Update of /project/ieeefp-tests/cvsroot/ieeefp-tests/ieee754 In directory common-lisp.net:/tmp/cvs-serv6045/ieee754

Modified Files: ieee754-cmucl.lisp Log Message: First pass at some of the IEEE754 recommended functions. Simple tests work, but still need to write a test-suite for these.

Date: Wed Jun 16 19:59:42 2004 Author: rtoy

Index: ieeefp-tests/ieee754/ieee754-cmucl.lisp diff -u ieeefp-tests/ieee754/ieee754-cmucl.lisp:1.1 ieeefp-tests/ieee754/ieee754-cmucl.lisp:1.2 --- ieeefp-tests/ieee754/ieee754-cmucl.lisp:1.1 Tue Jun 8 06:44:43 2004 +++ ieeefp-tests/ieee754/ieee754-cmucl.lisp Wed Jun 16 19:59:42 2004 @@ -30,3 +30,78 @@ precision)) (apply #'ext:set-floating-point-modes args))

+ +;;; IEEE754 recommended functions + +(defun copysign (x y) + "Copy the sign of Y to X and return the result" + (float-sign y x)) + +(defun scalb (x n) + "Compute x*2^n, without roundoff" + (scale-float x n)) + +(defun finitep (x) + "Returns non-NIL if X is a finite value" + ;; What are we supposed to do when X is a NaN? + (not (ext:float-infinity-p x))) + +(defun nanp (x) + "Returns non-NIL if X is a NaN" + (ext:float-nan-p x)) + +(defun logb (x) + "Return the unbiased exponent of X, except for the following: + + NaN NaN + +infinity +infinity + 0 -infinity, signaling division by zero + + Also, 0 < scalb(x, -logb(x)) < 2, when x is positive and finite; it + is less than 1 only when x is denormalized." + (cond ((nanp x) + x) + ((not (finitep x)) + x) + ((zerop x) + ;; Need to signal division by zero, if enabled; otherwise, + ;; return -infinity. + (/ -1 x)) + (t + ;; Finite x. DECODE-FLOAT is basically what we want, except + ;; it's one too big. And it's also too small for + ;; denormalized numbers. We need to clip at the least + ;; exponent for normalized floats. + (multiple-value-bind (f e s) + (decode-float x) + (declare (ignore f s)) + (max (1- e) + (etypecase x + (single-float -126) + (double-float -1022))))))) + +(defun nextafter (x y) + "The next double float after X in the direction of Y, with the +following exceptions: + + X = Y returns X, unchanged + X or Y is quiet NaN returns the NaN + + Overflow is signaled if nextafter would overflow; underflow is +signaled if nextafter would underflow. In both cases, inexact +is signaled." + + ;; What are we supposed to do if x or y is a signaling NaN? + (cond ((= x y) + x) + ((nanp x) + x) + ((nanp y) + y) + (t + (multiple-value-bind (f e s) + (integer-decode-float x) + (if (>= y 0) + (incf f) + (decf f)) + (* s (scale-float (float f x) e))))))