first commit of the new libm!

[musl] / src / math / nextafterl.c

diff --git a/src/math/nextafterl.c b/src/math/nextafterl.c
new file mode 100644 (file)
index 0000000..aec8ab4
--- /dev/null
+++ b/src/math/nextafterl.c
@@ -0,0 +1,77 @@
+/* origin: FreeBSD /usr/src/lib/msun/src/s_nextafterl.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.
+ * ====================================================
+ */
+/* IEEE functions
+ *      nextafter(x,y)
+ *      return the next machine floating-point number of x in the
+ *      direction toward y.
+ *   Special cases:
+ */
+
+#include "libm.h"
+
+#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
+long double nextafterl(long double x, long double y)
+{
+       return nextafter(x, y);
+}
+#elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
+long double nextafterl(long double x, long double y)
+{
+       volatile long double t;
+       union IEEEl2bits ux, uy;
+
+       ux.e = x;
+       uy.e = y;
+
+       if ((ux.bits.exp == 0x7fff && ((ux.bits.manh&~LDBL_NBIT)|ux.bits.manl) != 0) ||
+           (uy.bits.exp == 0x7fff && ((uy.bits.manh&~LDBL_NBIT)|uy.bits.manl) != 0))
+               return x+y;  /* x or y is nan */
+       if (x == y)
+               return y;    /* x=y, return y */
+       if (x == 0.0) {
+               /* return +-minsubnormal */
+               ux.bits.manh = 0;
+               ux.bits.manl = 1;
+               ux.bits.sign = uy.bits.sign;
+               /* raise underflow flag */
+               t = ux.e*ux.e;
+               if (t == ux.e)
+                       return t;
+               return ux.e;
+       }
+       if(x > 0.0 ^ x < y) {  /* x -= ulp */
+               if (ux.bits.manl == 0) {
+                       if ((ux.bits.manh&~LDBL_NBIT) == 0)
+                               ux.bits.exp--;
+                       ux.bits.manh = (ux.bits.manh - 1) | (ux.bits.manh & LDBL_NBIT);
+               }
+               ux.bits.manl--;
+       } else {               /* x += ulp */
+               ux.bits.manl++;
+               if (ux.bits.manl == 0) {
+                       ux.bits.manh = (ux.bits.manh + 1) | (ux.bits.manh & LDBL_NBIT);
+                       if ((ux.bits.manh&~LDBL_NBIT)==0)
+                               ux.bits.exp++;
+               }
+       }
+       if (ux.bits.exp == 0x7fff)  /* overflow  */
+               return x+x;
+       if (ux.bits.exp == 0) {     /* underflow */
+               mask_nbit_l(ux);
+               /* raise underflow flag */
+               t = ux.e * ux.e;
+               if (t != ux.e)
+                       return ux.e;
+       }
+       return ux.e;
+}
+#endif