/* Copyright (C) 1993  Hongjiu Lu
   Changed by Olaf Flebbe for long double
This file is part of the Linux C Library.

The Linux C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.

The Linux C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Library General Public License for more details.  */

#include <ansidecl.h>
#include <fp.h>
#include <errno.h>
#include "mathl.h"

long double
DEFUN(acosl, (x), long double x)
{
  if (x <= -1.0L ) {
    if (x == -1.0L) {
      return 3.14159265358979323846L;
    }
    return __infnanl( EDOM);
  } 

  if (x >= 1.0L ) {
    if (x == 1.0L) {
      return 0.0L;
    }
    return __infnanl( EDOM);
  } 

  x = sqrtl ((1.0L - x) / (1.0L + x));
  __asm__ __volatile__ ("fpatan"
			:"=t" (x) : "0" (1.0L), "u" (x));
  return x + x;
}