Faster ISQRT on small (about fixnum sized) numbers.

[sbcl.git] / tests / arith.pure.lisp

diff --git a/tests/arith.pure.lisp b/tests/arith.pure.lisp
index e6543e7..c78b328 100644 (file)
--- a/tests/arith.pure.lisp
+++ b/tests/arith.pure.lisp
@@ -371,8 +371,12 @@
 ;; GCD used to sometimes return negative values. The following did, on 32 bit
 ;; builds.
 (with-test (:name :gcd)
+  ;; from lp#413680
   (assert (plusp (gcd 20286123923750474264166990598656
-                      680564733841876926926749214863536422912))))
+                      680564733841876926926749214863536422912)))
+  ;; from lp#516750
+  (assert (plusp (gcd 2596102012663483082521318626691873
+                      2596148429267413814265248164610048))))
 
 (with-test (:name :expt-zero-zero)
   ;; Check that (expt 0.0 0.0) and (expt 0 0.0) signal error, but (expt 0.0 0)
@@ -555,3 +559,30 @@
                             (declare (type (integer -3 57216651) a))
                             (ldb (byte 9 27) a)))))
     (assert (= 0 (- (funcall one 10) (funcall two 10))))))
+
+;; The ISQRT implementation is sufficiently complicated that it should
+;; be tested.
+(with-test (:name :isqrt)
+  (labels ((test (x)
+             (let* ((r (isqrt x))
+                    (r2 (expt r 2))
+                    (s2 (expt (1+ r) 2)))
+               (unless (and (<= r2 x)
+                            (> s2 x))
+                 (error "isqrt failure for ~a" x))))
+           (tests (x)
+             (test x)
+             (let ((x2 (expt x 2)))
+               (test x2)
+               (test (1+ x2))
+               (test (1- x2)))))
+    (test most-positive-fixnum)
+    (test (1+ most-positive-fixnum))
+    (loop for i from 1 to 200
+          for pow = (expt 2 (1- i))
+          for j = (+ pow (random pow))
+          do
+          (tests i)
+          (tests j))
+    (dotimes (i 10)
+      (tests (random (expt 2 (+ 1000 (random 10000))))))))