Import of the watch repository from Pebble

third_party/jerryscript/jerry-libm/fmod.c

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+/* Copyright 2016 Samsung Electronics Co., Ltd.
+ * Copyright 2016 University of Szeged
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * This file is based on work under the following copyright and permission
+ * notice:
+ *
+ *     Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ *     Developed at SunSoft, a Sun Microsystems, Inc. business.
+ *     Permission to use, copy, modify, and distribute this
+ *     software is freely granted, provided that this notice
+ *     is preserved.
+ *
+ *     @(#)e_fmod.c 1.3 95/01/18
+ */
+
+#include "jerry-libm-internal.h"
+
+/* fmod(x,y)
+ * Return x mod y in exact arithmetic
+ *
+ * Method: shift and subtract
+ */
+
+static const double Zero[] = { 0.0, -0.0, };
+
+#define one 1.0
+
+double
+fmod (double x, double y)
+{
+  int n, hx, hy, hz, ix, iy, sx, i;
+  unsigned lx, ly, lz;
+
+  hx = __HI (x); /* high word of x */
+  lx = __LO (x); /* low  word of x */
+  hy = __HI (y); /* high word of y */
+  ly = __LO (y); /* low  word of 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)) /* |x| < |y| return x */
+    {
+      return x;
+    }
+    if (lx == ly) /* |x| = |y| return x * 0 */
+    {
+      return Zero[(unsigned) sx >> 31];
+    }
+  }
+
+  /* determine ix = ilogb(x) */
+  if (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 (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 (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 (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[(unsigned) 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[(unsigned) sx >> 31];
+  }
+  while (hx < 0x00100000) /* normalize x */
+  {
+    hx = hx + hx + (lx >> 31);
+    lx = lx + lx;
+    iy -= 1;
+  }
+  if (iy >= -1022) /* normalize output */
+  {
+    hx = ((hx - 0x00100000) | ((iy + 1023) << 20));
+    __HI (x) = hx | sx;
+    __LO (x) = lx;
+  }
+  else /* subnormal output */
+  {
+    n = -1022 - iy;
+    if (n <= 20)
+    {
+      lx = (lx >> n) | ((unsigned) hx << (32 - n));
+      hx >>= n;
+    }
+    else if (n <= 31)
+    {
+      lx = (hx << (32 - n)) | (lx >> n);
+      hx = sx;
+    }
+    else
+    {
+      lx = hx >> (n - 32);
+      hx = sx;
+    }
+    __HI (x) = hx | sx;
+    __LO (x) = lx;
+    x *= one; /* create necessary signal */
+  }
+  return x; /* exact output */
+} /* fmod */
+
+#undef one