1 files changed, 54 insertions, 0 deletions
diff --git a/src/math/scalbnf.c b/src/math/scalbnf.c
new file mode 100644
index 00000000..0a6168b0
--- /dev/null
+++ b/src/math/scalbnf.c
@@ -0,0 +1,54 @@
+/* origin: FreeBSD /usr/src/lib/msun/src/s_scalbnf.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 "libm.h"
+
+static const float
+two25  = 3.355443200e+07,  /* 0x4c000000 */
+twom25 = 2.9802322388e-08, /* 0x33000000 */
+huge   = 1.0e+30,
+tiny   = 1.0e-30;
+
+float scalbnf(float x, int n)
+{
+	int32_t k, ix;
+	GET_FLOAT_WORD(ix, x);
+	k = (ix&0x7f800000)>>23;           /* extract exponent */
+	if (k == 0) {                      /* 0 or subnormal x */
+		if ((ix&0x7fffffff) == 0)  /* +-0 */
+			return x;
+		x *= two25;
+		GET_FLOAT_WORD(ix, x);
+		k = ((ix&0x7f800000)>>23) - 25;
+		if (n < -50000)
+			return tiny*x;  /*underflow*/
+	}
+	if (k == 0xff)                     /* NaN or Inf */
+		return x + x;
+	k = k + n;
+	if (k > 0xfe)
+		return huge*copysignf(huge, x);  /* overflow  */
+	if (k > 0) {                       /* normal result */
+		SET_FLOAT_WORD(x, (ix&0x807fffff)|(k<<23));
+		return x;
+	}
+	if (k <= -25)
+		if (n > 50000)  /* in case integer overflow in n+k */
+			return huge*copysignf(huge,x);  /*overflow*/
+		return tiny*copysignf(tiny, x);  /*underflow*/
+	k += 25;                           /* subnormal result */
+	SET_FLOAT_WORD(x, (ix&0x807fffff)|(k<<23));
+	return x*twom25;
+}