math: nextafter and nexttoward cleanup

[musl] / src / math / nexttowardf.c

diff --git a/src/math/nexttowardf.c b/src/math/nexttowardf.c
index c52ef3a..821f72a 100644 (file)
--- a/src/math/nexttowardf.c
+++ b/src/math/nexttowardf.c
@@ -1,62 +1,37 @@
-/* origin: FreeBSD /usr/src/lib/msun/src/s_nexttowardf.c */
-/*
- * ====================================================
- * 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"
 
-#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
-// FIXME
-#elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
-#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;
+       union fshape ux;
+       uint32_t e;
 
-       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 (isnan(x) || isnan(y))
+               return x + y;
        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 */
-               /* raise underflow flag */
-               t = x*x;
-               if (t == x)
-                       return t;
-               return x;
+               return y;
+       ux.value = x;
+       if (x == 0) {
+               ux.bits = 1;
+               if (signbit(y))
+                       ux.bits |= 0x80000000;
+       } else if (x < y) {
+               if (signbit(x))
+                       ux.bits--;
+               else
+                       ux.bits++;
+       } else {
+               if (signbit(x))
+                       ux.bits++;
+               else
+                       ux.bits--;
        }
-       if (hx >= 0 ^ x < y)  /* x -= ulp */
-               hx--;
-       else                  /* x += ulp */
-               hx++;
-       ix = hx & 0x7f800000;
-       if (ix >= 0x7f800000)  /* overflow  */
-               return x+x;
-       if (ix < 0x00800000) { /* underflow */
-               /* raise underflow flag */
-               t = x*x;
-               if (t != x) {
-                       SET_FLOAT_WORD(x, hx);
-                       return x;
-               }
+       e = ux.bits & 0x7f800000;
+       /* raise overflow if ux.value is infinite and x is finite */
+       if (e == 0x7f800000)
+               return x + x;
+       /* raise underflow if ux.value is subnormal or zero */
+       if (e == 0) {
+               volatile float z = x*x + ux.value*ux.value;
        }
-       SET_FLOAT_WORD(x, hx);
-       return x;
+       return ux.value;
 }
-#endif