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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/e_remainder.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/e_remainder.c')
-rw-r--r--libm/e_remainder.c80
1 files changed, 80 insertions, 0 deletions
diff --git a/libm/e_remainder.c b/libm/e_remainder.c
new file mode 100644
index 000000000..641808118
--- /dev/null
+++ b/libm/e_remainder.c
@@ -0,0 +1,80 @@
+/* @(#)e_remainder.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: e_remainder.c,v 1.8 1995/05/10 20:46:05 jtc Exp $";
+#endif
+
+/* __ieee754_remainder(x,p)
+ * Return :
+ * returns x REM p = x - [x/p]*p as if in infinite
+ * precise arithmetic, where [x/p] is the (infinite bit)
+ * integer nearest x/p (in half way case choose the even one).
+ * Method :
+ * Based on fmod() return x-[x/p]chopped*p exactlp.
+ */
+
+#include "math.h"
+#include "math_private.h"
+
+#ifdef __STDC__
+static const double zero = 0.0;
+#else
+static double zero = 0.0;
+#endif
+
+
+#ifdef __STDC__
+ double __ieee754_remainder(double x, double p)
+#else
+ double __ieee754_remainder(x,p)
+ double x,p;
+#endif
+{
+ int32_t hx,hp;
+ u_int32_t sx,lx,lp;
+ double p_half;
+
+ EXTRACT_WORDS(hx,lx,x);
+ EXTRACT_WORDS(hp,lp,p);
+ sx = hx&0x80000000;
+ hp &= 0x7fffffff;
+ hx &= 0x7fffffff;
+
+ /* purge off exception values */
+ if((hp|lp)==0) return (x*p)/(x*p); /* p = 0 */
+ if((hx>=0x7ff00000)|| /* x not finite */
+ ((hp>=0x7ff00000)&& /* p is NaN */
+ (((hp-0x7ff00000)|lp)!=0)))
+ return (x*p)/(x*p);
+
+
+ if (hp<=0x7fdfffff) x = __ieee754_fmod(x,p+p); /* now x < 2p */
+ if (((hx-hp)|(lx-lp))==0) return zero*x;
+ x = fabs(x);
+ p = fabs(p);
+ if (hp<0x00200000) {
+ if(x+x>p) {
+ x-=p;
+ if(x+x>=p) x -= p;
+ }
+ } else {
+ p_half = 0.5*p;
+ if(x>p_half) {
+ x-=p;
+ if(x>=p_half) x -= p;
+ }
+ }
+ GET_HIGH_WORD(hx,x);
+ SET_HIGH_WORD(x,hx^sx);
+ return x;
+}