void field_init_tiny_fp(field_ptr f, mpz_t prime) {
pbc_mpui *p;
PBC_ASSERT(mpz_fits_ulong_p(prime), "modulus too big");
field_init(f);
f->init = fp_init;
f->clear = fp_clear;
f->set_si = fp_set_si;
f->set_mpz = fp_set_mpz;
f->out_str = fp_out_str;
f->add = fp_add;
f->sub = fp_sub;
f->set = fp_set;
f->mul = fp_mul;
f->mul_si = fp_mul_si;
f->square = fp_square;
f->doub = fp_double;
f->pow_mpz = fp_pow_mpz;
f->neg = fp_neg;
f->cmp = fp_cmp;
f->sign = fp_sgn_odd;
f->invert = fp_invert;
f->random = fp_random;
f->from_hash = fp_from_hash;
f->is1 = fp_is1;
f->is0 = fp_is0;
f->set0 = fp_set0;
f->set1 = fp_set1;
f->is_sqr = fp_is_sqr;
f->sqrt = element_tonelli;
f->field_clear = fp_field_clear;
f->to_bytes = fp_to_bytes;
f->from_bytes = fp_from_bytes;
f->to_mpz = fp_to_mpz;
p = f->data = pbc_malloc(sizeof(pbc_mpui));
*p = mpz_get_ui(prime);
{
pbc_mpui l = 255;
f->fixed_length_in_bytes = 1;
while (l < *p) {
f->fixed_length_in_bytes++;
l <<= 8;
l += 255;
}
}
mpz_set(f->order, prime);
}
void field_init_fast_fp(field_ptr f, mpz_t prime) {
PBC_ASSERT(!mpz_fits_ulong_p(prime), "modulus too small");
fp_field_data_ptr p;
field_init(f);
f->init = fp_init;
f->clear = fp_clear;
f->set_si = fp_set_si;
f->set_mpz = fp_set_mpz;
f->out_str = fp_out_str;
f->add = fp_add;
f->sub = fp_sub;
f->set = fp_set;
f->mul = fp_mul;
f->mul_si = fp_mul_si;
f->square = fp_square;
f->doub = fp_double;
f->halve = fp_halve;
f->pow_mpz = fp_pow_mpz;
f->neg = fp_neg;
f->cmp = fp_cmp;
f->sign = mpz_odd_p(prime) ? fp_sgn_odd : fp_sgn_even;
f->invert = fp_invert;
f->random = fp_random;
f->from_hash = fp_from_hash;
f->is1 = fp_is1;
f->is0 = fp_is0;
f->set0 = fp_set0;
f->set1 = fp_set1;
f->is_sqr = fp_is_sqr;
f->sqrt = element_tonelli;
f->field_clear = fp_field_clear;
f->to_bytes = fp_to_bytes;
f->from_bytes = fp_from_bytes;
f->to_mpz = fp_to_mpz;
p = f->data = pbc_malloc(sizeof(fp_field_data_t));
p->limbs = mpz_size(prime);
p->bytes = p->limbs * sizeof(mp_limb_t);
p->primelimbs = pbc_malloc(p->bytes);
mpz_export(p->primelimbs, &p->limbs, -1, sizeof(mp_limb_t), 0, 0, prime);
mpz_set(f->order, prime);
f->fixed_length_in_bytes = (mpz_sizeinbase(prime, 2) + 7) / 8;
}
void field_init_mont_fp(field_ptr f, mpz_t prime) {
PBC_ASSERT(!mpz_fits_ulong_p(prime), "modulus too small");
fptr p;
field_init(f);
f->init = fp_init;
f->clear = fp_clear;
f->set_si = fp_set_si;
f->set_mpz = fp_set_mpz;
f->out_str = fp_out_str;
f->snprint = fp_snprint;
f->set_str = fp_set_str;
f->add = fp_add;
f->sub = fp_sub;
f->set = fp_set;
f->mul = fp_mul;
f->doub = fp_double;
f->halve = fp_halve;
f->pow_mpz = fp_pow_mpz;
f->neg = fp_neg;
f->sign = fp_sgn_odd;
f->cmp = fp_cmp;
f->invert = fp_invert;
f->random = fp_random;
f->from_hash = fp_from_hash;
f->is1 = fp_is1;
f->is0 = fp_is0;
f->set0 = fp_set0;
f->set1 = fp_set1;
f->is_sqr = fp_is_sqr;
f->sqrt = element_tonelli;
f->field_clear = fp_field_clear;
f->to_bytes = fp_to_bytes;
f->from_bytes = fp_from_bytes;
f->to_mpz = fp_to_mpz;
f->out_info = fp_out_info;
// Initialize per-field data specific to this implementation.
f->data = pbc_malloc(sizeof(*p));
p = (fptr)f->data;
p->limbs = mpz_size(prime);
p->bytes = p->limbs * sizeof(mp_limb_t);
p->primelimbs = (mp_limb_t*)pbc_malloc(p->bytes);
mpz_export(p->primelimbs, &p->limbs, -1, sizeof(mp_limb_t), 0, 0, prime);
mpz_set(f->order, prime);
f->fixed_length_in_bytes = (mpz_sizeinbase(prime, 2) + 7) / 8;
// Compute R, R3 and negpinv.
mpz_t z;
mpz_init(z);
p->R = (mp_limb_t*)pbc_malloc(p->bytes);
p->R3 = (mp_limb_t*)pbc_malloc(p->bytes);
mpz_setbit(z, p->bytes * 8);
mpz_mod(z, z, prime);
set_limbs(p->R, z, p->limbs);
mpz_powm_ui(z, z, 3, prime);
set_limbs(p->R3, z, p->limbs);
mpz_set_ui(z, 0);
// Algorithm II.5 in Blake, Seroussi and Smart is better but this suffices
// since we're only doing it once.
mpz_setbit(z, p->bytes * 8);
mpz_invert(z, prime, z);
#ifdef _MSC_VER // for VC++ compatibility
int tmp = mpz_get_ui(z);
p->negpinv = -tmp;
#else
p->negpinv = -mpz_get_ui(z);
#endif
mpz_clear(z);
}
