1 files changed, 75 insertions, 0 deletions
diff --git a/src/math/acosf.c b/src/math/acosf.c
new file mode 100644
index 00000000..dd3bba29
--- /dev/null
+++ b/src/math/acosf.c
@@ -0,0 +1,75 @@
+/* origin: FreeBSD /usr/src/lib/msun/src/e_acosf.c */
+/*
+ * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
+ */
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+#include "libm.h"
+
+static const float
+one = 1.0000000000e+00, /* 0x3F800000 */
+pi  = 3.1415925026e+00, /* 0x40490fda */
+pio2_hi = 1.5707962513e+00; /* 0x3fc90fda */
+static volatile float
+pio2_lo = 7.5497894159e-08; /* 0x33a22168 */
+static const float
+pS0 =  1.6666586697e-01,
+pS1 = -4.2743422091e-02,
+pS2 = -8.6563630030e-03,
+qS1 = -7.0662963390e-01;
+
+float acosf(float x)
+{
+	float z,p,q,r,w,s,c,df;
+	int32_t hx,ix;
+
+	GET_FLOAT_WORD(hx, x);
+	ix = hx & 0x7fffffff;
+	if (ix >= 0x3f800000) {  /* |x| >= 1 */
+		if (ix == 0x3f800000) {  /* |x| == 1 */
+			if(hx>0) return 0.0;  /* acos(1) = 0 */
+			return pi + (float)2.0*pio2_lo;  /* acos(-1)= pi */
+		}
+		return (x-x)/(x-x);  /* acos(|x|>1) is NaN */
+	}
+	if (ix < 0x3f000000) {   /* |x| < 0.5 */
+		if (ix <= 0x32800000) /* |x| < 2**-26 */
+			return pio2_hi + pio2_lo;
+		z = x*x;
+		p = z*(pS0+z*(pS1+z*pS2));
+		q = one+z*qS1;
+		r = p/q;
+		return pio2_hi - (x - (pio2_lo-x*r));
+	} else if (hx < 0) {     /* x < -0.5 */
+		z = (one+x)*(float)0.5;
+		p = z*(pS0+z*(pS1+z*pS2));
+		q = one+z*qS1;
+		s = sqrtf(z);
+		r = p/q;
+		w = r*s-pio2_lo;
+		return pi - (float)2.0*(s+w);
+	} else {                 /* x > 0.5 */
+		int32_t idf;
+
+		z = (one-x)*(float)0.5;
+		s = sqrtf(z);
+		df = s;
+		GET_FLOAT_WORD(idf,df);
+		SET_FLOAT_WORD(df,idf&0xfffff000);
+		c  = (z-df*df)/(s+df);
+		p = z*(pS0+z*(pS1+z*pS2));
+		q = one+z*qS1;
+		r = p/q;
+		w = r*s+c;
+		return (float)2.0*(df+w);
+	}
+}