What did Charlie Sheen mean when he used the phrase "banging 7 gram rocks"?

Today’s Quote of Time.com ([email protected]) carries the following line of Charlie Sheen’s remark. Being totally ignorant of the background of CBS and Warner Brothers’ cancellation of the production of the program, I have no idea about the phrase, ‘bang 7 gram rock.’

I understand the line after ‘Because that’s how I roll ...’ means he is single-mindedly do what he decided to do – to sue CBC and Warner Broth. Can somebody translate the above line into English easier for a foreign learner like me to understand?

"I probably took more than anybody could survive. I was banging 7 gram rocks. Because that's how I roll. I have one speed. I have one gear: Go." CHARLIE SHEEN, who on Monday night, in addition to giving incoherent interviews, announced that he plans to sue CBS and Warner Brothers for canceling the production of Two and a Half Men.”

taking it a sentence at a time:

I probably took more than anybody could survive.

-> I did so many drugs I should have died [from an overdose].

I was banging 7 gram rocks

-> I was taking 7 grams of hard drugs [crack cocaine, probably] at a time.

That's how I roll.

-> That's the way I am.

I have one speed. I have one gear: Go.

-> I take chances, I take risks, I don't care about the negatives.

Banging 7-gram rocks.

He's talking about taking ("banging") crystals of crack cocaine. Seven grams is a LOT. According to the Wikipedia article, "Large amounts (several hundred milligrams or more) intensify the user's high, but may also lead to bizarre, erratic, and violent behavior." If a large dose is less than a gram, one wonders how Mr. Sheen survived at all.

That's how I roll.

Slang for "this is my normal, customary behavior."

I have one speed and one gear: go.

If he is moving at all, he is moving at his maximum speed.