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Diffstat (limited to 'test/src/data-tests.el')
| -rw-r--r-- | test/src/data-tests.el | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/test/src/data-tests.el b/test/src/data-tests.el index 8de8c145d40..374d1689b9e 100644 --- a/test/src/data-tests.el +++ b/test/src/data-tests.el @@ -107,6 +107,21 @@ (should (isnan (min 1.0 0.0e+NaN))) (should (isnan (min 1.0 0.0e+NaN 1.1)))) +(defun data-tests-popcnt (byte) + "Calculate the Hamming weight of BYTE." + (if (< byte 0) + (setq byte (lognot byte))) + (setq byte (- byte (logand (lsh byte -1) #x55555555))) + (setq byte (+ (logand byte #x33333333) (logand (lsh byte -2) #x33333333))) + (lsh (* (logand (+ byte (lsh byte -4)) #x0f0f0f0f) #x01010101) -24)) + +(ert-deftest data-tests-logcount () + (should (cl-loop for n in (number-sequence -255 255) + always (= (logcount n) (data-tests-popcnt n)))) + ;; https://oeis.org/A000120 + (should (= 11 (logcount 9727))) + (should (= 8 (logcount 9999)))) + ;; Bool vector tests. Compactly represent bool vectors as hex ;; strings. |