12116Sjkh/* e_atan2f.c -- float version of e_atan2.c.
22116Sjkh * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
32116Sjkh */
42116Sjkh
52116Sjkh/*
62116Sjkh * ====================================================
72116Sjkh * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
82116Sjkh *
92116Sjkh * Developed at SunPro, a Sun Microsystems, Inc. business.
102116Sjkh * Permission to use, copy, modify, and distribute this
118870Srgrimes * software is freely granted, provided that this notice
122116Sjkh * is preserved.
132116Sjkh * ====================================================
142116Sjkh */
152116Sjkh
16176451Sdas#include <sys/cdefs.h>
17176451Sdas__FBSDID("$FreeBSD$");
182116Sjkh
192116Sjkh#include "math.h"
202116Sjkh#include "math_private.h"
212116Sjkh
22181062Sdasstatic volatile float
23181062Sdastiny  = 1.0e-30;
248870Srgrimesstatic const float
252116Sjkhzero  = 0.0,
262116Sjkhpi_o_4  = 7.8539818525e-01, /* 0x3f490fdb */
272116Sjkhpi_o_2  = 1.5707963705e+00, /* 0x3fc90fdb */
28181062Sdaspi      = 3.1415927410e+00; /* 0x40490fdb */
29181062Sdasstatic volatile float
30130003Sbdepi_lo   = -8.7422776573e-08; /* 0xb3bbbd2e */
312116Sjkh
3297407Salfredfloat
3397407Salfred__ieee754_atan2f(float y, float x)
348870Srgrimes{
352116Sjkh	float z;
362116Sjkh	int32_t k,m,hx,hy,ix,iy;
372116Sjkh
382116Sjkh	GET_FLOAT_WORD(hx,x);
392116Sjkh	ix = hx&0x7fffffff;
402116Sjkh	GET_FLOAT_WORD(hy,y);
412116Sjkh	iy = hy&0x7fffffff;
422116Sjkh	if((ix>0x7f800000)||
432116Sjkh	   (iy>0x7f800000))	/* x or y is NaN */
442116Sjkh	   return x+y;
452116Sjkh	if(hx==0x3f800000) return atanf(y);   /* x=1.0 */
462116Sjkh	m = ((hy>>31)&1)|((hx>>30)&2);	/* 2*sign(x)+sign(y) */
472116Sjkh
482116Sjkh    /* when y = 0 */
492116Sjkh	if(iy==0) {
502116Sjkh	    switch(m) {
518870Srgrimes		case 0:
522116Sjkh		case 1: return y; 	/* atan(+-0,+anything)=+-0 */
532116Sjkh		case 2: return  pi+tiny;/* atan(+0,-anything) = pi */
542116Sjkh		case 3: return -pi-tiny;/* atan(-0,-anything) =-pi */
552116Sjkh	    }
562116Sjkh	}
572116Sjkh    /* when x = 0 */
582116Sjkh	if(ix==0) return (hy<0)?  -pi_o_2-tiny: pi_o_2+tiny;
598870Srgrimes
602116Sjkh    /* when x is INF */
612116Sjkh	if(ix==0x7f800000) {
622116Sjkh	    if(iy==0x7f800000) {
632116Sjkh		switch(m) {
642116Sjkh		    case 0: return  pi_o_4+tiny;/* atan(+INF,+INF) */
652116Sjkh		    case 1: return -pi_o_4-tiny;/* atan(-INF,+INF) */
662116Sjkh		    case 2: return  (float)3.0*pi_o_4+tiny;/*atan(+INF,-INF)*/
672116Sjkh		    case 3: return (float)-3.0*pi_o_4-tiny;/*atan(-INF,-INF)*/
682116Sjkh		}
692116Sjkh	    } else {
702116Sjkh		switch(m) {
712116Sjkh		    case 0: return  zero  ;	/* atan(+...,+INF) */
722116Sjkh		    case 1: return -zero  ;	/* atan(-...,+INF) */
732116Sjkh		    case 2: return  pi+tiny  ;	/* atan(+...,-INF) */
742116Sjkh		    case 3: return -pi-tiny  ;	/* atan(-...,-INF) */
752116Sjkh		}
762116Sjkh	    }
772116Sjkh	}
782116Sjkh    /* when y is INF */
792116Sjkh	if(iy==0x7f800000) return (hy<0)? -pi_o_2-tiny: pi_o_2+tiny;
802116Sjkh
812116Sjkh    /* compute y/x */
822116Sjkh	k = (iy-ix)>>23;
83181204Sdas	if(k > 26) {			/* |y/x| >  2**26 */
84181204Sdas	    z=pi_o_2+(float)0.5*pi_lo;
85181204Sdas	    m&=1;
86181204Sdas	}
87181257Sdas	else if(k<-26&&hx<0) z=0.0; 	/* 0 > |y|/x > -2**-26 */
882116Sjkh	else z=atanf(fabsf(y/x));	/* safe to do y/x */
892116Sjkh	switch (m) {
902116Sjkh	    case 0: return       z  ;	/* atan(+,+) */
91181204Sdas	    case 1: return      -z  ;	/* atan(-,+) */
922116Sjkh	    case 2: return  pi-(z-pi_lo);/* atan(+,-) */
932116Sjkh	    default: /* case 3 */
942116Sjkh	    	    return  (z-pi_lo)-pi;/* atan(-,-) */
952116Sjkh	}
962116Sjkh}
97