first commit of the new libm!

[musl] / src / math / lround.c

diff --git a/src/math/lround.c b/src/math/lround.c
new file mode 100644 (file)
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--- /dev/null
+++ b/src/math/lround.c
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+/* origin: FreeBSD /usr/src/lib/msun/src/s_lround.c */
+/*-
+ * Copyright (c) 2005 David Schultz <das@FreeBSD.ORG>
+ * 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, 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 AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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 <limits.h>
+#include <fenv.h>
+#include "libm.h"
+
+#ifndef type
+#define type            double
+#define roundit         round
+#define dtype           long
+#define DTYPE_MIN       LONG_MIN
+#define DTYPE_MAX       LONG_MAX
+#define fn              lround
+#endif
+
+/*
+ * If type has more precision than dtype, the endpoints dtype_(min|max) are
+ * of the form xxx.5; they are "out of range" because lround() rounds away
+ * from 0.  On the other hand, if type has less precision than dtype, then
+ * all values that are out of range are integral, so we might as well assume
+ * that everything is in range.  At compile time, INRANGE(x) should reduce to
+ * two floating-point comparisons in the former case, or TRUE otherwise.
+ */
+static const type dtype_min = DTYPE_MIN - 0.5;
+static const type dtype_max = DTYPE_MAX + 0.5;
+#define INRANGE(x) \
+ (dtype_max - DTYPE_MAX != 0.5 || ((x) > dtype_min && (x) < dtype_max))
+
+dtype fn(type x)
+{
+
+       if (INRANGE(x)) {
+               x = roundit(x);
+               return (dtype)x;
+       } else {
+               feraiseexcept(FE_INVALID);
+               return DTYPE_MAX;
+       }
+}