Added atan implementation from uClibc
authorSam Lantinga <slouken@libsdl.org>
Sun, 29 Aug 2010 16:51:48 -0700
changeset 487367ad1c88dda0
parent 4872 231f8a1c5edd
child 4874 8288636b861d
Added atan implementation from uClibc
configure.in
include/SDL_config.h.in
include/SDL_stdinc.h
src/libm/math.h
src/libm/s_atan.c
     1.1 --- a/configure.in	Sun Aug 29 16:28:04 2010 -0700
     1.2 +++ b/configure.in	Sun Aug 29 16:51:48 2010 -0700
     1.3 @@ -235,7 +235,7 @@
     1.4      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)
     1.5  
     1.6      AC_CHECK_LIB(m, pow, [LIBS="$LIBS -lm"; EXTRA_LDFLAGS="$EXTRA_LDFLAGS -lm"])
     1.7 -    AC_CHECK_FUNCS(atan2 ceil copysign cos cosf fabs floor log pow scalbn sin sinf sqrt)
     1.8 +    AC_CHECK_FUNCS(atan atan2 ceil copysign cos cosf fabs floor log pow scalbn sin sinf sqrt)
     1.9  
    1.10      AC_CHECK_LIB(iconv, libiconv_open, [LIBS="$LIBS -liconv"; EXTRA_LDFLAGS="$EXTRA_LDFLAGS -liconv"])
    1.11      AC_CHECK_FUNCS(iconv)
     2.1 --- a/include/SDL_config.h.in	Sun Aug 29 16:28:04 2010 -0700
     2.2 +++ b/include/SDL_config.h.in	Sun Aug 29 16:51:48 2010 -0700
     2.3 @@ -136,6 +136,7 @@
     2.4  #undef HAVE_SNPRINTF
     2.5  #undef HAVE_VSNPRINTF
     2.6  #undef HAVE_M_PI
     2.7 +#undef HAVE_ATAN
     2.8  #undef HAVE_ATAN2
     2.9  #undef HAVE_CEIL
    2.10  #undef HAVE_COPYSIGN
     3.1 --- a/include/SDL_stdinc.h	Sun Aug 29 16:28:04 2010 -0700
     3.2 +++ b/include/SDL_stdinc.h	Sun Aug 29 16:51:48 2010 -0700
     3.3 @@ -694,6 +694,12 @@
     3.4  #define M_PI    3.14159265358979323846264338327950288   /* pi */
     3.5  #endif
     3.6  
     3.7 +#ifdef HAVE_ATAN
     3.8 +#define SDL_atan        atan
     3.9 +#else
    3.10 +extern DECLSPEC double SDLCALL SDL_atan(double x);
    3.11 +#endif
    3.12 +
    3.13  #ifdef HAVE_ATAN2
    3.14  #define SDL_atan2       atan2
    3.15  #else
     4.1 --- a/src/libm/math.h	Sun Aug 29 16:28:04 2010 -0700
     4.2 +++ b/src/libm/math.h	Sun Aug 29 16:51:48 2010 -0700
     4.3 @@ -24,6 +24,12 @@
     4.4  
     4.5  /* Math routines from uClibc: http://www.uclibc.org */
     4.6  
     4.7 +#ifdef HAVE_ATAN
     4.8 +#define atan            SDL_uclibc_atan
     4.9 +#else
    4.10 +#define atan            SDL_atan
    4.11 +#endif
    4.12 +
    4.13  #ifndef HAVE_ATAN2
    4.14  #define __ieee754_atan2 SDL_atan2
    4.15  #endif
     5.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     5.2 +++ b/src/libm/s_atan.c	Sun Aug 29 16:51:48 2010 -0700
     5.3 @@ -0,0 +1,114 @@
     5.4 +/*
     5.5 + * ====================================================
     5.6 + * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
     5.7 + *
     5.8 + * Developed at SunPro, a Sun Microsystems, Inc. business.
     5.9 + * Permission to use, copy, modify, and distribute this
    5.10 + * software is freely granted, provided that this notice
    5.11 + * is preserved.
    5.12 + * ====================================================
    5.13 + */
    5.14 +
    5.15 +/* atan(x)
    5.16 + * Method
    5.17 + *   1. Reduce x to positive by atan(x) = -atan(-x).
    5.18 + *   2. According to the integer k=4t+0.25 chopped, t=x, the argument
    5.19 + *      is further reduced to one of the following intervals and the
    5.20 + *      arctangent of t is evaluated by the corresponding formula:
    5.21 + *
    5.22 + *      [0,7/16]      atan(x) = t-t^3*(a1+t^2*(a2+...(a10+t^2*a11)...)
    5.23 + *      [7/16,11/16]  atan(x) = atan(1/2) + atan( (t-0.5)/(1+t/2) )
    5.24 + *      [11/16.19/16] atan(x) = atan( 1 ) + atan( (t-1)/(1+t) )
    5.25 + *      [19/16,39/16] atan(x) = atan(3/2) + atan( (t-1.5)/(1+1.5t) )
    5.26 + *      [39/16,INF]   atan(x) = atan(INF) + atan( -1/t )
    5.27 + *
    5.28 + * Constants:
    5.29 + * The hexadecimal values are the intended ones for the following
    5.30 + * constants. The decimal values may be used, provided that the
    5.31 + * compiler will convert from decimal to binary accurately enough
    5.32 + * to produce the hexadecimal values shown.
    5.33 + */
    5.34 +
    5.35 +#include "math.h"
    5.36 +#include "math_private.h"
    5.37 +
    5.38 +static const double atanhi[] = {
    5.39 +  4.63647609000806093515e-01, /* atan(0.5)hi 0x3FDDAC67, 0x0561BB4F */
    5.40 +  7.85398163397448278999e-01, /* atan(1.0)hi 0x3FE921FB, 0x54442D18 */
    5.41 +  9.82793723247329054082e-01, /* atan(1.5)hi 0x3FEF730B, 0xD281F69B */
    5.42 +  1.57079632679489655800e+00, /* atan(inf)hi 0x3FF921FB, 0x54442D18 */
    5.43 +};
    5.44 +
    5.45 +static const double atanlo[] = {
    5.46 +  2.26987774529616870924e-17, /* atan(0.5)lo 0x3C7A2B7F, 0x222F65E2 */
    5.47 +  3.06161699786838301793e-17, /* atan(1.0)lo 0x3C81A626, 0x33145C07 */
    5.48 +  1.39033110312309984516e-17, /* atan(1.5)lo 0x3C700788, 0x7AF0CBBD */
    5.49 +  6.12323399573676603587e-17, /* atan(inf)lo 0x3C91A626, 0x33145C07 */
    5.50 +};
    5.51 +
    5.52 +static const double aT[] = {
    5.53 +  3.33333333333329318027e-01, /* 0x3FD55555, 0x5555550D */
    5.54 + -1.99999999998764832476e-01, /* 0xBFC99999, 0x9998EBC4 */
    5.55 +  1.42857142725034663711e-01, /* 0x3FC24924, 0x920083FF */
    5.56 + -1.11111104054623557880e-01, /* 0xBFBC71C6, 0xFE231671 */
    5.57 +  9.09088713343650656196e-02, /* 0x3FB745CD, 0xC54C206E */
    5.58 + -7.69187620504482999495e-02, /* 0xBFB3B0F2, 0xAF749A6D */
    5.59 +  6.66107313738753120669e-02, /* 0x3FB10D66, 0xA0D03D51 */
    5.60 + -5.83357013379057348645e-02, /* 0xBFADDE2D, 0x52DEFD9A */
    5.61 +  4.97687799461593236017e-02, /* 0x3FA97B4B, 0x24760DEB */
    5.62 + -3.65315727442169155270e-02, /* 0xBFA2B444, 0x2C6A6C2F */
    5.63 +  1.62858201153657823623e-02, /* 0x3F90AD3A, 0xE322DA11 */
    5.64 +};
    5.65 +
    5.66 +static const double
    5.67 +one   = 1.0,
    5.68 +huge   = 1.0e300;
    5.69 +
    5.70 +double atan(double x)
    5.71 +{
    5.72 +	double w,s1,s2,z;
    5.73 +	int32_t ix,hx,id;
    5.74 +
    5.75 +	GET_HIGH_WORD(hx,x);
    5.76 +	ix = hx&0x7fffffff;
    5.77 +	if(ix>=0x44100000) {	/* if |x| >= 2^66 */
    5.78 +	    u_int32_t low;
    5.79 +	    GET_LOW_WORD(low,x);
    5.80 +	    if(ix>0x7ff00000||
    5.81 +		(ix==0x7ff00000&&(low!=0)))
    5.82 +		return x+x;		/* NaN */
    5.83 +	    if(hx>0) return  atanhi[3]+atanlo[3];
    5.84 +	    else     return -atanhi[3]-atanlo[3];
    5.85 +	} if (ix < 0x3fdc0000) {	/* |x| < 0.4375 */
    5.86 +	    if (ix < 0x3e200000) {	/* |x| < 2^-29 */
    5.87 +		if(huge+x>one) return x;	/* raise inexact */
    5.88 +	    }
    5.89 +	    id = -1;
    5.90 +	} else {
    5.91 +	x = fabs(x);
    5.92 +	if (ix < 0x3ff30000) {		/* |x| < 1.1875 */
    5.93 +	    if (ix < 0x3fe60000) {	/* 7/16 <=|x|<11/16 */
    5.94 +		id = 0; x = (2.0*x-one)/(2.0+x);
    5.95 +	    } else {			/* 11/16<=|x|< 19/16 */
    5.96 +		id = 1; x  = (x-one)/(x+one);
    5.97 +	    }
    5.98 +	} else {
    5.99 +	    if (ix < 0x40038000) {	/* |x| < 2.4375 */
   5.100 +		id = 2; x  = (x-1.5)/(one+1.5*x);
   5.101 +	    } else {			/* 2.4375 <= |x| < 2^66 */
   5.102 +		id = 3; x  = -1.0/x;
   5.103 +	    }
   5.104 +	}}
   5.105 +    /* end of argument reduction */
   5.106 +	z = x*x;
   5.107 +	w = z*z;
   5.108 +    /* break sum from i=0 to 10 aT[i]z**(i+1) into odd and even poly */
   5.109 +	s1 = z*(aT[0]+w*(aT[2]+w*(aT[4]+w*(aT[6]+w*(aT[8]+w*aT[10])))));
   5.110 +	s2 = w*(aT[1]+w*(aT[3]+w*(aT[5]+w*(aT[7]+w*aT[9]))));
   5.111 +	if (id<0) return x - x*(s1+s2);
   5.112 +	else {
   5.113 +	    z = atanhi[id] - ((x*(s1+s2) - atanlo[id]) - x);
   5.114 +	    return (hx<0)? -z:z;
   5.115 +	}
   5.116 +}
   5.117 +libm_hidden_def(atan)