-/* origin: FreeBSD /usr/src/lib/msun/src/s_round.c */
-/*-
- * Copyright (c) 2003, Steven G. Kargl
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- * notice unmodified, this list of conditions, and the following
- * disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
- * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
- * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
- * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
- * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
+#include "libm.h"
-#include <math.h>
+#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 round(double x)
{
- double t;
+ union {double f; uint64_t i;} u = {x};
+ int e = u.i >> 52 & 0x7ff;
+ double_t y;
- if (!isfinite(x))
+ if (e >= 0x3ff+52)
return x;
-
- if (x >= 0.0) {
- t = floor(x);
- if (t - x <= -0.5)
- t += 1.0;
- return t;
- } else {
- t = floor(-x);
- if (t + x <= -0.5)
- t += 1.0;
- return -t;
+ if (u.i >> 63)
+ x = -x;
+ if (e < 0x3ff-1) {
+ /* raise inexact if x!=0 */
+ FORCE_EVAL(x + toint);
+ return 0*u.f;
}
+ y = x + toint - toint - x;
+ if (y > 0.5)
+ y = y + x - 1;
+ else if (y <= -0.5)
+ y = y + x + 1;
+ else
+ y = y + x;
+ if (u.i >> 63)
+ y = -y;
+ return y;
}