Index: fusl/src/math/logf.c |
diff --git a/fusl/src/math/logf.c b/fusl/src/math/logf.c |
new file mode 100644 |
index 0000000000000000000000000000000000000000..52230a1bd4dd6776fc55163729763766b589010e |
--- /dev/null |
+++ b/fusl/src/math/logf.c |
@@ -0,0 +1,69 @@ |
+/* origin: FreeBSD /usr/src/lib/msun/src/e_logf.c */ |
+/* |
+ * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. |
+ */ |
+/* |
+ * ==================================================== |
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
+ * |
+ * Developed at SunPro, a Sun Microsystems, Inc. business. |
+ * Permission to use, copy, modify, and distribute this |
+ * software is freely granted, provided that this notice |
+ * is preserved. |
+ * ==================================================== |
+ */ |
+ |
+#include <math.h> |
+#include <stdint.h> |
+ |
+static const float |
+ln2_hi = 6.9313812256e-01, /* 0x3f317180 */ |
+ln2_lo = 9.0580006145e-06, /* 0x3717f7d1 */ |
+/* |(log(1+s)-log(1-s))/s - Lg(s)| < 2**-34.24 (~[-4.95e-11, 4.97e-11]). */ |
+Lg1 = 0xaaaaaa.0p-24, /* 0.66666662693 */ |
+Lg2 = 0xccce13.0p-25, /* 0.40000972152 */ |
+Lg3 = 0x91e9ee.0p-25, /* 0.28498786688 */ |
+Lg4 = 0xf89e26.0p-26; /* 0.24279078841 */ |
+ |
+float logf(float x) |
+{ |
+ union {float f; uint32_t i;} u = {x}; |
+ float_t hfsq,f,s,z,R,w,t1,t2,dk; |
+ uint32_t ix; |
+ int k; |
+ |
+ ix = u.i; |
+ k = 0; |
+ if (ix < 0x00800000 || ix>>31) { /* x < 2**-126 */ |
+ if (ix<<1 == 0) |
+ return -1/(x*x); /* log(+-0)=-inf */ |
+ if (ix>>31) |
+ return (x-x)/0.0f; /* log(-#) = NaN */ |
+ /* subnormal number, scale up x */ |
+ k -= 25; |
+ x *= 0x1p25f; |
+ u.f = x; |
+ ix = u.i; |
+ } else if (ix >= 0x7f800000) { |
+ return x; |
+ } else if (ix == 0x3f800000) |
+ return 0; |
+ |
+ /* reduce x into [sqrt(2)/2, sqrt(2)] */ |
+ ix += 0x3f800000 - 0x3f3504f3; |
+ k += (int)(ix>>23) - 0x7f; |
+ ix = (ix&0x007fffff) + 0x3f3504f3; |
+ u.i = ix; |
+ x = u.f; |
+ |
+ f = x - 1.0f; |
+ s = f/(2.0f + f); |
+ z = s*s; |
+ w = z*z; |
+ t1= w*(Lg2+w*Lg4); |
+ t2= z*(Lg1+w*Lg3); |
+ R = t2 + t1; |
+ hfsq = 0.5f*f*f; |
+ dk = k; |
+ return s*(hfsq+R) + dk*ln2_lo - hfsq + f + dk*ln2_hi; |
+} |