1 files changed, 51 insertions, 0 deletions
diff --git a/src/math/e_log10f.c b/src/math/e_log10f.c
new file mode 100644
index 00000000..8fc5c5ca
--- /dev/null
+++ b/src/math/e_log10f.c
@@ -0,0 +1,51 @@
+/* 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;
+}