Added atan2 implementation from uClibc
authorSam Lantinga <slouken@libsdl.org>
Sun, 29 Aug 2010 16:05:34 -0700
changeset 4870 d275c95ddc05
parent 4869 2b1bcf74e4c4
child 4871 81a6a9f396ba
Added atan2 implementation from uClibc
configure.in
include/SDL_config.h.in
include/SDL_stdinc.h
src/libm/e_atan2.c
src/libm/math.h
--- a/configure.in	Sun Aug 29 15:26:12 2010 -0700
+++ b/configure.in	Sun Aug 29 16:05:34 2010 -0700
@@ -235,7 +235,7 @@
     AC_CHECK_FUNCS(malloc calloc realloc free getenv setenv putenv unsetenv qsort abs bcopy memset memcpy memmove strlen strlcpy strlcat strdup _strrev _strupr _strlwr strchr strrchr strstr itoa _ltoa _uitoa _ultoa strtol strtoul _i64toa _ui64toa strtoll strtoull atoi atof strcmp strncmp _stricmp strcasecmp _strnicmp strncasecmp sscanf snprintf vsnprintf sigaction setjmp nanosleep sysconf sysctlbyname)
 
     AC_CHECK_LIB(m, pow, [LIBS="$LIBS -lm"; EXTRA_LDFLAGS="$EXTRA_LDFLAGS -lm"])
-    AC_CHECK_FUNCS(ceil copysign cos cosf fabs floor log pow scalbn sin sinf sqrt)
+    AC_CHECK_FUNCS(atan2 ceil copysign cos cosf fabs floor log pow scalbn sin sinf sqrt)
 
     AC_CHECK_LIB(iconv, libiconv_open, [LIBS="$LIBS -liconv"; EXTRA_LDFLAGS="$EXTRA_LDFLAGS -liconv"])
     AC_CHECK_FUNCS(iconv)
--- a/include/SDL_config.h.in	Sun Aug 29 15:26:12 2010 -0700
+++ b/include/SDL_config.h.in	Sun Aug 29 16:05:34 2010 -0700
@@ -136,6 +136,7 @@
 #undef HAVE_SNPRINTF
 #undef HAVE_VSNPRINTF
 #undef HAVE_M_PI
+#undef HAVE_ATAN2
 #undef HAVE_CEIL
 #undef HAVE_COPYSIGN
 #undef HAVE_COS
--- a/include/SDL_stdinc.h	Sun Aug 29 15:26:12 2010 -0700
+++ b/include/SDL_stdinc.h	Sun Aug 29 16:05:34 2010 -0700
@@ -694,6 +694,12 @@
 #define M_PI    3.14159265358979323846264338327950288   /* pi */
 #endif
 
+#ifdef HAVE_ATAN2
+#define SDL_atan2       atan2
+#else
+extern DECLSPEC double SDLCALL SDL_atan2(double y, double x);
+#endif
+
 #ifdef HAVE_CEIL
 #define SDL_ceil        ceil
 #else
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/libm/e_atan2.c	Sun Aug 29 16:05:34 2010 -0700
@@ -0,0 +1,116 @@
+/*
+ * ====================================================
+ * 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.
+ * ====================================================
+ */
+
+/* __ieee754_atan2(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"
+
+static const double
+tiny  = 1.0e-300,
+zero  = 0.0,
+pi_o_4  = 7.8539816339744827900E-01, /* 0x3FE921FB, 0x54442D18 */
+pi_o_2  = 1.5707963267948965580E+00, /* 0x3FF921FB, 0x54442D18 */
+pi      = 3.1415926535897931160E+00, /* 0x400921FB, 0x54442D18 */
+pi_lo   = 1.2246467991473531772E-16; /* 0x3CA1A626, 0x33145C07 */
+
+double attribute_hidden __ieee754_atan2(double y, double x)
+{
+	double z;
+	int32_t k,m,hx,hy,ix,iy;
+	u_int32_t lx,ly;
+
+	EXTRACT_WORDS(hx,lx,x);
+	ix = hx&0x7fffffff;
+	EXTRACT_WORDS(hy,ly,y);
+	iy = hy&0x7fffffff;
+	if(((ix|((lx|-lx)>>31))>0x7ff00000)||
+	   ((iy|((ly|-ly)>>31))>0x7ff00000))	/* x or y is NaN */
+	   return x+y;
+	if(((hx-0x3ff00000)|lx)==0) return atan(y);   /* x=1.0 */
+	m = ((hy>>31)&1)|((hx>>30)&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 (hy<0)?  -pi_o_2-tiny: pi_o_2+tiny;
+
+    /* when x is INF */
+	if(ix==0x7ff00000) {
+	    if(iy==0x7ff00000) {
+		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==0x7ff00000) return (hy<0)? -pi_o_2-tiny: pi_o_2+tiny;
+
+    /* compute y/x */
+	k = (iy-ix)>>20;
+	if(k > 60) z=pi_o_2+0.5*pi_lo; 	/* |y/x| >  2**60 */
+	else if(hx<0&&k<-60) z=0.0; 	/* |y|/x < -2**60 */
+	else z=atan(fabs(y/x));		/* safe to do y/x */
+	switch (m) {
+	    case 0: return       z  ;	/* atan(+,+) */
+	    case 1: {
+	    	      u_int32_t zh;
+		      GET_HIGH_WORD(zh,z);
+		      SET_HIGH_WORD(z,zh ^ 0x80000000);
+		    }
+		    return       z  ;	/* atan(-,+) */
+	    case 2: return  pi-(z-pi_lo);/* atan(+,-) */
+	    default: /* case 3 */
+	    	    return  (z-pi_lo)-pi;/* atan(-,-) */
+	}
+}
--- a/src/libm/math.h	Sun Aug 29 15:26:12 2010 -0700
+++ b/src/libm/math.h	Sun Aug 29 16:05:34 2010 -0700
@@ -24,6 +24,10 @@
 
 /* Math routines from uClibc: http://www.uclibc.org */
 
+#ifndef HAVE_ATAN2
+#define __ieee754_atan2 SDL_atan2
+#endif
+
 #ifdef HAVE_COPYSIGN
 #define copysign        SDL_uclibc_copysign
 #else