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

fusl/src/complex/__cexpf.c

+/* origin: FreeBSD /usr/src/lib/msun/src/k_expf.c */
+/*-
+ * Copyright (c) 2011 David Schultz <das@FreeBSD.ORG>
+ * 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, 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 AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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.
+ */
+
+#include "libm.h"
+
+static const uint32_t k = 235; /* constant for reduction */
+static const float kln2 = 162.88958740F; /* k * ln2 */
+
+/*
+ * See __cexp.c for details.
+ *
+ * Input:  ln(FLT_MAX) <= x < ln(2 * FLT_MAX / FLT_MIN_DENORM) ~= 192.7
+ * Output: 2**127 <= y < 2**128
+ */
+static float __frexp_expf(float x, int *expt)
+{
+        float exp_x;
+        uint32_t hx;
+
+        exp_x = expf(x - kln2);
+        GET_FLOAT_WORD(hx, exp_x);
+        *expt = (hx >> 23) - (0x7f + 127) + k;
+        SET_FLOAT_WORD(exp_x, (hx & 0x7fffff) | ((0x7f + 127) << 23));
+        return exp_x;
+}
+
+float complex __ldexp_cexpf(float complex z, int expt)
+{
+        float x, y, exp_x, scale1, scale2;
+        int ex_expt, half_expt;
+
+        x = crealf(z);
+        y = cimagf(z);
+        exp_x = __frexp_expf(x, &ex_expt);
+        expt += ex_expt;
+
+        half_expt = expt / 2;
+        SET_FLOAT_WORD(scale1, (0x7f + half_expt) << 23);
+        half_expt = expt - half_expt;
+        SET_FLOAT_WORD(scale2, (0x7f + half_expt) << 23);
+
+        return CMPLXF(cosf(y) * exp_x * scale1 * scale2,
+          sinf(y) * exp_x * scale1 * scale2);
+}