From: nsz <nsz@port70.net>
Date: Wed, 4 Apr 2012 15:34:28 +0000 (+0200)
Subject: math: fix x86 asin accuracy
X-Git-Tag: v0.8.8~41^2
X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=37eaec3ad396ea4502f4aea2395b3b5f5f69a1c6;p=oweals%2Fmusl.git

math: fix x86 asin accuracy
use (1-x)*(1+x) instead of (1-x*x) in asin.s
the later can be inaccurate with upward rounding when x is close to 1
---

diff --git a/src/math/i386/asin.s b/src/math/i386/asin.s
index cab7bfc8..932c7542 100644
--- a/src/math/i386/asin.s
+++ b/src/math/i386/asin.s
@@ -15,9 +15,10 @@ asinl:
 asin:
 	fldl 4(%esp)
 1:	fld %st(0)
-	fmul %st(0)
 	fld1
-	fsubp %st(1)
+	fsub %st(0),%st(1)
+	fadd %st(2)
+	fmulp
 	fsqrt
 	fpatan
 	ret
diff --git a/src/math/x86_64/asinl.s b/src/math/x86_64/asinl.s
index 83c392f7..ed212d9a 100644
--- a/src/math/x86_64/asinl.s
+++ b/src/math/x86_64/asinl.s
@@ -3,10 +3,10 @@
 asinl:
 	fldt 8(%rsp)
 1:	fld %st(0)
-	fmul %st(0)
 	fld1
-	fsubp %st(1)
+	fsub %st(0),%st(1)
+	fadd %st(2)
+	fmulp
 	fsqrt
 	fpatan
 	ret
-