From ea9bb95a5b36c0a3d2ed8fb03808745b406c2633 Mon Sep 17 00:00:00 2001
From: Szabolcs Nagy <nsz@port70.net>
Date: Tue, 3 Sep 2013 18:50:58 +0000
Subject: math: long double trigonometric cleanup (cosl, sinl, sincosl, tanl)

ld128 support was added to internal kernel functions (__cosl, __sinl,
__tanl, __rem_pio2l) from freebsd (not tested, but should be a good
start for when ld128 arch arrives)

__rem_pio2l had some code cleanup, the freebsd ld128 code seems to
gather the results of a large reduction with precision loss (fixed
the bug but a todo comment was added for later investigation)

the old copyright was removed from the non-kernel wrapper functions
(cosl, sinl, sincosl, tanl) since these are trivial and the interesting
parts and comments had been already rewritten.
---
 src/math/tanl.c | 53 +++++++----------------------------------------------
 1 file changed, 7 insertions(+), 46 deletions(-)

(limited to 'src/math/tanl.c')

diff --git a/src/math/tanl.c b/src/math/tanl.c
index 546c7a02..6af06712 100644
--- a/src/math/tanl.c
+++ b/src/math/tanl.c
@@ -1,35 +1,3 @@
-/* origin: FreeBSD /usr/src/lib/msun/src/s_tanl.c */
-/*-
- * Copyright (c) 2007 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.
- */
-/*
- * Limited testing on pseudorandom numbers drawn within [0:4e8] shows
- * an accuracy of <= 1.5 ULP where 247024 values of x out of 40 million
- * possibles resulted in tan(x) that exceeded 0.5 ULP (ie., 0.6%).
- */
-
 #include "libm.h"
 
 #if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
@@ -40,28 +8,21 @@ long double tanl(long double x)
 #elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
 long double tanl(long double x)
 {
-	union IEEEl2bits z;
+	union ldshape u = {x};
 	long double y[2];
 	unsigned n;
 
-	z.e = x;
-	z.bits.sign = 0;
-
-	/* If x = NaN or Inf, then tan(x) = NaN. */
-	if (z.bits.exp == 0x7fff)
-		return (x - x) / (x - x);
-
-	/* |x| < (double)pi/4 */
-	if (z.e < M_PI_4) {
-		/* |x| < 0x1p-64 */
-		if (z.bits.exp < 0x3fff - 64) {
+	u.i.se &= 0x7fff;
+	if (u.i.se == 0x7fff)
+		return x - x;
+	if (u.f < M_PI_4) {
+		if (u.i.se < 0x3fff - LDBL_MANT_DIG/2) {
 			/* raise inexact if x!=0 and underflow if subnormal */
-			FORCE_EVAL(z.bits.exp == 0 ? x/0x1p120f : x+0x1p120f);
+			FORCE_EVAL(u.i.se == 0 ? x*0x1p-120f : x+0x1p120f);
 			return x;
 		}
 		return __tanl(x, 0, 0);
 	}
-
 	n = __rem_pio2l(x, y);
 	return __tanl(y[0], y[1], n&1);
 }
-- 
cgit v1.2.1