1 files changed, 73 insertions, 0 deletions
diff --git a/lib/msun/src/s_cbrtf.c b/lib/msun/src/s_cbrtf.c
new file mode 100644
index 0000000..454f974
--- /dev/null
+++ b/lib/msun/src/s_cbrtf.c
@@ -0,0 +1,73 @@
+/* s_cbrtf.c -- float version of s_cbrt.c.
+ * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
+ * Debugged and optimized by Bruce D. Evans.
+ */
+
+/*
+ * ====================================================
+ * 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 <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include "math.h"
+#include "math_private.h"
+
+/* cbrtf(x)
+ * Return cube root of x
+ */
+static const unsigned
+	B1 = 709958130, /* B1 = (127-127.0/3-0.03306235651)*2**23 */
+	B2 = 642849266; /* B2 = (127-127.0/3-24/3-0.03306235651)*2**23 */
+
+float
+cbrtf(float x)
+{
+	double r,T;
+	float t;
+	int32_t hx;
+	u_int32_t sign;
+	u_int32_t high;
+
+	GET_FLOAT_WORD(hx,x);
+	sign=hx&0x80000000; 		/* sign= sign(x) */
+	hx  ^=sign;
+	if(hx>=0x7f800000) return(x+x); /* cbrt(NaN,INF) is itself */
+
+    /* rough cbrt to 5 bits */
+	if(hx<0x00800000) { 		/* zero or subnormal? */
+	    if(hx==0)
+		return(x);		/* cbrt(+-0) is itself */
+	    SET_FLOAT_WORD(t,0x4b800000); /* set t= 2**24 */
+	    t*=x;
+	    GET_FLOAT_WORD(high,t);
+	    SET_FLOAT_WORD(t,sign|((high&0x7fffffff)/3+B2));
+	} else
+	    SET_FLOAT_WORD(t,sign|(hx/3+B1));
+
+    /*
+     * First step Newton iteration (solving t*t-x/t == 0) to 16 bits.  In
+     * double precision so that its terms can be arranged for efficiency
+     * without causing overflow or underflow.
+     */
+	T=t;
+	r=T*T*T;
+	T=T*((double)x+x+r)/(x+r+r);
+
+    /*
+     * Second step Newton iteration to 47 bits.  In double precision for
+     * efficiency and accuracy.
+     */
+	r=T*T*T;
+	T=T*((double)x+x+r)/(x+r+r);
+
+    /* rounding to 24 bits is perfect in round-to-nearest mode */
+	return(T);
+}