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-rw-r--r--src/math/e_log10f.c51
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diff --git a/src/math/e_log10f.c b/src/math/e_log10f.c
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+/* 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.
+ * ====================================================
+ */
+
+#include <math.h>
+#include "math_private.h"
+
+static const float
+two25 = 3.3554432000e+07, /* 0x4c000000 */
+ivln10 = 4.3429449201e-01, /* 0x3ede5bd9 */
+log10_2hi = 3.0102920532e-01, /* 0x3e9a2080 */
+log10_2lo = 7.9034151668e-07; /* 0x355427db */
+
+static const float zero = 0.0;
+
+float
+log10f(float x)
+{
+ 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/zero; /* log(+-0)=-inf */
+ if (hx<0) return (x-x)/zero; /* 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 = ((uint32_t)k&0x80000000)>>31;
+ hx = (hx&0x007fffff)|((0x7f-i)<<23);
+ y = (float)(k+i);
+ SET_FLOAT_WORD(x,hx);
+ z = y*log10_2lo + ivln10*logf(x);
+ return z+y*log10_2hi;
+}