mpz/fib2_ui.c: Use tabulated values, when available.

1 files changed, 13 insertions, 4 deletions

diff --git a/mpz/fib2_ui.c b/mpz/fib2_ui.c
index 122db8dd5..ddf456f58 100644
--- a/mpz/fib2_ui.c
+++ b/mpz/fib2_ui.c
@@ -1,6 +1,6 @@
 /* mpz_fib2_ui -- calculate Fibonacci numbers.
 
-Copyright 2001, 2012 Free Software Foundation, Inc.
+Copyright 2001, 2012, 2014 Free Software Foundation, Inc.
 
 This file is part of the GNU MP Library.
 
@@ -39,12 +39,21 @@ 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)
+    {
+      PTR(fn)[0] = FIB_TABLE (n);
+      SIZ(fn) = (n != 0);      /* F[0]==0, others are !=0 */
+      PTR(fnsub1)[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_REALLOC (fn,     size);
-  f1p = MPZ_REALLOC (fnsub1, size);
+  fp =  MPZ_NEWALLOC (fn,     size);
+  f1p = MPZ_NEWALLOC (fnsub1, size);
 
   size = mpn_fib2_ui (fp, f1p, n);
 
-  SIZ(fn)     = size - (n == 0);
+  SIZ(fn)     = size;
   SIZ(fnsub1) = size - (f1p[size-1] == 0);
 }