/* Copyright (c) 2002,2007 Michael Stumpf

   Portions of documentation Copyright (c) 1990 - 1994
   The Regents of the University of California.

   All rights reserved.

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions are met:

   * Redistributions of source code must retain the above copyright
     notice, this list of conditions and the following disclaimer.

   * Redistributions in binary form must reproduce the above copyright
     notice, this list of conditions and the following disclaimer in
     the documentation and/or other materials provided with the
     distribution.

   * Neither the name of the copyright holders nor the names of
     contributors may be used to endorse or promote products derived
     from this software without specific prior written permission.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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  POSSIBILITY OF SUCH DAMAGE. */

/* $Id: math.h,v 1.21 2007/12/19 13:33:54 dmix Exp $ */

/*
   math.h - mathematical functions

   Author : Michael Stumpf
            Michael.Stumpf@t-online.de

   __ATTR_CONST__ added by marekm@linux.org.pl for functions
   that "do not examine any values except their arguments, and have
   no effects except the return value", for better optimization by gcc.
 */

#ifndef __MATH_H
#define __MATH_H

/** \file */
/** \defgroup avr_math <math.h>: Mathematics
    \code #include <math.h> \endcode

    This header file declares basic mathematics constants and
    functions.

    \par Notes:
    - In order to access the functions delcared herein, it is usually
      also required to additionally link against the library \c libm.a.
      See also the related \ref faq_libm "FAQ entry".
    - Math functions do not raise exceptions and do not change the
      \c errno variable. Therefore the majority of them are declared
      with const attribute, for better optimization by GCC.	*/

/**
   \ingroup avr_math

   The constant \c pi. */
#define M_PI 3.141592653589793238462643

/**
   \ingroup avr_math

   The square root of 2. */
#define M_SQRT2 1.4142135623730950488016887

/**
   \ingroup avr_math

   NAN constant. */
#define NAN	__builtin_nan("")

/**
   \ingroup avr_math

   INFINITY constant. */
#define INFINITY	__builtin_inf()

#ifndef __ATTR_CONST__
# define __ATTR_CONST__ __attribute__((__const__))
#endif

#ifdef __cplusplus
extern "C" {
#endif

  /**
     \ingroup avr_math

     The cos() function returns the cosine of \a __x, measured in radians.
  */
extern double cos(double __x) __ATTR_CONST__;

  /**
     \ingroup avr_math

     The fabs() function computes the absolute value of a floating-point
     number \a __x.
  */
extern double fabs(double __x) __ATTR_CONST__;
#if 0
/* fabs seems to be built in already */
extern inline double fabs( double __x )
  { double __res;
    __asm__ __volatile__ ("andi %D0,0x7F \n\t"
		: "=d" (__res) : "0" (__x) );
    return __res;
  }
#endif

  /**
     \ingroup avr_math

     The function fmod() returns the floating-point remainder of <em>__x /
     __y</em>.
  */
extern double fmod(double __x, double __y) __ATTR_CONST__;

  /**
     \ingroup avr_math

     The modf() function breaks the argument \a __x into integral and
     fractional parts, each of which has the same sign as the argument. 
     It stores the integral part as a double in the object pointed to by
     \a __iptr.

     The modf() function returns the signed fractional part of \a __x.
     
     \note
     This implementation skips writing by zero pointer.
  */
extern double modf(double __x, double *__iptr);

  /**
     \ingroup avr_math

     The sin() function returns the sine of \a __x, measured in radians.
  */
extern double sin(double __x) __ATTR_CONST__;

  /**
     \ingroup avr_math

     The sqrt() function returns the non-negative square root of \a __x.
  */
extern double sqrt(double __x) __ATTR_CONST__;

  /**
     \ingroup avr_math

     The tan() function returns the tangent of \a __x, measured in
     radians.
  */
extern double tan(double __x) __ATTR_CONST__;

  /**
     \ingroup avr_math

     The floor() function returns the largest integral value less than or
     equal to \a __x, expressed as a floating-point number.
  */
extern double floor(double __x) __ATTR_CONST__;

  /**
     \ingroup avr_math

     The ceil() function returns the smallest integral value greater than
     or equal to \a __x, expressed as a floating-point number.
  */
extern double ceil(double __x) __ATTR_CONST__;

  /**
     \ingroup avr_math

     The frexp() function breaks a floating-point number into a normalized
     fraction and an integral power of 2.  It stores the integer in the \c
     int object pointed to by \a __pexp.

     If \a __x is a normal float point number, the frexp() function
     returns the value \c v, such that \c v has a magnitude in the
     interval [1/2, 1) or zero, and \a __x equals \c v times 2 raised to
     the power \a __pexp. If \a __x is zero, both parts of the result are
     zero. If \a __x is not a finite number, the frexp() returns \a __x as
     is and stores 0 by \a __pexp.

     \note  This implementation permits a zero pointer as a directive to
     skip a storing the exponent.
  */
extern double frexp(double __x, int *__pexp);

  /**
     \ingroup avr_math

     The ldexp() function multiplies a floating-point number by an integral
     power of 2.

     The ldexp() function returns the value of \a __x times 2 raised to
     the power \a __exp.
  */
extern double ldexp(double __x, int __exp) __ATTR_CONST__;

  /**
     \ingroup avr_math

     The exp() function returns the exponential value of \a __x.
  */
extern double exp(double __x) __ATTR_CONST__;

  /**
     \ingroup avr_math

     The cosh() function returns the hyperbolic cosine of \a __x.
  */
extern double cosh(double __x) __ATTR_CONST__;

  /**
     \ingroup avr_math

     The sinh() function returns the hyperbolic sine of \a __x.
  */
extern double sinh(double __x) __ATTR_CONST__;

  /**
     \ingroup avr_math

     The tanh() function returns the hyperbolic tangent of \a __x.
  */
extern double tanh(double __x) __ATTR_CONST__;

  /**
     \ingroup avr_math

     The acos() function computes the principal value of the arc cosine of
     \a __x.  The returned value is in the range [0, pi] radians. A domain
     error occurs for arguments not in the range [-1, +1].
  */
extern double acos(double __x) __ATTR_CONST__;

  /**
     \ingroup avr_math

     The asin() function computes the principal value of the arc sine of
     \a __x.  The returned value is in the range [-pi/2, pi/2] radians. A
     domain error occurs for arguments not in the range [-1, +1].
  */
extern double asin(double __x) __ATTR_CONST__;

  /**
     \ingroup avr_math

     The atan() function computes the principal value of the arc tangent
     of \a __x.  The returned value is in the range [-pi/2, pi/2] radians.
  */
extern double atan(double __x) __ATTR_CONST__;

  /**
     \ingroup avr_math
     
     The atan2() function computes the principal value of the arc tangent
     of <em>__y / __x</em>, using the signs of both arguments to determine
     the quadrant of the return value.  The returned value is in the range
     [-pi, +pi] radians.
  */
extern double atan2(double __y, double __x) __ATTR_CONST__;

  /**
     \ingroup avr_math

     The log() function returns the natural logarithm of argument \a __x.
   */
extern double log(double __x) __ATTR_CONST__;

  /**
     \ingroup avr_math

     The log10() function returns the logarithm of argument \a __x to base
     10.
   */
extern double log10(double __x) __ATTR_CONST__;

  /**
     \ingroup avr_math

     The function pow() returns the value of \a __x to the exponent \a __y.
  */
extern double pow(double __x, double __y) __ATTR_CONST__;

  /**
     \ingroup avr_math

     The function isnan() returns 1 if the argument \a __x represents a
     "not-a-number" (NaN) object, otherwise 0.
  */
extern int isnan(double __x) __ATTR_CONST__;

  /**
     \ingroup avr_math

     The function isinf() returns 1 if the argument \a __x is positive
     infinity, -1 if \a __x is negative infinity, and 0 otherwise.
  */
extern int isinf(double __x) __ATTR_CONST__;

  /**
     \ingroup avr_math

     The function square() returns <em>__x * __x</em>.

     \note
     This function does not belong to the C standard definition.
  */
extern double square(double __x) __ATTR_CONST__;

  /**
     \ingroup avr_math

     The copysign() function returns \a __x but with the sign of \a __y.
     They work even if \a __x or \a __y are NaN or zero.
 */
__ATTR_CONST__ extern inline double copysign (double __x, double __y)
{
    asm (
	"bst	%D2, 7	\n\t"
	"bld	%D0, 7	"
	: "=r" (__x)
	: "0" (__x), "r" (__y) );
    return __x;
}

  /**
     \ingroup avr_math

     The fdim() function returns <em>max(__x - __y, 0)</em>. If \a __x or
     \a __y or both are NaN, NaN is returned.
  */
extern double fdim (double __x, double __y) __ATTR_CONST__;

  /**
     \ingroup avr_math

     The fma() function performs floating-point multiply-add. This is the
     operation <em>(__x * __y) + __z</em>, but the intermediate result is
     not rounded to the destination type.  This can sometimes improve the
     precision of a calculation.
  */
extern double fma (double __x, double __y, double __z) __ATTR_CONST__;

  /**
     \ingroup avr_math

     The fmax() function returns the greater of the two values \a __x and
     \a __y. If an argument is NaN, the other argument is returned. If
     both arguments are NaN, NaN is returned.
  */
extern double fmax (double __x, double __y) __ATTR_CONST__;

  /**
     \ingroup avr_math

     The fmin() function returns the lesser of the two values \a __x and
     \a __y. If an argument is NaN, the other argument is returned. If
     both arguments are NaN, NaN is returned.
  */
extern double fmin (double __x, double __y) __ATTR_CONST__;

  /**
     \ingroup avr_math

     The signbit() function returns a nonzero value if the value of \a __x
     has its sign bit set.  This is not the same as `\a __x < 0.0',
     because IEEE 754 floating point allows zero to be signed. The
     comparison `-0.0 < 0.0' is false, but `signbit (-0.0)' will return a
     nonzero value.
     
     \note
     This implementation returns 1 if sign bit is set.
  */
extern int signbit (double __x) __ATTR_CONST__;

  /**
     \ingroup avr_math

     The trunc() function rounds \a __x to the nearest integer not larger
     in absolute value.
  */
extern double trunc (double __x) __ATTR_CONST__;

  /**
     \ingroup avr_math

     The isfinite() function returns a nonzero value if \a __x is finite:
     not plus or minus infinity, and not NaN.
  */
__ATTR_CONST__ extern inline int isfinite (double __x)
{
    unsigned char __exp;
    asm (
	"mov	%0, %C1		\n\t"
	"lsl	%0		\n\t"
	"mov	%0, %D1		\n\t"
	"rol	%0		"
	: "=r" (__exp)
	: "r" (__x)	);
    return __exp != 0xff;
}

  /**
     \ingroup avr_math

     The hypot() function returns <em>sqrt(__x*__x + __y*__y)</em>. This
     is the length of the hypotenuse of a right triangle with sides of
     length \a __x and \a __y, or the  distance of the point (\a __x, \a
     __y) from the origin. Using this function  instead of the direct
     formula is wise, since the error is much smaller. No underflow with
     small \a __x and \a __y. No overflow if result is in range.
  */
double hypot (double __x, double __y) __ATTR_CONST__;

/** \ingroup avr_math

    The round() function rounds \a __x to the nearest integer, but rounds
    halfway cases away from zero (instead of to the nearest even integer).
    Overflow is impossible.

    \return The rounded value. If \a __x is an integral or infinite, \a
    __x itself is returned. If \a __x is \c NaN, then \c NaN is returned.
 */
double round (double __x) __ATTR_CONST__;

/** \ingroup avr_math

    The lround() function rounds \a __x to the nearest integer, but rounds
    halfway cases away from zero (instead of to the nearest even integer).
    This function is similar to round() function, but it differs in type of
    return value and in that an overflow is possible.

    \return The rounded long integer value. If \a __x is not a finite number
    or an overflow was, this realization returns the \c LONG_MIN value
    (0x80000000).
 */
long lround (double __x) __ATTR_CONST__;

/** \ingroup avr_math

    The lrint() function rounds \a __x to the nearest integer, rounding the
    halfway cases to the even integer direction. (That is both 1.5 and 2.5
    values are rounded to 2). This function is similar to rint() function,
    but it differs in type of return value and in that an overflow is
    possible.

    \return The rounded long integer value. If \a __x is not a finite
    number or an overflow was, this realization returns the \c LONG_MIN
    value (0x80000000).
 */
long lrint (double __x) __ATTR_CONST__;

#ifdef __cplusplus
}
#endif

#endif /* _MATH_H */

