Add Chromium-only Blender WebEngine parity work

blender-5.2.0/extern/gmp-source/mpf/pow_ui.c

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+/* mpf_pow_ui -- Compute b^e.
+
+Copyright 1998, 1999, 2001, 2012, 2015 Free Software Foundation, Inc.
+
+This file is part of the GNU MP Library.
+
+The GNU MP Library is free software; you can redistribute it and/or modify
+it under the terms of either:
+
+  * the GNU Lesser General Public License as published by the Free
+    Software Foundation; either version 3 of the License, or (at your
+    option) any later version.
+
+or
+
+  * the GNU General Public License as published by the Free Software
+    Foundation; either version 2 of the License, or (at your option) any
+    later version.
+
+or both in parallel, as here.
+
+The GNU MP 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 General Public License
+for more details.
+
+You should have received copies of the GNU General Public License and the
+GNU Lesser General Public License along with the GNU MP Library.  If not,
+see https://www.gnu.org/licenses/.  */
+
+#include "gmp-impl.h"
+#include "longlong.h"
+
+/* This uses a plain right-to-left square-and-multiply algorithm.
+
+   FIXME: When popcount(e) is not too small, it would probably speed things up
+   to use a k-ary sliding window algorithm.  */
+
+void
+mpf_pow_ui (mpf_ptr r, mpf_srcptr b, unsigned long int e)
+{
+  mpf_t t;
+  int cnt;
+
+  if (e <= 1)
+    {
+      if (e == 0)
+	mpf_set_ui (r, 1);
+      else
+	mpf_set (r, b);
+      return;
+    }
+
+  count_leading_zeros (cnt, (mp_limb_t) e);
+  cnt = GMP_LIMB_BITS - 1 - cnt;
+
+  /* Increase computation precision as a function of the exponent.  Adding
+     log2(popcount(e) + log2(e)) bits should be sufficient, but we add log2(e),
+     i.e. much more.  With mpf's rounding of precision to whole limbs, this
+     will be excessive only when limbs are artificially small.  */
+  mpf_init2 (t, mpf_get_prec (r) + cnt);
+
+  mpf_set (t, b);		/* consume most significant bit */
+  while (--cnt > 0)
+    {
+      mpf_mul (t, t, t);
+      if ((e >> cnt) & 1)
+	mpf_mul (t, t, b);
+    }
+
+  /* Do the last iteration specially in order to save a copy operation.  */
+  if (e & 1)
+    {
+      mpf_mul (t, t, t);
+      mpf_mul (r, t, b);
+    }
+  else
+    {
+      mpf_mul (r, t, t);
+    }
+
+  mpf_clear (t);
+}