Add Chromium-only Blender WebEngine parity work

blender-5.2.0/extern/gmp-source/mpz/mfac_uiui.c

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+/* mpz_mfac_uiui(RESULT, N, M) -- Set RESULT to N!^(M) = N(N-M)(N-2M)...
+
+Contributed to the GNU project by Marco Bodrato.
+
+Copyright 2012, 2013, 2015, 2016 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"
+
+/*************************************************************/
+/* Section macros: common macros, for swing/fac/bin (&sieve) */
+/*************************************************************/
+
+#define FACTOR_LIST_STORE(P, PR, MAX_PR, VEC, I)		\
+  do {								\
+    if ((PR) > (MAX_PR)) {					\
+      (VEC)[(I)++] = (PR);					\
+      (PR) = (P);						\
+    } else							\
+      (PR) *= (P);						\
+  } while (0)
+
+/*********************************************************/
+/* Section oder factorials:                              */
+/*********************************************************/
+
+/* mpz_mfac_uiui (x, n, m) computes x = n!^(m) = n*(n-m)*(n-2m)*...   */
+
+void
+mpz_mfac_uiui (mpz_ptr x, unsigned long n, unsigned long m)
+{
+  ASSERT (n <= GMP_NUMB_MAX);
+  ASSERT (m != 0);
+
+  if ((n < 3) | (n - 3 < m - 1)) { /* (n < 3 || n - 1 <= m || m == 0) */
+    MPZ_NEWALLOC (x, 1)[0] = n + (n == 0);
+    SIZ (x) = 1;
+  } else { /* 0 < m < n - 1 < GMP_NUMB_MAX */
+    mp_limb_t g, sn;
+    mpz_t     t;
+
+    sn = n;
+    g = mpn_gcd_1 (&sn, 1, m);
+    if (g > 1) { n/=g; m/=g; }
+
+    if (m <= 2) { /* fac or 2fac */
+      if (m == 1) {
+	if (g > 2) {
+	  mpz_init (t);
+	  mpz_fac_ui (t, n);
+	  sn = n;
+	} else {
+	  if (g == 2)
+	    mpz_2fac_ui (x, n << 1);
+	  else
+	    mpz_fac_ui (x, n);
+	  return;
+	}
+      } else { /* m == 2 */
+	if (g > 1) {
+	  mpz_init (t);
+	  mpz_2fac_ui (t, n);
+	  sn = n / 2 + 1;
+	} else {
+	  mpz_2fac_ui (x, n);
+	  return;
+	}
+      }
+    } else { /* m >= 3, gcd(n,m) = 1 */
+      mp_limb_t *factors;
+      mp_limb_t prod, max_prod;
+      mp_size_t j;
+      TMP_DECL;
+
+      sn = n / m + 1;
+
+      j = 0;
+      prod = n;
+      n -= m;
+      max_prod = GMP_NUMB_MAX / n;
+
+      if (g > 1)
+	factors = MPZ_NEWALLOC (x, sn / log_n_max (n) + 2);
+      else {
+	TMP_MARK;
+	factors = TMP_ALLOC_LIMBS (sn / log_n_max (n) + 2);
+      }
+
+      for (; n > m; n -= m)
+	FACTOR_LIST_STORE (n, prod, max_prod, factors, j);
+
+      factors[j++] = n;
+      factors[j++] = prod;
+
+      if (g > 1) {
+	mpz_init (t);
+	mpz_prodlimbs (t, factors, j);
+      } else {
+	mpz_prodlimbs (x, factors, j);
+	TMP_FREE;
+	return;
+      }
+    }
+
+    {
+      mpz_t p;
+
+      mpz_init (p);
+      mpz_ui_pow_ui (p, g, sn); /* g^sn */
+      mpz_mul (x, p, t);
+      mpz_clear (p);
+      mpz_clear (t);
+    }
+  }
+}