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authorUlrich Drepper <drepper@redhat.com>1999-07-14 00:54:57 +0000
committerUlrich Drepper <drepper@redhat.com>1999-07-14 00:54:57 +0000
commitabfbdde177c3a7155070dda1b2cdc8292054cc26 (patch)
treee021306b596381fbf8311d2b7eb294e918ff17c8 /sysdeps/ieee754/flt-32/e_log10f.c
parent86421aa57ecfd70963ae66848bd6a6dd3b8e0fe6 (diff)
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Update.
Diffstat (limited to 'sysdeps/ieee754/flt-32/e_log10f.c')
-rw-r--r--sysdeps/ieee754/flt-32/e_log10f.c67
1 files changed, 67 insertions, 0 deletions
diff --git a/sysdeps/ieee754/flt-32/e_log10f.c b/sysdeps/ieee754/flt-32/e_log10f.c
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+++ b/sysdeps/ieee754/flt-32/e_log10f.c
@@ -0,0 +1,67 @@
+/* e_log10f.c -- float version of e_log10.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.
+ * ====================================================
+ */
+
+#if defined(LIBM_SCCS) && !defined(lint)
+static char rcsid[] = "$NetBSD: e_log10f.c,v 1.5 1995/05/10 20:45:53 jtc Exp $";
+#endif
+
+#include "math.h"
+#include "math_private.h"
+
+#ifdef __STDC__
+static const float
+#else
+static float
+#endif
+two25      =  3.3554432000e+07, /* 0x4c000000 */
+ivln10     =  4.3429449201e-01, /* 0x3ede5bd9 */
+log10_2hi  =  3.0102920532e-01, /* 0x3e9a2080 */
+log10_2lo  =  7.9034151668e-07; /* 0x355427db */
+
+#ifdef __STDC__
+static const float zero   =  0.0;
+#else
+static float zero   =  0.0;
+#endif
+
+#ifdef __STDC__
+	float __ieee754_log10f(float x)
+#else
+	float __ieee754_log10f(x)
+	float x;
+#endif
+{
+	float y,z;
+	int32_t i,k,hx;
+
+	GET_FLOAT_WORD(hx,x);
+
+        k=0;
+        if (hx < 0x00800000) {			/* x < 2**-126  */
+            if ((hx&0x7fffffff)==0)
+                return -two25/(x-x);		/* log(+-0)=-inf */
+            if (hx<0) return (x-x)/(x-x);	/* log(-#) = NaN */
+            k -= 25; x *= two25; /* subnormal number, scale up x */
+	    GET_FLOAT_WORD(hx,x);
+        }
+	if (hx >= 0x7f800000) return x+x;
+	k += (hx>>23)-127;
+	i  = ((u_int32_t)k&0x80000000)>>31;
+        hx = (hx&0x007fffff)|((0x7f-i)<<23);
+        y  = (float)(k+i);
+	SET_FLOAT_WORD(x,hx);
+	z  = y*log10_2lo + ivln10*__ieee754_logf(x);
+	return  z+y*log10_2hi;
+}