Add a copy of FreeBSD's lib/libc/aarch64/_fpmath.h.

This makes it possible to build OpenLibm on ARM64 CPUs.

Author: EdSchouten

src/aarch64_fpmath.h

@@ -0,0 +1,58 @@
+/*-
+ * Copyright (c) 2002, 2003 David Schultz <das@FreeBSD.ORG>
+ * Copyright (2) 2014 The FreeBSD Foundation
+ * 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: head/lib/libc/aarch64/_fpmath.h 281197 2015-04-07 09:52:14Z andrew $
+ */
+
+union IEEEl2bits {
+	long double	e;
+	struct {
+		unsigned long	manl	:64;
+		unsigned long	manh	:48;
+		unsigned int	exp	:15;
+		unsigned int	sign	:1;
+	} bits;
+	/* TODO andrew: Check the packing here */
+	struct {
+		unsigned long	manl	:64;
+		unsigned long	manh	:48;
+		unsigned int	expsign	:16;
+	} xbits;
+};
+
+#define	LDBL_NBIT	0
+#define	LDBL_IMPLICIT_NBIT
+#define	mask_nbit_l(u)	((void)0)
+
+#define	LDBL_MANH_SIZE	48
+#define	LDBL_MANL_SIZE	64
+
+#define	LDBL_TO_ARRAY32(u, a) do {			\
+	(a)[0] = (uint32_t)(u).bits.manl;		\
+	(a)[1] = (uint32_t)((u).bits.manl >> 32);	\
+	(a)[2] = (uint32_t)(u).bits.manh;		\
+	(a)[3] = (uint32_t)((u).bits.manh >> 32);	\
+} while(0)

src/fpmath.h

@@ -29,8 +29,9 @@
 #ifndef _FPMATH_H_
 #define _FPMATH_H_
 
-// Currently assumes Intel platform
-#if defined (__i386__) || defined(__x86_64__)
+#if defined(__aarch64__)
+#include "aarch64_fpmath.h"
+#elif defined(__i386__) || defined(__x86_64__)
 #ifdef __LP64__
 #include "amd64_fpmath.h"
 #else