1 files changed, 59 insertions, 0 deletions
diff --git a/lib/libc/gen/frexp.c b/lib/libc/gen/frexp.c
new file mode 100644
index 0000000000000..e65332a0bddee
--- /dev/null
+++ b/lib/libc/gen/frexp.c
@@ -0,0 +1,59 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2004 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.
+ *
+ * $FreeBSD$
+ */
+
+#include <math.h>
+
+#include "fpmath.h"
+
+double
+frexp(double d, int *ex)
+{
+	union IEEEd2bits u;
+
+	u.d = d;
+	switch (u.bits.exp) {
+	case 0:		/* 0 or subnormal */
+		if ((u.bits.manl | u.bits.manh) == 0) {
+			*ex = 0;
+		} else {
+			u.d *= 0x1.0p514;
+			*ex = u.bits.exp - 1536;
+			u.bits.exp = 1022;
+		}
+		break;
+	case 2047:	/* infinity or NaN; value of *ex is unspecified */
+		break;
+	default:	/* normal */
+		*ex = u.bits.exp - 1022;
+		u.bits.exp = 1022;
+		break;
+	}
+	return (u.d);
+}