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Diff for /OpenXM_contrib/gmp/mpn/generic/Attic/random2.c between version 1.1.1.2 and 1.1.1.3

version 1.1.1.2, 2000/09/09 14:12:27 version 1.1.1.3, 2003/08/25 16:06:20
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 /* mpn_random2 -- Generate random numbers with relatively long strings  /* mpn_random2 -- Generate random numbers with relatively long strings
    of ones and zeroes.  Suitable for border testing.     of ones and zeroes.  Suitable for border testing.
   
 Copyright (C) 1992, 1993, 1994, 1996, 2000 Free Software Foundation, Inc.  Copyright 1992, 1993, 1994, 1996, 2000, 2001, 2002 Free Software Foundation, Inc.
   
 This file is part of the GNU MP Library.  This file is part of the GNU MP Library.
   
Line 23  MA 02111-1307, USA. */
Line 23  MA 02111-1307, USA. */
 #include "gmp.h"  #include "gmp.h"
 #include "gmp-impl.h"  #include "gmp-impl.h"
   
 #if defined (__hpux) || defined (__alpha)  || defined (__svr4__) || defined (__SVR4)  
 /* HPUX lacks random().  DEC OSF/1 1.2 random() returns a double.  */  
 long mrand48 ();  
 static inline long  
 random ()  
 {  
   return mrand48 ();  
 }  
 #else  
 long random ();  
 #endif  
   
 /* It's a bit tricky to get this right, so please test the code well  /* It's a bit tricky to get this right, so please test the code well if you
    if you hack with it.  Some early versions of the function produced     hack with it.  Some early versions of the function produced random numbers
    random numbers with the leading limb == 0, and some versions never     with the leading limb == 0, and some versions never made the most
    made the most significant bit set.  */     significant bit set.
   
 void     This code and mpz_rrandomb are almost identical, though the latter makes bit
 #if __STDC__     runs of 1 to 16, and doesn't force the first block to contain 1-bits.
 mpn_random2 (mp_ptr res_ptr, mp_size_t size)  
      The RANDS random state currently produces 32 random bits per underlying lc
      invocation (BITS_PER_RANDCALL).  We therefore ask for that, presuming that
      limbs are at least 32 bits.  FIXME: Handle smaller limbs, such as 4-bit
      limbs useful for testing purposes, or limbs truncated by nailing.
   
      For efficiency, we make sure to use most bits returned from _gmp_rand, since
      the underlying random number generator is slow.  Keep returned bits in
      ranm/ran, and a count of how many bits remaining in ran_nbits.  */
   
   #define LOGBITS_PER_BLOCK 4
   
   /* 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  #else
 mpn_random2 (res_ptr, size)  #define BITS_PER_RANDCALL 32
      mp_ptr res_ptr;  
      mp_size_t size;  
 #endif  #endif
   
   void
   mpn_random2 (mp_ptr rp, mp_size_t n)
 {  {
   int n_bits;    gmp_randstate_ptr rstate = RANDS;
   int bit_pos;    int nb;
   mp_size_t limb_pos;    int bit_pos;                  /* bit number of least significant bit where
   unsigned int ran;                                     next bit field to be inserted */
   mp_limb_t limb;    mp_size_t ri;                 /* index in rp */
     mp_limb_t ran, ranm;          /* buffer for random bits */
     mp_limb_t acc;                /* accumulate output random data here */
     int ran_nbits;                /* number of valid bits in ran */
   
   limb = 0;    /* FIXME: Is n==0 supposed to be allowed? */
     ASSERT (n >= 0);
     ASSERT_ALWAYS (BITS_PER_MP_LIMB > LOGBITS_PER_BLOCK);
   
   /* Start off in a random bit position in the most significant limb.  */    _gmp_rand (&ranm, rstate, BITS_PER_RANDCALL);
   bit_pos = random () & (BITS_PER_MP_LIMB - 1);    ran = ranm;
   
   /* Least significant bit of RAN chooses string of ones/string of zeroes.    /* Start off at a random bit position in the most significant limb.  */
     bit_pos = ran % GMP_NUMB_BITS;
     ran >>= 6;                            /* Ideally   log2(GMP_NUMB_BITS) */
     ran_nbits = BITS_PER_RANDCALL - 6;    /* Ideally - log2(GMP_NUMB_BITS) */
   
     /* Bit 0 of ran chooses string of ones/string of zeroes.
      Make most significant limb be non-zero by setting bit 0 of RAN.  */       Make most significant limb be non-zero by setting bit 0 of RAN.  */
   ran = random () | 1;    ran |= 1;
   
   for (limb_pos = size - 1; limb_pos >= 0; )    ri = n - 1;
   
     acc = 0;
     while (ri >= 0)
     {      {
       n_bits = (ran >> 1) % BITS_PER_MP_LIMB + 1;        if (ran_nbits < LOGBITS_PER_BLOCK + 1)
           {
             _gmp_rand (&ranm, rstate, BITS_PER_RANDCALL);
             ran = ranm;
             ran_nbits = BITS_PER_RANDCALL;
           }
   
         nb = (ran >> 1) % (1 << LOGBITS_PER_BLOCK) + 1;
       if ((ran & 1) != 0)        if ((ran & 1) != 0)
         {          {
           /* Generate a string of ones.  */            /* Generate a string of nb ones.  */
           if (n_bits >= bit_pos)            if (nb > bit_pos)
             {              {
               res_ptr[limb_pos--] = limb | ((((mp_limb_t) 2) << bit_pos) - 1);                rp[ri--] = acc | (((mp_limb_t) 2 << bit_pos) - 1);
               bit_pos += BITS_PER_MP_LIMB;                bit_pos += GMP_NUMB_BITS;
               limb = (~(mp_limb_t) 0) << (bit_pos - n_bits);                bit_pos -= nb;
                 acc = ((~(mp_limb_t) 1) << bit_pos) & GMP_NUMB_MASK;
             }              }
           else            else
             {              {
               limb |= ((((mp_limb_t) 1) << n_bits) - 1) << (bit_pos - n_bits + 1);                bit_pos -= nb;
                 acc |= (((mp_limb_t) 2 << nb) - 2) << bit_pos;
             }              }
         }          }
       else        else
         {          {
           /* Generate a string of zeroes.  */            /* Generate a string of nb zeroes.  */
           if (n_bits >= bit_pos)            if (nb > bit_pos)
             {              {
               res_ptr[limb_pos--] = limb;                rp[ri--] = acc;
               limb = 0;                acc = 0;
               bit_pos += BITS_PER_MP_LIMB;                bit_pos += GMP_NUMB_BITS;
             }              }
             bit_pos -= nb;
         }          }
       bit_pos -= n_bits;        ran_nbits -= LOGBITS_PER_BLOCK + 1;
       ran = random ();        ran >>= LOGBITS_PER_BLOCK + 1;
     }      }
 }  }
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