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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libm/] [math/] [ef_atan2.c] - Blame information for rev 207

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1 207 jeremybenn
/* ef_atan2.c -- float version of e_atan2.c.
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 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
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 */
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/*
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 * ====================================================
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 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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 *
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 * Developed at SunPro, a Sun Microsystems, Inc. business.
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 * Permission to use, copy, modify, and distribute this
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 * software is freely granted, provided that this notice
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 * is preserved.
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 * ====================================================
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 *
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 */
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#include "fdlibm.h"
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#ifdef __STDC__
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static const float
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#else
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static float
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#endif
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tiny  = 1.0e-30,
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zero  = 0.0,
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pi_o_4  = 7.8539818525e-01, /* 0x3f490fdb */
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pi_o_2  = 1.5707963705e+00, /* 0x3fc90fdb */
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pi      = 3.1415927410e+00,  /* 0x40490fdb */
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pi_lo   = -8.7422776573e-08; /* 0xb3bbbd2e */
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#ifdef __STDC__
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        float __ieee754_atan2f(float y, float x)
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#else
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        float __ieee754_atan2f(y,x)
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        float  y,x;
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#endif
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{
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        float z;
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        __int32_t k,m,hx,hy,ix,iy;
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        GET_FLOAT_WORD(hx,x);
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        ix = hx&0x7fffffff;
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        GET_FLOAT_WORD(hy,y);
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        iy = hy&0x7fffffff;
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        if(FLT_UWORD_IS_NAN(ix)||
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           FLT_UWORD_IS_NAN(iy))        /* x or y is NaN */
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           return x+y;
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        if(hx==0x3f800000) return atanf(y);   /* x=1.0 */
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        m = ((hy>>31)&1)|((hx>>30)&2);  /* 2*sign(x)+sign(y) */
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    /* when y = 0 */
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        if(FLT_UWORD_IS_ZERO(iy)) {
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            switch(m) {
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                case 0:
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                case 1: return y;       /* atan(+-0,+anything)=+-0 */
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                case 2: return  pi+tiny;/* atan(+0,-anything) = pi */
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                case 3: return -pi-tiny;/* atan(-0,-anything) =-pi */
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            }
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        }
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    /* when x = 0 */
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        if(FLT_UWORD_IS_ZERO(ix)) return (hy<0)?  -pi_o_2-tiny: pi_o_2+tiny;
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    /* when x is INF */
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        if(FLT_UWORD_IS_INFINITE(ix)) {
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            if(FLT_UWORD_IS_INFINITE(iy)) {
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                switch(m) {
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                    case 0: return  pi_o_4+tiny;/* atan(+INF,+INF) */
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                    case 1: return -pi_o_4-tiny;/* atan(-INF,+INF) */
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                    case 2: return  (float)3.0*pi_o_4+tiny;/*atan(+INF,-INF)*/
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                    case 3: return (float)-3.0*pi_o_4-tiny;/*atan(-INF,-INF)*/
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                }
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            } else {
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                switch(m) {
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                    case 0: return  zero  ;      /* atan(+...,+INF) */
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                    case 1: return -zero  ;     /* atan(-...,+INF) */
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                    case 2: return  pi+tiny  ;  /* atan(+...,-INF) */
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                    case 3: return -pi-tiny  ;  /* atan(-...,-INF) */
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                }
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            }
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        }
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    /* when y is INF */
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        if(FLT_UWORD_IS_INFINITE(iy)) return (hy<0)? -pi_o_2-tiny: pi_o_2+tiny;
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    /* compute y/x */
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        k = (iy-ix)>>23;
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        if(k > 60) z=pi_o_2+(float)0.5*pi_lo;   /* |y/x| >  2**60 */
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        else if(hx<0&&k<-60) z=0.0;      /* |y|/x < -2**60 */
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        else z=atanf(fabsf(y/x));       /* safe to do y/x */
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        switch (m) {
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            case 0: return       z  ;    /* atan(+,+) */
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            case 1: {
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                      __uint32_t zh;
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                      GET_FLOAT_WORD(zh,z);
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                      SET_FLOAT_WORD(z,zh ^ 0x80000000);
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                    }
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                    return       z  ;   /* atan(-,+) */
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            case 2: return  pi-(z-pi_lo);/* atan(+,-) */
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            default: /* case 3 */
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                    return  (z-pi_lo)-pi;/* atan(-,-) */
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        }
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}

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