log2f
float log2f(float);
ATF_CHECK_EQ(i, log2f(ldexpf(1.0, i)));
test(log2f, 1.0, 0.0, ALL_STD_EXCEPT, 0);
test_tol(log2f, tests[i].x, tests[i].log2x, FLT_ULP());
test(log2f, x, result, exceptmask, excepts); \