Fix a bug about the iSCSI DHCP dependency issue.

[mirror_edk2.git] / StdLib / LibC / Math / e_atan2.c

/* @(#)e_atan2.c 5.1 93/09/24 */\r
/*\r
 * ====================================================\r
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.\r
 *\r
 * Developed at SunPro, a Sun Microsystems, Inc. business.\r
 * Permission to use, copy, modify, and distribute this\r
 * software is freely granted, provided that this notice\r
 * is preserved.\r
 * ====================================================\r
 */\r
#include  <LibConfig.h>\r
#include  <sys/EfiCdefs.h>\r
#if defined(LIBM_SCCS) && !defined(lint)\r
__RCSID("$NetBSD: e_atan2.c,v 1.12 2002/05/26 22:01:48 wiz Exp $");\r
#endif\r
\r
#if defined(_MSC_VER)           /* Handle Microsoft VC++ compiler specifics. */\r
  // unary minus operator applied to unsigned type, result still unsigned\r
  #pragma warning ( disable : 4146 )\r
#endif\r
\r
/* __ieee754_atan2(y,x)\r
 * Method :\r
 *  1. Reduce y to positive by atan2(y,x)=-atan2(-y,x).\r
 *  2. Reduce x to positive by (if x and y are unexceptional):\r
 *    ARG (x+iy) = arctan(y/x)       ... if x > 0,\r
 *    ARG (x+iy) = pi - arctan[y/(-x)]   ... if x < 0,\r
 *\r
 * Special cases:\r
 *\r
 *  ATAN2((anything), NaN ) is NaN;\r
 *  ATAN2(NAN , (anything) ) is NaN;\r
 *  ATAN2(+-0, +(anything but NaN)) is +-0  ;\r
 *  ATAN2(+-0, -(anything but NaN)) is +-pi ;\r
 *  ATAN2(+-(anything but 0 and NaN), 0) is +-pi/2;\r
 *  ATAN2(+-(anything but INF and NaN), +INF) is +-0 ;\r
 *  ATAN2(+-(anything but INF and NaN), -INF) is +-pi;\r
 *  ATAN2(+-INF,+INF ) is +-pi/4 ;\r
 *  ATAN2(+-INF,-INF ) is +-3pi/4;\r
 *  ATAN2(+-INF, (anything but,0,NaN, and INF)) is +-pi/2;\r
 *\r
 * Constants:\r
 * The hexadecimal values are the intended ones for the following\r
 * constants. The decimal values may be used, provided that the\r
 * compiler will convert from decimal to binary accurately enough\r
 * to produce the hexadecimal values shown.\r
 */\r
\r
#include "math.h"\r
#include "math_private.h"\r
\r
static const double\r
tiny  = 1.0e-300,\r
zero  = 0.0,\r
pi_o_4  = 7.8539816339744827900E-01, /* 0x3FE921FB, 0x54442D18 */\r
pi_o_2  = 1.5707963267948965580E+00, /* 0x3FF921FB, 0x54442D18 */\r
pi      = 3.1415926535897931160E+00, /* 0x400921FB, 0x54442D18 */\r
pi_lo   = 1.2246467991473531772E-16; /* 0x3CA1A626, 0x33145C07 */\r
\r
double\r
__ieee754_atan2(double y, double x)\r
{\r
  double z;\r
  int32_t k,m,hx,hy,ix,iy;\r
  u_int32_t lx,ly;\r
\r
  EXTRACT_WORDS(hx,lx,x);\r
  ix = hx&0x7fffffff;\r
  EXTRACT_WORDS(hy,ly,y);\r
  iy = hy&0x7fffffff;\r
  if(((ix|((lx|-lx)>>31))>0x7ff00000)||\r
     ((iy|((ly|-ly)>>31))>0x7ff00000))  /* x or y is NaN */\r
     return x+y;\r
  if(((hx-0x3ff00000)|lx)==0) return atan(y);   /* x=1.0 */\r
  m = ((hy>>31)&1)|((hx>>30)&2);  /* 2*sign(x)+sign(y) */\r
\r
    /* when y = 0 */\r
  if((iy|ly)==0) {\r
      switch(m) {\r
    case 0:\r
    case 1: return y;   /* atan(+-0,+anything)=+-0 */\r
    case 2: return  pi+tiny;/* atan(+0,-anything) = pi */\r
    case 3: return -pi-tiny;/* atan(-0,-anything) =-pi */\r
      }\r
  }\r
    /* when x = 0 */\r
  if((ix|lx)==0) return (hy<0)?  -pi_o_2-tiny: pi_o_2+tiny;\r
\r
    /* when x is INF */\r
  if(ix==0x7ff00000) {\r
      if(iy==0x7ff00000) {\r
    switch(m) {\r
        case 0: return  pi_o_4+tiny;/* atan(+INF,+INF) */\r
        case 1: return -pi_o_4-tiny;/* atan(-INF,+INF) */\r
        case 2: return  3.0*pi_o_4+tiny;/*atan(+INF,-INF)*/\r
        case 3: return -3.0*pi_o_4-tiny;/*atan(-INF,-INF)*/\r
    }\r
      } else {\r
    switch(m) {\r
        case 0: return  zero  ; /* atan(+...,+INF) */\r
        case 1: return -zero  ; /* atan(-...,+INF) */\r
        case 2: return  pi+tiny  ;  /* atan(+...,-INF) */\r
        case 3: return -pi-tiny  ;  /* atan(-...,-INF) */\r
    }\r
      }\r
  }\r
    /* when y is INF */\r
  if(iy==0x7ff00000) return (hy<0)? -pi_o_2-tiny: pi_o_2+tiny;\r
\r
    /* compute y/x */\r
  k = (iy-ix)>>20;\r
  if(k > 60) z=pi_o_2+0.5*pi_lo;  /* |y/x| >  2**60 */\r
  else if(hx<0&&k<-60) z=0.0;   /* |y|/x < -2**60 */\r
  else z=atan(fabs(y/x));   /* safe to do y/x */\r
  switch (m) {\r
      case 0: return       z  ; /* atan(+,+) */\r
      case 1: {\r
              u_int32_t zh;\r
          GET_HIGH_WORD(zh,z);\r
          SET_HIGH_WORD(z,zh ^ 0x80000000);\r
        }\r
        return       z  ; /* atan(-,+) */\r
      case 2: return  pi-(z-pi_lo);/* atan(+,-) */\r
      default: /* case 3 */\r
            return  (z-pi_lo)-pi;/* atan(-,-) */\r
  }\r
}\r