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authorEric Andersen <andersen@codepoet.org>2001-11-22 14:04:29 +0000
committerEric Andersen <andersen@codepoet.org>2001-11-22 14:04:29 +0000
commit7ce331c01ce6eb7b3f5c715a38a24359da9c6ee2 (patch)
tree3a7e8476e868ae15f4da1b7ce26b2db6f434468c /libm/s_frexp.c
parentc117dd5fb183afb1a4790a6f6110d88704be6bf8 (diff)
Totally rework the math library, this time based on the MacOs X
math library (which is itself based on the math lib from FreeBSD). -Erik
Diffstat (limited to 'libm/s_frexp.c')
-rw-r--r--libm/s_frexp.c61
1 files changed, 61 insertions, 0 deletions
diff --git a/libm/s_frexp.c b/libm/s_frexp.c
new file mode 100644
index 000000000..f187d8472
--- /dev/null
+++ b/libm/s_frexp.c
@@ -0,0 +1,61 @@
+#if !defined(__ppc__)
+/* @(#)s_frexp.c 5.1 93/09/24 */
+/*
+ * ====================================================
+ * 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.
+ * ====================================================
+ */
+
+#if defined(LIBM_SCCS) && !defined(lint)
+static char rcsid[] = "$NetBSD: s_frexp.c,v 1.9 1995/05/10 20:47:24 jtc Exp $";
+#endif
+
+/*
+ * for non-zero x
+ * x = frexp(arg,&exp);
+ * return a double fp quantity x such that 0.5 <= |x| <1.0
+ * and the corresponding binary exponent "exp". That is
+ * arg = x*2^exp.
+ * If arg is inf, 0.0, or NaN, then frexp(arg,&exp) returns arg
+ * with *exp=0.
+ */
+
+#include "math.h"
+#include "math_private.h"
+
+#ifdef __STDC__
+static const double
+#else
+static double
+#endif
+two54 = 1.80143985094819840000e+16; /* 0x43500000, 0x00000000 */
+
+#ifdef __STDC__
+ double frexp(double x, int *eptr)
+#else
+ double frexp(x, eptr)
+ double x; int *eptr;
+#endif
+{
+ int32_t hx, ix, lx;
+ EXTRACT_WORDS(hx,lx,x);
+ ix = 0x7fffffff&hx;
+ *eptr = 0;
+ if(ix>=0x7ff00000||((ix|lx)==0)) return x; /* 0,inf,nan */
+ if (ix<0x00100000) { /* subnormal */
+ x *= two54;
+ GET_HIGH_WORD(hx,x);
+ ix = hx&0x7fffffff;
+ *eptr = -54;
+ }
+ *eptr += (ix>>20)-1022;
+ hx = (hx&0x800fffff)|0x3fe00000;
+ SET_HIGH_WORD(x,hx);
+ return x;
+}
+#endif /* !__ppc__ */