math: fix expm1f overflow threshold

[musl] / src / math / ceil.c

diff --git a/src/math/ceil.c b/src/math/ceil.c
index c2ab4a5..b13e6f2 100644 (file)
--- a/src/math/ceil.c
+++ b/src/math/ceil.c
@@ -1,83 +1,31 @@
-/* origin: FreeBSD /usr/src/lib/msun/src/s_ceil.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.
- * ====================================================
- */
-/*
- * ceil(x)
- * Return x rounded toward -inf to integral value
- * Method:
- *      Bit twiddling.
- * Exception:
- *      Inexact flag raised if x not equal to ceil(x).
- */
-
 #include "libm.h"
 
-static const double huge = 1.0e300;
+#if FLT_EVAL_METHOD==0 || FLT_EVAL_METHOD==1
+#define EPS DBL_EPSILON
+#elif FLT_EVAL_METHOD==2
+#define EPS LDBL_EPSILON
+#endif
+static const double_t toint = 1/EPS;
 
 double ceil(double x)
 {
-       int32_t i0,i1,j0;
-       uint32_t i,j;
+       union {double f; uint64_t i;} u = {x};
+       int e = u.i >> 52 & 0x7ff;
+       double_t y;
 
-       EXTRACT_WORDS(i0, i1, x);
-       // FIXME signed shift
-       j0 = ((i0>>20)&0x7ff) - 0x3ff;
-       if (j0 < 20) {
-               if (j0 < 0) {
-                        /* raise inexact if x != 0 */
-                       if (huge+x > 0.0) {
-                               /* return 0*sign(x) if |x|<1 */
-                               if (i0 < 0) {
-                                       i0 = 0x80000000;
-                                       i1=0;
-                               } else if ((i0|i1) != 0) {
-                                       i0=0x3ff00000;
-                                       i1=0;
-                               }
-                       }
-               } else {
-                       i = (0x000fffff)>>j0;
-                       if (((i0&i)|i1) == 0) /* x is integral */
-                               return x;
-                       /* raise inexact flag */
-                       if (huge+x > 0.0) {
-                               if (i0 > 0)
-                                       i0 += 0x00100000>>j0;
-                               i0 &= ~i;
-                               i1 = 0;
-                       }
-               }
-       } else if (j0 > 51) {
-               if (j0 == 0x400)  /* inf or NaN */
-                       return x+x;
-               return x;         /* x is integral */
-       } else {
-               i = (uint32_t)0xffffffff>>(j0-20);
-               if ((i1&i) == 0)
-                       return x; /* x is integral */
-               /* raise inexact flag */
-               if (huge+x > 0.0) {
-                       if (i0 > 0) {
-                               if (j0 == 20)
-                                       i0 += 1;
-                               else {
-                                       j = i1 + (1<<(52-j0));
-                                       if (j < i1)  /* got a carry */
-                                               i0 += 1;
-                                       i1 = j;
-                               }
-                       }
-                       i1 &= ~i;
-               }
+       if (e >= 0x3ff+52 || x == 0)
+               return x;
+       /* y = int(x) - x, where int(x) is an integer neighbor of x */
+       if (u.i >> 63)
+               y = x - toint + toint - x;
+       else
+               y = x + toint - toint - x;
+       /* special case because of non-nearest rounding modes */
+       if (e <= 0x3ff-1) {
+               FORCE_EVAL(y);
+               return u.i >> 63 ? -0.0 : 1;
        }
-       INSERT_WORDS(x, i0, i1);
-       return x;
+       if (y < 0)
+               return x + y + 1;
+       return x + y;
 }