Imported gcc-4.4.3

[msp430-gcc.git] / gmp / mpn / generic / random2.c

diff --git a/gmp/mpn/generic/random2.c b/gmp/mpn/generic/random2.c
new file mode 100644 (file)
index 0000000..e29238c
--- /dev/null
+++ b/gmp/mpn/generic/random2.c
@@ -0,0 +1,96 @@
+/* mpn_random2 -- Generate random numbers with relatively long strings
+   of ones and zeroes.  Suitable for border testing.
+
+Copyright 1992, 1993, 1994, 1996, 2000, 2001, 2002, 2004 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"
+
+static void gmp_rrandomb __GMP_PROTO ((mp_ptr, gmp_randstate_t, unsigned long int));
+
+/* Ask _gmp_rand for 32 bits per call unless that's more than a limb can hold.
+   Thus, we get the same random number sequence in the common cases.
+   FIXME: We should always generate the same random number sequence!  */
+#if GMP_NUMB_BITS < 32
+#define BITS_PER_RANDCALL GMP_NUMB_BITS
+#else
+#define BITS_PER_RANDCALL 32
+#endif
+
+void
+mpn_random2 (mp_ptr rp, mp_size_t n)
+{
+  gmp_randstate_ptr rstate = RANDS;
+  int bit_pos;                 /* bit number of least significant bit where
+                                  next bit field to be inserted */
+  mp_limb_t ran, ranm;         /* buffer for random bits */
+
+  /* FIXME: Is n==0 supposed to be allowed? */
+  ASSERT (n >= 0);
+
+  _gmp_rand (&ranm, rstate, BITS_PER_RANDCALL);
+  ran = ranm;
+
+  /* Start off at a random bit position in the most significant limb.  */
+  bit_pos = ran % GMP_NUMB_BITS;
+
+  gmp_rrandomb (rp, rstate, n * GMP_NUMB_BITS - bit_pos);
+}
+
+static void
+gmp_rrandomb (mp_ptr rp, gmp_randstate_t rstate, unsigned long int nbits)
+{
+  unsigned long int bi;
+  mp_limb_t ranm;              /* buffer for random bits */
+  unsigned cap_chunksize, chunksize;
+  mp_size_t i;
+
+  /* Set entire result to 111..1  */
+  i = (nbits + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS - 1;
+  rp[i] = GMP_NUMB_MAX >> (GMP_NUMB_BITS - (nbits % GMP_NUMB_BITS)) % GMP_NUMB_BITS;
+  for (i = i - 1; i >= 0; i--)
+    rp[i] = GMP_NUMB_MAX;
+
+  _gmp_rand (&ranm, rstate, BITS_PER_RANDCALL);
+  cap_chunksize = nbits / (ranm % 4 + 1);
+  cap_chunksize += cap_chunksize == 0; /* make it at least 1 */
+
+  bi = nbits;
+
+  for (;;)
+    {
+      _gmp_rand (&ranm, rstate, BITS_PER_RANDCALL);
+      chunksize = 1 + ranm % cap_chunksize;
+      bi = (bi < chunksize) ? 0 : bi - chunksize;
+
+      if (bi == 0)
+       break;                  /* low chunk is ...1 */
+
+      rp[bi / GMP_NUMB_BITS] ^= CNST_LIMB (1) << bi % GMP_NUMB_BITS;
+
+      _gmp_rand (&ranm, rstate, BITS_PER_RANDCALL);
+      chunksize = 1 + ranm % cap_chunksize;
+      bi = (bi < chunksize) ? 0 : bi - chunksize;
+
+      mpn_incr_u (rp + bi / GMP_NUMB_BITS, CNST_LIMB (1) << bi % GMP_NUMB_BITS);
+
+      if (bi == 0)
+       break;                  /* low chunk is ...0 */
+    }
+}