (ldb (byte 52 0) bits)
+ (if (zerop iexpt)
+ 0
+ (ash 1 52)))
+ (expt 0.5d0 52))))
+ (* sign (kludge-opaque-expt 2.0d0 expt) mant)))))
+
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