/*

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

 * 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.

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

 */

/*

 * __ieee754_fmod(x,y)

 * Return x mod y in exact arithmetic

 * Method: shift and subtract

 */

#include <math.h>

#include <math_private.h>

static const double one = 1.0, Zero[] = { 0.0, -0.0, };

double

__ieee754_fmod (double x, double y)

{

  int32_t n, hx, hy, hz, ix, iy, sx, i;

  uint32_t lx, ly, lz;

  EXTRACT_WORDS (hx, lx, x);

  EXTRACT_WORDS (hy, ly, y);

  sx = hx & 0x80000000;                 /* sign of x */

  hx ^= sx;                     /* |x| */

  hy &= 0x7fffffff;             /* |y| */

  /* purge off exception values */

  if ((hy | ly) == 0 || (hx >= 0x7ff00000) ||   /* y=0,or x not finite */

      ((hy | ((ly | -ly) >> 31)) > 0x7ff00000)) /* or y is NaN */

    return (x * y) / (x * y);

  if (hx <= hy)

    {

      if ((hx < hy) || (lx < ly))

	return x;                               /* |x|<|y| return x */

      if (lx == ly)

	return Zero[(uint32_t) sx >> 31];      /* |x|=|y| return x*0*/

    }

  /* determine ix = ilogb(x) */

  if (__glibc_unlikely (hx < 0x00100000))                  /* subnormal x */

    {

      if (hx == 0)

	{

	  for (ix = -1043, i = lx; i > 0; i <<= 1)

	    ix -= 1;

	}

      else

	{

	  for (ix = -1022, i = (hx << 11); i > 0; i <<= 1)

	    ix -= 1;

	}

    }

  else

    ix = (hx >> 20) - 1023;

  /* determine iy = ilogb(y) */

  if (__glibc_unlikely (hy < 0x00100000))                  /* subnormal y */

    {

      if (hy == 0)

	{

	  for (iy = -1043, i = ly; i > 0; i <<= 1)

	    iy -= 1;

	}

      else

	{

	  for (iy = -1022, i = (hy << 11); i > 0; i <<= 1)

	    iy -= 1;

	}

    }

  else

    iy = (hy >> 20) - 1023;

  /* set up {hx,lx}, {hy,ly} and align y to x */

  if (__glibc_likely (ix >= -1022))

    hx = 0x00100000 | (0x000fffff & hx);

  else                  /* subnormal x, shift x to normal */

    {

      n = -1022 - ix;

      if (n <= 31)

	{

	  hx = (hx << n) | (lx >> (32 - n));

	  lx <<= n;

	}

      else

	{

	  hx = lx << (n - 32);

	  lx = 0;

	}

    }

  if (__glibc_likely (iy >= -1022))

    hy = 0x00100000 | (0x000fffff & hy);

  else                  /* subnormal y, shift y to normal */

    {

      n = -1022 - iy;

      if (n <= 31)

	{

	  hy = (hy << n) | (ly >> (32 - n));

	  ly <<= n;

	}

      else

	{

	  hy = ly << (n - 32);

	  ly = 0;

	}

    }

  /* fix point fmod */

  n = ix - iy;

  while (n--)

    {

      hz = hx - hy; lz = lx - ly; if (lx < ly)

	hz -= 1;

      if (hz < 0)

	{

	  hx = hx + hx + (lx >> 31); lx = lx + lx;

	}

      else

	{

	  if ((hz | lz) == 0)           /* return sign(x)*0 */

	    return Zero[(uint32_t) sx >> 31];

	  hx = hz + hz + (lz >> 31); lx = lz + lz;

	}

    }

  hz = hx - hy; lz = lx - ly; if (lx < ly)

    hz -= 1;

  if (hz >= 0)

    {

      hx = hz; lx = lz;

    }

  /* convert back to floating value and restore the sign */

  if ((hx | lx) == 0)                   /* return sign(x)*0 */

    return Zero[(uint32_t) sx >> 31];

  while (hx < 0x00100000)               /* normalize x */

    {

      hx = hx + hx + (lx >> 31); lx = lx + lx;

      iy -= 1;

    }

  if (__glibc_likely (iy >= -1022))              /* normalize output */

    {

      hx = ((hx - 0x00100000) | ((iy + 1023) << 20));

      INSERT_WORDS (x, hx | sx, lx);

    }

  else                          /* subnormal output */

    {

      n = -1022 - iy;

      if (n <= 20)

	{

	  lx = (lx >> n) | ((uint32_t) hx << (32 - n));

	  hx >>= n;

	}

      else if (n <= 31)

	{

	  lx = (hx << (32 - n)) | (lx >> n); hx = sx;

	}

      else

	{

	  lx = hx >> (n - 32); hx = sx;

	}

      INSERT_WORDS (x, hx | sx, lx);

      x *= one;                 /* create necessary signal */

    }

  return x;                     /* exact output */

}

strong_alias (__ieee754_fmod, __fmod_finite)