/* e_atan2f.c -- float version of e_atan2.c.

 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@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.

 * ====================================================

 */

#include <math.h>

#include <math_private.h>

static const float

tiny  = 1.0e-30,

zero  = 0.0,

pi_o_4  = 7.8539818525e-01,  /* 0x3f490fdb */

pi_o_2  = 1.5707963705e+00,  /* 0x3fc90fdb */

pi      = 3.1415927410e+00,  /* 0x40490fdb */

pi_lo   = -8.7422776573e-08; /* 0xb3bbbd2e */

float

__ieee754_atan2f (float y, float x)

{

	float z;

	int32_t k,m,hx,hy,ix,iy;

	GET_FLOAT_WORD(hx,x);

	ix = hx&0x7fffffff;

	GET_FLOAT_WORD(hy,y);

	iy = hy&0x7fffffff;

	if((ix>0x7f800000)||

	   (iy>0x7f800000))	/* x or y is NaN */

	   return x+y;

	if(hx==0x3f800000) return __atanf(y);   /* x=1.0 */

	m = ((hy>>31)&1)|((hx>>30)&2;;	/* 2*sign(x)+sign(y) */

    /* when y = 0 */

	if(iy==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==0) return (hy<0)?  -pi_o_2-tiny: pi_o_2+tiny;

    /* when x is INF */

	if(ix==0x7f800000) {

	    if(iy==0x7f800000) {

		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  (float)3.0*pi_o_4+tiny;/*atan(+INF,-INF)*/

		    case 3: return (float)-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==0x7f800000) return (hy<0)? -pi_o_2-tiny: pi_o_2+tiny;

    /* compute y/x */

	k = (iy-ix)>>23;

	if(k > 60) z=pi_o_2+(float)0.5*pi_lo;	/* |y/x| >  2**60 */

	else if(hx<0&&k<-60) z=0.0;	/* |y|/x < -2**60 */

	else z=__atanf(fabsf(y/x));	/* safe to do y/x */

	switch (m) {

	    case 0: return       z  ;	/* atan(+,+) */

	    case 1: {

		      uint32_t zh;

		      GET_FLOAT_WORD(zh,z);

		      SET_FLOAT_WORD(z,zh ^ 0x80000000);

		    }

		    return       z  ;	/* atan(-,+) */

	    case 2: return  pi-(z-pi_lo);/* atan(+,-) */

	    default: /* case 3 */

		    return  (z-pi_lo)-pi;/* atan(-,-) */

	}

}

strong_alias (__ieee754_atan2f, __atan2f_finite)