atan2 for long double.

1 files changed, 136 insertions, 0 deletions

diff --git a/sysdeps/libm-ieee754/e_atan2l.c b/sysdeps/libm-ieee754/e_atan2l.c
new file mode 100644
index 0000000000..72d3eac172
--- /dev/null
+++ b/sysdeps/libm-ieee754/e_atan2l.c
@@ -0,0 +1,136 @@
+/* e_atan2l.c -- long double version of e_atan2.c.
+ * Conversion to long double by Ulrich Drepper,
+ * Cygnus Support, drepper@cygnus.com.
+ */
+
+/*
+ * ====================================================
+ * 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: $";
+#endif
+
+/* __ieee754_atan2l(y,x)
+ * Method :
+ *	1. Reduce y to positive by atan2(y,x)=-atan2(-y,x).
+ *	2. Reduce x to positive by (if x and y are unexceptional):
+ *		ARG (x+iy) = arctan(y/x)   	   ... if x > 0,
+ *		ARG (x+iy) = pi - arctan[y/(-x)]   ... if x < 0,
+ *
+ * Special cases:
+ *
+ *	ATAN2((anything), NaN ) is NaN;
+ *	ATAN2(NAN , (anything) ) is NaN;
+ *	ATAN2(+-0, +(anything but NaN)) is +-0  ;
+ *	ATAN2(+-0, -(anything but NaN)) is +-pi ;
+ *	ATAN2(+-(anything but 0 and NaN), 0) is +-pi/2;
+ *	ATAN2(+-(anything but INF and NaN), +INF) is +-0 ;
+ *	ATAN2(+-(anything but INF and NaN), -INF) is +-pi;
+ *	ATAN2(+-INF,+INF ) is +-pi/4 ;
+ *	ATAN2(+-INF,-INF ) is +-3pi/4;
+ *	ATAN2(+-INF, (anything but,0,NaN, and INF)) is +-pi/2;
+ *
+ * Constants:
+ * The hexadecimal values are the intended ones for the following
+ * constants. The decimal values may be used, provided that the
+ * compiler will convert from decimal to binary accurately enough
+ * to produce the hexadecimal values shown.
+ */
+
+#include "math.h"
+#include "math_private.h"
+
+#ifdef __STDC__
+static const long double
+#else
+static long double
+#endif
+tiny  = 1.0e-4900L,
+zero  = 0.0,
+pi_o_4  = 7.85398163397448309628202E-01L, /* 0x3FFE, 0xC90FDAA2, 0x2168C235 */
+pi_o_2  = 1.5707963267948966192564E+00L,  /* 0x3FFF, 0xC90FDAA2, 0x2168C235 */
+pi      = 3.14159265358979323851281E+00L, /* 0x4000, 0xC90FDAA2, 0x2168C235 */
+pi_lo   = -5.01655761266833202345176e-20L;/* 0xBFBE, 0xECE675D1, 0xFC8F8CBB */
+
+#ifdef __STDC__
+	long double __ieee754_atan2l(long double y, long double x)
+#else
+	long double __ieee754_atan2l(y,x)
+	long double  y,x;
+#endif
+{
+	long double z;
+	int32_t k,m,hx,hy,ix,iy;
+	u_int32_t sx,sy,lx,ly;
+
+	EXTRACT_LDOUBLE_WORDS(sx,hx,lx,x);
+	ix = sx&0x7fff;
+	lx |= hx & 0x7fffffff;
+	EXTRACT_LDOUBLE_WORDS(sy,hy,ly,y);
+	iy = sy&0x7fff;
+	ly |= hy & 0x7fffffff;
+	if(((2*ix|((lx|-lx)>>31))>0xfffe)||
+	   ((2*iy|((ly|-ly)>>31))>0xfffe))	/* x or y is NaN */
+	   return x+y;
+	if((sx-0x3fff|lx)==0) return __atanl(y);   /* x=1.0 */
+	m = ((sy>>15)&1)|((sx>>14)&2);	/* 2*sign(x)+sign(y) */
+
+    /* when y = 0 */
+	if((iy|ly)==0) {
+	    switch(m) {
+		case 0:
+		case 1: return y; 	/* atan(+-0,+anything)=+-0 */
+		case 2: return  pi+tiny;/* atan(+0,-anything) = pi */
+		case 3: return -pi-tiny;/* atan(-0,-anything) =-pi */
+	    }
+	}
+    /* when x = 0 */
+	if((ix|lx)==0) return (sy>=0x8000)?  -pi_o_2-tiny: pi_o_2+tiny;
+
+    /* when x is INF */
+	if(ix==0x7fff) {
+	    if(iy==0x7fff) {
+		switch(m) {
+		    case 0: return  pi_o_4+tiny;/* atan(+INF,+INF) */
+		    case 1: return -pi_o_4-tiny;/* atan(-INF,+INF) */
+		    case 2: return  3.0*pi_o_4+tiny;/*atan(+INF,-INF)*/
+		    case 3: return -3.0*pi_o_4-tiny;/*atan(-INF,-INF)*/
+		}
+	    } else {
+		switch(m) {
+		    case 0: return  zero  ;	/* atan(+...,+INF) */
+		    case 1: return -zero  ;	/* atan(-...,+INF) */
+		    case 2: return  pi+tiny  ;	/* atan(+...,-INF) */
+		    case 3: return -pi-tiny  ;	/* atan(-...,-INF) */
+		}
+	    }
+	}
+    /* when y is INF */
+	if(iy==0x7fff) return (sy>=0x8000)? -pi_o_2-tiny: pi_o_2+tiny;
+
+    /* compute y/x */
+	k = sy-sx;
+	if(k > 70) z=pi_o_2+0.5*pi_lo; 	/* |y/x| >  2**70 */
+	else if(sx>=0x8000&&k<-70) z=0.0; 	/* |y|/x < -2**70 */
+	else z=__atanl(fabsl(y/x));	/* safe to do y/x */
+	switch (m) {
+	    case 0: return       z  ;	/* atan(+,+) */
+	    case 1: {
+	    	      u_int32_t sz;
+		      GET_LDOUBLE_EXP(sz,z);
+		      SET_LDOUBLE_EXP(z,sz ^ 0x8000);
+		    }
+		    return       z  ;	/* atan(-,+) */
+	    case 2: return  pi-(z-pi_lo);/* atan(+,-) */
+	    default: /* case 3 */
+	    	    return  (z-pi_lo)-pi;/* atan(-,-) */
+	}
+}