From 210300e31143400856c4075803085a9127605c51 Mon Sep 17 00:00:00 2001 From: Sam Lantinga Date: Sun, 29 Aug 2010 16:05:34 -0700 Subject: [PATCH] Added atan2 implementation from uClibc --- configure.in | 2 +- include/SDL_config.h.in | 1 + include/SDL_stdinc.h | 6 +++ src/libm/e_atan2.c | 116 ++++++++++++++++++++++++++++++++++++++++ src/libm/math.h | 4 ++ 5 files changed, 128 insertions(+), 1 deletion(-) create mode 100644 src/libm/e_atan2.c diff --git a/configure.in b/configure.in index 4fba7def0..fa13d5abd 100644 --- a/configure.in +++ b/configure.in @@ -235,7 +235,7 @@ if test x$enable_libc = xyes; then AC_CHECK_FUNCS(malloc calloc realloc free getenv setenv putenv unsetenv qsort abs bcopy memset memcpy memmove strlen strlcpy strlcat strdup _strrev _strupr _strlwr strchr strrchr strstr itoa _ltoa _uitoa _ultoa strtol strtoul _i64toa _ui64toa strtoll strtoull atoi atof strcmp strncmp _stricmp strcasecmp _strnicmp strncasecmp sscanf snprintf vsnprintf sigaction setjmp nanosleep sysconf sysctlbyname) AC_CHECK_LIB(m, pow, [LIBS="$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) diff --git a/include/SDL_config.h.in b/include/SDL_config.h.in index aa098aa66..c84d5c511 100644 --- a/include/SDL_config.h.in +++ b/include/SDL_config.h.in @@ -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 diff --git a/include/SDL_stdinc.h b/include/SDL_stdinc.h index b3328b154..7d17f6007 100644 --- a/include/SDL_stdinc.h +++ b/include/SDL_stdinc.h @@ -694,6 +694,12 @@ extern DECLSPEC int SDLCALL SDL_vsnprintf(char *text, size_t maxlen, #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 diff --git a/src/libm/e_atan2.c b/src/libm/e_atan2.c new file mode 100644 index 000000000..71c916d52 --- /dev/null +++ b/src/libm/e_atan2.c @@ -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(-,-) */ + } +} diff --git a/src/libm/math.h b/src/libm/math.h index 1cdf82f0e..e00883e00 100644 --- a/src/libm/math.h +++ b/src/libm/math.h @@ -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