OpenXM_contrib/gmp/mpz/rrandomb.c - diff

Return to rrandomb.c CVS log

Up to [local] / OpenXM_contrib / gmp / mpz

Diff for /OpenXM_contrib/gmp/mpz/Attic/rrandomb.c between version 1.1.1.1 and 1.1.1.2

version 1.1.1.1, 2000/09/09 14:12:56

version 1.1.1.2, 2003/08/25 16:06:33

Line 2

long runs of consecutive ones and zeros in the binary representation.

Meant for testing of other MP routines.

This file is part of the GNU MP Library.

Line 27 MA 02111-1307, USA. */

static void gmp_rrandomb _PROTO ((mp_ptr rp, gmp_randstate_t rstate, unsigned long int nbits));

void

#if __STDC__

mpz_rrandomb (mpz_ptr x, gmp_randstate_t rstate, unsigned long int nbits)

#else

mpz_rrandomb (x, rstate, nbits)

mpz_ptr x;

gmp_randstate_t rstate;

unsigned long int nbits;

#endif

{

mp_size_t nl = 0;

if (nbits != 0)

{

mp_ptr xp;

nl = (nbits + BITS_PER_MP_LIMB - 1) / BITS_PER_MP_LIMB;

nl = (nbits + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS;

if (x->_mp_alloc < nl)

MPZ_REALLOC (x, nl);

_mpz_realloc (x, nl);

xp = PTR(x);

gmp_rrandomb (xp, rstate, nbits);

Line 53 mpz_rrandomb (x, rstate, nbits)

Line 45 mpz_rrandomb (x, rstate, nbits)

SIZ(x) = nl;

}

#define BITS_PER_CHUNK 4

/* It's a bit tricky to get this right, so please test the code well if you

hack with it. Some early versions of the function produced random numbers

with the leading limb == 0, and some versions never made the most

significant bit set.

static void

This code and mpn_random2 are almost identical, though the latter makes bit

#if __STDC__

runs of 1 to 32, and forces the first block to contain 1-bits.

gmp_rrandomb (mp_ptr rp, gmp_randstate_t rstate, unsigned long int nbits)

The random state produces some number of random bits per underlying lc

invocation (BITS_PER_RANDCALL). We should perhaps ask for that, instead of

asking for 32, 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. We 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

gmp_rrandomb (rp, rstate, nbits)

#define BITS_PER_RANDCALL 32

mp_ptr rp;

gmp_randstate_t rstate;

unsigned long int nbits;

#endif

static void

gmp_rrandomb (mp_ptr rp, gmp_randstate_t rstate, unsigned long int nbits)

{

int nb;

int bit_pos;

int bit_pos; /* bit number of least significant bit where

mp_size_t limb_pos;

next bit field to be inserted */

mp_limb_t ran, ranm;

mp_size_t ri; /* index in rp */

mp_limb_t acc;

mp_limb_t ran, ranm; /* buffer for random bits */

mp_size_t n;

mp_limb_t acc; /* accumulate output random data here */

int ran_nbits; /* number of valid bits in ran */

bit_pos = nbits % BITS_PER_MP_LIMB;

ran_nbits = 0;

limb_pos = nbits / BITS_PER_MP_LIMB;

bit_pos = (nbits - 1) % GMP_NUMB_BITS;

if (bit_pos == 0)

ri = (nbits - 1) / GMP_NUMB_BITS;

{

bit_pos = BITS_PER_MP_LIMB;

limb_pos--;

}

acc = 0;

while (limb_pos >= 0)

while (ri >= 0)

{

_gmp_rand (&ranm, rstate, BITS_PER_CHUNK + 1);

if (ran_nbits < LOGBITS_PER_BLOCK + 1)

ran = ranm;

{

nb = (ran >> 1) + 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)

{

/* Generate a string of ones. */

/* Generate a string of nb ones. */

if (nb > bit_pos)

{

rp[limb_pos--] = acc | ((((mp_limb_t) 1) << bit_pos) - 1);

rp[ri--] = acc | (((mp_limb_t) 2 << bit_pos) - 1);

bit_pos += BITS_PER_MP_LIMB;

bit_pos += GMP_NUMB_BITS;

bit_pos -= nb;

acc = (~(mp_limb_t) 0) << bit_pos;

acc = ((~(mp_limb_t) 1) << bit_pos) & GMP_NUMB_MASK;

}

else

{

bit_pos -= nb;

acc |= ((((mp_limb_t) 1) << nb) - 1) << bit_pos;

acc |= (((mp_limb_t) 2 << nb) - 2) << bit_pos;

}

else

{

/* Generate a string of zeroes. */

/* Generate a string of nb zeroes. */

if (nb > bit_pos)

{

rp[limb_pos--] = acc;

rp[ri--] = acc;

acc = 0;

bit_pos += BITS_PER_MP_LIMB;

bit_pos += GMP_NUMB_BITS;

}

bit_pos -= nb;

}

ran_nbits -= LOGBITS_PER_BLOCK + 1;

ran >>= LOGBITS_PER_BLOCK + 1;

}

FreeBSD-CVSweb <freebsd-cvsweb@FreeBSD.org>