akr	2008-02-17 09:18:16 +0900 (Sun, 17 Feb 2008)

  New Revision: 15514

  Modified files:
    trunk/ChangeLog
    trunk/string.c
    trunk/test/ruby/test_string.rb

  Log:
    * string.c (rb_str_times): reduce loop overhead.


  http://svn.ruby-lang.org/cgi-bin/viewvc.cgi/trunk/test/ruby/test_string.rb?r1=15514&r2=15513&diff_format=u
  http://svn.ruby-lang.org/cgi-bin/viewvc.cgi/trunk/string.c?r1=15514&r2=15513&diff_format=u
  http://svn.ruby-lang.org/cgi-bin/viewvc.cgi/trunk/ChangeLog?r1=15514&r2=15513&diff_format=u

Index: ChangeLog
===================================================================
--- ChangeLog	(revision 15513)
+++ ChangeLog	(revision 15514)
@@ -1,3 +1,7 @@
+Sun Feb 17 09:17:08 2008  Tanaka Akira  <akr@f...>
+
+	* string.c (rb_str_times): reduce loop overhead.
+
 Sun Feb 17 03:37:01 2008  Tanaka Akira  <akr@f...>
 
 	* include/ruby/re.h (struct rmatch_offset): new struct for character
Index: string.c
===================================================================
--- string.c	(revision 15513)
+++ string.c	(revision 15514)
@@ -762,7 +762,7 @@
 rb_str_times(VALUE str, VALUE times)
 {
     VALUE str2;
-    long i, len;
+    long n, len;
 
     len = NUM2LONG(times);
     if (len < 0) {
@@ -773,9 +773,14 @@
     }
 
     str2 = rb_str_new5(str, 0, len *= RSTRING_LEN(str));
-    for (i = 0; i < len; i += RSTRING_LEN(str)) {
-	memcpy(RSTRING_PTR(str2) + i,
-	       RSTRING_PTR(str), RSTRING_LEN(str));
+    if (len) {
+        n = RSTRING_LEN(str);
+        memcpy(RSTRING_PTR(str2), RSTRING_PTR(str), n);
+        while (n <= len/2) {
+            memcpy(RSTRING_PTR(str2) + n, RSTRING_PTR(str2), n);
+            n *= 2;
+        }
+        memcpy(RSTRING_PTR(str2) + n, RSTRING_PTR(str2), len-n);
     }
     RSTRING_PTR(str2)[RSTRING_LEN(str2)] = '\0';
     OBJ_INFECT(str2, str);
Index: test/ruby/test_string.rb
===================================================================
--- test/ruby/test_string.rb	(revision 15513)
+++ test/ruby/test_string.rb	(revision 15514)
@@ -174,7 +174,7 @@
     s = "a"
     10.times {|i|
       s << s
-      assert_equal("a" * (2<<i), s)
+      assert_equal("a" * (2 << i), s)
     }
   end
 
@@ -1370,4 +1370,13 @@
   def test_end_with?
     assert("abc".end_with?("c"))
   end
+
+  def test_times
+    s1 = ''
+    100.times {|n|
+      s2 = "a" * n
+      assert_equal(s1, s2)
+      s1 << 'a'
+    }
+  end
 end

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