Imported gcc-4.4.3

[msp430-gcc.git] / gmp / mpz / urandomm.c

diff --git a/gmp/mpz/urandomm.c b/gmp/mpz/urandomm.c
new file mode 100644 (file)
index 0000000..b8a6d68
--- /dev/null
+++ b/gmp/mpz/urandomm.c
@@ -0,0 +1,94 @@
+/* mpz_urandomm (rop, state, n) -- Generate a uniform pseudorandom
+   integer in the range 0 to N-1, using STATE as the random state
+   previously initialized by a call to gmp_randinit().
+
+Copyright 2000, 2002  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 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.
+
+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 Lesser General Public
+License for more details.
+
+You should have received a copy of the GNU Lesser General Public License
+along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.  */
+
+#include "gmp.h"
+#include "gmp-impl.h"
+#include "longlong.h" /* for count_leading_zeros */
+
+
+#define MAX_URANDOMM_ITER  80
+
+void
+mpz_urandomm (mpz_ptr rop, gmp_randstate_t rstate, mpz_srcptr n)
+{
+  mp_ptr rp, np, nlast;
+  mp_size_t nbits, size;
+  int count;
+  int pow2;
+  int cmp;
+  TMP_DECL;
+
+  size = ABSIZ (n);
+  if (size == 0)
+    DIVIDE_BY_ZERO;
+
+  nlast = &PTR (n)[size - 1];
+
+  /* Detect whether n is a power of 2.  */
+  pow2 = POW2_P (*nlast);
+  if (pow2 != 0)
+    for (np = PTR (n); np < nlast; np++)
+      if (*np != 0)
+       {
+         pow2 = 0;             /* Mark n as `not a power of two'.  */
+         break;
+       }
+
+  count_leading_zeros (count, *nlast);
+  nbits = size * GMP_NUMB_BITS - (count - GMP_NAIL_BITS) - pow2;
+  if (nbits == 0)              /* nbits == 0 means that n was == 1.  */
+    {
+      SIZ (rop) = 0;
+      return;
+    }
+
+  TMP_MARK;
+  np = PTR (n);
+  if (rop == n)
+    {
+      mp_ptr tp;
+      tp = TMP_ALLOC_LIMBS (size);
+      MPN_COPY (tp, np, size);
+      np = tp;
+    }
+
+  /* Here the allocated size can be one too much if n is a power of
+     (2^GMP_NUMB_BITS) but it's convenient for using mpn_cmp below.  */
+  rp = MPZ_REALLOC (rop, size);
+  /* Clear last limb to prevent the case in which size is one too much.  */
+  rp[size - 1] = 0;
+
+  count = MAX_URANDOMM_ITER;   /* Set iteration count limit.  */
+  do
+    {
+      _gmp_rand (rp, rstate, nbits);
+      MPN_CMP (cmp, rp, np, size);
+    }
+  while (cmp >= 0 && --count != 0);
+
+  if (count == 0)
+    /* Too many iterations; return result mod n == result - n */
+    mpn_sub_n (rp, rp, np, size);
+
+  MPN_NORMALIZE (rp, size);
+  SIZ (rop) = size;
+  TMP_FREE;
+}