* bignum.c (bary_mul_precheck): Use bary_small_lshift or

bary_mul_normal if xl is 1.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41955 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,8 @@
+Sun Jul 14 00:14:15 2013  Tanaka Akira  <akr@fsij.org>
+
+	* bignum.c (bary_mul_precheck): Use bary_small_lshift or
+	  bary_mul_normal if xl is 1.
+
 Sat Jul 13 22:58:16 2013  Tanaka Akira  <akr@fsij.org>
 
 	* bignum.c (big_shift3): New function.

bignum.c

@@ -1903,14 +1903,23 @@ bary_mul_precheck(BDIGIT **zdsp, size_t *zlp, BDIGIT **xdsp, size_t *xlp, BDIGIT
         return 1;
     }
 
-    if (xl == 1 && xds[0] == 1) {
-        MEMCPY(zds, yds, BDIGIT, yl);
-        MEMZERO(zds + yl, BDIGIT, zl - yl);
-        return 1;
-    }
-    if (yl == 1 && yds[0] == 1) {
-        MEMCPY(zds, xds, BDIGIT, xl);
-        MEMZERO(zds + xl, BDIGIT, zl - xl);
+    if (xl == 1) {
+        if (xds[0] == 1) {
+            MEMCPY(zds, yds, BDIGIT, yl);
+            MEMZERO(zds+yl, BDIGIT, zl-yl);
+            return 1;
+        }
+        if (POW2_P(xds[0])) {
+            zds[yl] = bary_small_lshift(zds, yds, yl, bitsize(xds[0])-1);
+            MEMZERO(zds+yl+1, BDIGIT, zl-yl-1);
+            return 1;
+        }
+        if (yl == 1 && yds[0] == 1) {
+            zds[0] = xds[0];
+            MEMZERO(zds+1, BDIGIT, zl-1);
+            return 1;
+        }
+        bary_mul_normal(zds, zl, xds, xl, yds, yl);
         return 1;
     }