Implement nexttowardf. This is used on both platforms with 11-bit

exponents and platforms with 15-bit exponents for long doubles.

lib/msun/src/s_nexttowardf.c

@@ -0,0 +1,60 @@
+/*
+ * ====================================================
+ * 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.
+ * ====================================================
+ */
+
+#ifndef lint
+static char rcsid[] = "$FreeBSD$";
+#endif
+
+#include <float.h>
+
+#include "fpmath.h"
+#include "math.h"
+#include "math_private.h"
+
+#define	LDBL_INFNAN_EXP	(LDBL_MAX_EXP * 2 - 1)
+
+float
+nexttowardf(float x, long double y)
+{
+	union IEEEl2bits uy;
+	volatile float t;
+	int32_t hx,ix;
+
+	GET_FLOAT_WORD(hx,x);
+	ix = hx&0x7fffffff;		/* |x| */
+	uy.e = y;
+
+	if((ix>0x7f800000) ||
+	   (uy.bits.exp == LDBL_INFNAN_EXP &&
+	    ((uy.bits.manh&~LDBL_NBIT)|uy.bits.manl) != 0))
+	   return x+y;	/* x or y is nan */
+	if(x==y) return (float)y;		/* x=y, return y */
+	if(ix==0) {				/* x == 0 */
+	    SET_FLOAT_WORD(x,(uy.bits.sign<<31)|1);/* return +-minsubnormal */
+	    t = x*x;
+	    if(t==x) return t; else return x;	/* raise underflow flag */
+	}
+	if(hx>=0 ^ x < y)			/* x -= ulp */
+	    hx -= 1;
+	else					/* x += ulp */
+	    hx += 1;
+	ix = hx&0x7f800000;
+	if(ix>=0x7f800000) return x+x;	/* overflow  */
+	if(ix<0x00800000) {		/* underflow */
+	    t = x*x;
+	    if(t!=x) {		/* raise underflow flag */
+	        SET_FLOAT_WORD(y,hx);
+		return y;
+	    }
+	}
+	SET_FLOAT_WORD(x,hx);
+	return x;
+}