first commit of the new libm!

[musl] / src / math / modfl.c

diff --git a/src/math/modfl.c b/src/math/modfl.c
new file mode 100644 (file)
index 0000000..2ca67b1
--- /dev/null
+++ b/src/math/modfl.c
@@ -0,0 +1,100 @@
+/* origin: FreeBSD /usr/src/lib/msun/src/s_modfl.c */
+/*-
+ * Copyright (c) 2007 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.
+ *
+ * Derived from s_modf.c, which has the following Copyright:
+ * ====================================================
+ * 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"
+
+#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
+long double modfl(long double x, long double *iptr)
+{
+       return modf(x, iptr);
+}
+#elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
+
+#if LDBL_MANL_SIZE > 32
+#define MASK    ((uint64_t)-1)
+#else
+#define MASK    ((uint32_t)-1)
+#endif
+/* Return the last n bits of a word, representing the fractional part. */
+#define GETFRAC(bits, n)        ((bits) & ~(MASK << (n)))
+/* The number of fraction bits in manh, not counting the integer bit */
+#define HIBITS  (LDBL_MANT_DIG - LDBL_MANL_SIZE)
+
+static const long double zero[] = { 0.0L, -0.0L };
+
+long double modfl(long double x, long double *iptr)
+{
+       union IEEEl2bits ux;
+       int e;
+
+       ux.e = x;
+       e = ux.bits.exp - LDBL_MAX_EXP + 1;
+       if (e < HIBITS) {                       /* Integer part is in manh. */
+               if (e < 0) {                    /* |x|<1 */
+                       *iptr = zero[ux.bits.sign];
+                       return x;
+               }
+               if ((GETFRAC(ux.bits.manh, HIBITS - 1 - e)|ux.bits.manl) == 0) {
+                       /* x is an integer. */
+                       *iptr = x;
+                       return zero[ux.bits.sign];
+               }
+               /* Clear all but the top e+1 bits. */
+               ux.bits.manh >>= HIBITS - 1 - e;
+               ux.bits.manh <<= HIBITS - 1 - e;
+               ux.bits.manl = 0;
+               *iptr = ux.e;
+               return x - ux.e;
+       } else if (e >= LDBL_MANT_DIG - 1) {    /* x has no fraction part. */
+               *iptr = x;
+               if (x != x)                     /* Handle NaNs. */
+                       return x;
+               return zero[ux.bits.sign];
+       } else {                                /* Fraction part is in manl. */
+               if (GETFRAC(ux.bits.manl, LDBL_MANT_DIG - 1 - e) == 0) {
+                       /* x is integral. */
+                       *iptr = x;
+                       return zero[ux.bits.sign];
+               }
+               /* Clear all but the top e+1 bits. */
+               ux.bits.manl >>= LDBL_MANT_DIG - 1 - e;
+               ux.bits.manl <<= LDBL_MANT_DIG - 1 - e;
+               *iptr = ux.e;
+               return x - ux.e;
+       }
+}
+#endif