akr	2013-07-10 00:43:48 +0900 (Wed, 10 Jul 2013)

  New Revision: 41869

  http://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=rev&revision=41869

  Log:
    * bignum.c (bary_mul): x*1 is x.

  Modified files:
    trunk/ChangeLog
    trunk/bignum.c

Index: ChangeLog
===================================================================
--- ChangeLog	(revision 41868)
+++ ChangeLog	(revision 41869)
@@ -1,3 +1,7 @@ https://github.com/ruby/ruby/blob/trunk/ChangeLog#L1
+Wed Jul 10 00:41:42 2013  Tanaka Akira  <akr@f...>
+
+	* bignum.c (bary_mul): x*1 is x.
+
 Tue Jul  9 22:24:39 2013  Tanaka Akira  <akr@f...>
 
 	* bignum.c (bary_mul1): No need to invoke MEMZERO at last.
Index: bignum.c
===================================================================
--- bignum.c	(revision 41868)
+++ bignum.c	(revision 41869)
@@ -1856,6 +1856,17 @@ bary_mul(BDIGIT *zds, size_t zl, BDIGIT https://github.com/ruby/ruby/blob/trunk/bignum.c#L1856
         return;
     }
 
+    if (xl == 1 && xds[0] == 1) {
+        MEMCPY(zds, yds, BDIGIT, yl);
+        MEMZERO(zds + yl, BDIGIT, zl - yl);
+        return;
+    }
+    if (yl == 1 && yds[0] == 1) {
+        MEMCPY(zds, xds, BDIGIT, xl);
+        MEMZERO(zds + xl, BDIGIT, zl - xl);
+        return;
+    }
+
     /* normal multiplication when x is small */
     if (xl < KARATSUBA_MUL_DIGITS) {
       normal:

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