Add a "fork" of musl as //fusl.

fusl/src/math/cosf.c

Index: fusl/src/math/cosf.c
diff --git a/fusl/src/math/cosf.c b/fusl/src/math/cosf.c
new file mode 100644
index 0000000000000000000000000000000000000000..23f3e5bf69f29e3177035c0368f8778e2fc50ce1
--- /dev/null
+++ b/fusl/src/math/cosf.c
@@ -0,0 +1,78 @@
+/* origin: FreeBSD /usr/src/lib/msun/src/s_cosf.c */
+/*
+ * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
+ * Optimized by Bruce D. Evans.
+ */
+/*
+ * ====================================================
+ * 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"
+
+/* Small multiples of pi/2 rounded to double precision. */
+static const double
+c1pio2 = 1*M_PI_2, /* 0x3FF921FB, 0x54442D18 */
+c2pio2 = 2*M_PI_2, /* 0x400921FB, 0x54442D18 */
+c3pio2 = 3*M_PI_2, /* 0x4012D97C, 0x7F3321D2 */
+c4pio2 = 4*M_PI_2; /* 0x401921FB, 0x54442D18 */
+
+float cosf(float x)
+{
+	double y;
+	uint32_t ix;
+	unsigned n, sign;
+
+	GET_FLOAT_WORD(ix, x);
+	sign = ix >> 31;
+	ix &= 0x7fffffff;
+
+	if (ix <= 0x3f490fda) {  /* |x| ~<= pi/4 */
+		if (ix < 0x39800000) {  /* |x| < 2**-12 */
+			/* raise inexact if x != 0 */
+			FORCE_EVAL(x + 0x1p120f);
+			return 1.0f;
+		}
+		return __cosdf(x);
+	}
+	if (ix <= 0x407b53d1) {  /* |x| ~<= 5*pi/4 */
+		if (ix > 0x4016cbe3)  /* |x|  ~> 3*pi/4 */
+			return -__cosdf(sign ? x+c2pio2 : x-c2pio2);
+		else {
+			if (sign)
+				return __sindf(x + c1pio2);
+			else
+				return __sindf(c1pio2 - x);
+		}
+	}
+	if (ix <= 0x40e231d5) {  /* |x| ~<= 9*pi/4 */
+		if (ix > 0x40afeddf)  /* |x| ~> 7*pi/4 */
+			return __cosdf(sign ? x+c4pio2 : x-c4pio2);
+		else {
+			if (sign)
+				return __sindf(-x - c3pio2);
+			else
+				return __sindf(x - c3pio2);
+		}
+	}
+
+	/* cos(Inf or NaN) is NaN */
+	if (ix >= 0x7f800000)
+		return x-x;
+
+	/* general argument reduction needed */
+	n = __rem_pio2f(x,&y);
+	switch (n&3) {
+	case 0: return  __cosdf(y);
+	case 1: return  __sindf(-y);
+	case 2: return -__cosdf(y);
+	default:
+		return  __sindf(y);
+	}
+}