301 Redirects for moving from mydomain.com/oldblog to blog.mydomain.com

I moved my blog from mydomain.com/oldblog to blog.mydomain.com I need to create 301 redirects from all of the old urls to the posts and pages to the new.

The permalink structure is the same. The only difference is mydomain.com/oldblog/post1 is now blog.mydomain.com/post1

I know I can do a 301 redirect within .htaccess which will automatically take a link like http://mydomain.com/oldblog/post1 and send it http://blog.mydomain.com/ but I need them all to match up! I cannot just have all old posts/pages pointing to the root URL of the new blog address.

Is there any automated tool to do this? I have about 850 blog posts/pages which need this and I cannot do this manually.

Thank you,

Chad