From 4abab5ad6c8465a7528ccdd5f49367da05f78bbd Mon Sep 17 00:00:00 2001
From: Vladimir Azarov <avm@intermediate-node.net>
Date: Tue, 1 Oct 2024 15:47:05 +0200
Subject: Initial version

---
 src/math/i386/acos.s | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 src/math/i386/acos.s

(limited to 'src/math/i386/acos.s')

diff --git a/src/math/i386/acos.s b/src/math/i386/acos.s
new file mode 100644
index 0000000..af423a2
--- /dev/null
+++ b/src/math/i386/acos.s
@@ -0,0 +1,18 @@
+# use acos(x) = atan2(fabs(sqrt((1-x)*(1+x))), x)
+
+.global acos
+.type acos,@function
+acos:
+	fldl 4(%esp)
+	fld %st(0)
+	fld1
+	fsub %st(0),%st(1)
+	fadd %st(2)
+	fmulp
+	fsqrt
+	fabs         # fix sign of zero (matters in downward rounding mode)
+	fxch %st(1)
+	fpatan
+	fstpl 4(%esp)
+	fldl 4(%esp)
+	ret
-- 
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