1 files changed, 60 insertions, 0 deletions
diff --git a/lib/msun/src/e_log2.c b/lib/msun/src/e_log2.c
new file mode 100644
index 0000000..6cf3dbc
--- /dev/null
+++ b/lib/msun/src/e_log2.c
@@ -0,0 +1,60 @@
+
+/* @(#)e_log10.c 1.3 95/01/18 */
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunSoft, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice 
+ * is preserved.
+ * ====================================================
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+/*
+ * Return the base 2 logarithm of x. See k_log.c for details on the algorithm.
+ */
+
+#include "math.h"
+#include "math_private.h"
+#include "k_log.h"
+
+static const double
+two54      =  1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */
+ivln2hi    =  1.44269504072144627571e+00, /* 0x3ff71547, 0x65200000 */
+ivln2lo    =  1.67517131648865118353e-10; /* 0x3de705fc, 0x2eefa200 */
+
+static const double zero   =  0.0;
+
+double
+__ieee754_log2(double x)
+{
+	double f,hi,lo;
+	int32_t i,k,hx;
+	u_int32_t lx;
+
+	EXTRACT_WORDS(hx,lx,x);
+
+        k=0;
+        if (hx < 0x00100000) {                  /* x < 2**-1022  */
+            if (((hx&0x7fffffff)|lx)==0)
+                return -two54/zero;             /* log(+-0)=-inf */
+            if (hx<0) return (x-x)/zero;        /* log(-#) = NaN */
+            k -= 54; x *= two54; /* subnormal number, scale up x */
+	    GET_HIGH_WORD(hx,x);
+        }
+	if (hx >= 0x7ff00000) return x+x;
+	k += (hx>>20)-1023;
+	hx &= 0x000fffff;
+	i = (hx+0x95f64)&0x100000;
+	SET_HIGH_WORD(x,hx|(i^0x3ff00000));	/* normalize x or x/2 */
+	k += (i>>20);
+	f = __kernel_log(x);
+	hi = x = x - 1;
+	SET_LOW_WORD(hi,0);
+	lo = x - hi;
+	return (x+f)*ivln2lo + (lo+f)*ivln2hi + hi*ivln2hi + k;
+}