void mpz_lucnum2_ui (mpz_ptr ln, mpz_ptr lnsub1, unsigned long n) { mp_ptr lp, l1p, f1p; mp_size_t size; mp_limb_t c; TMP_DECL; ASSERT (ln != lnsub1); /* handle small n quickly, and hide the special case for L[-1]=-1 */ if (n <= FIB_TABLE_LUCNUM_LIMIT) { mp_limb_t f = FIB_TABLE (n); mp_limb_t f1 = FIB_TABLE ((int) n - 1); /* L[n] = F[n] + 2F[n-1] */ PTR(ln)[0] = f + 2*f1; SIZ(ln) = 1; /* L[n-1] = 2F[n] - F[n-1], but allow for L[-1]=-1 */ PTR(lnsub1)[0] = (n == 0 ? 1 : 2*f - f1); SIZ(lnsub1) = (n == 0 ? -1 : 1); return; } TMP_MARK; size = MPN_FIB2_SIZE (n); f1p = TMP_ALLOC_LIMBS (size); MPZ_REALLOC (ln, size+1); MPZ_REALLOC (lnsub1, size+1); lp = PTR(ln); l1p = PTR(lnsub1); size = mpn_fib2_ui (l1p, f1p, n); /* L[n] = F[n] + 2F[n-1] */ #if HAVE_NATIVE_mpn_addlsh1_n c = mpn_addlsh1_n (lp, l1p, f1p, size); #else c = mpn_lshift1 (lp, f1p, size); c += mpn_add_n (lp, lp, l1p, size); #endif lp[size] = c; SIZ(ln) = size + (c != 0); /* L[n-1] = 2F[n] - F[n-1] */ c = mpn_double (l1p, size); c -= mpn_sub_n (l1p, l1p, f1p, size); ASSERT ((mp_limb_signed_t) c >= 0); l1p[size] = c; SIZ(lnsub1) = size + (c != 0); TMP_FREE; }
void check_fib_table (void) { int i; for (i = 1; i <= FIB_TABLE_LIMIT; i++) ASSERT_ALWAYS (FIB_TABLE(i) != 0); }
void mpz_fib2_ui (mpz_ptr fn, mpz_ptr fnsub1, unsigned long n) { mp_ptr fp, f1p; mp_size_t size; if (n <= FIB_TABLE_LIMIT) { MPZ_NEWALLOC (fn, 1)[0] = FIB_TABLE (n); SIZ(fn) = (n != 0); /* F[0]==0, others are !=0 */ MPZ_NEWALLOC (fnsub1, 1)[0] = FIB_TABLE ((int) n - 1); SIZ(fnsub1) = (n != 1); /* F[1-1]==0, others are !=0 */ return; } size = MPN_FIB2_SIZE (n); fp = MPZ_NEWALLOC (fn, size); f1p = MPZ_NEWALLOC (fnsub1, size); size = mpn_fib2_ui (fp, f1p, n); SIZ(fn) = size; SIZ(fnsub1) = size - (f1p[size-1] == 0); }