Dwedit posted this topic at the same time as a topic on Pocket Heaven about his thorough refactoring of PocketNES. So I would imagine that this topic relates to emulation on a GBA.
Bregalad wrote:
Armadillo I guess (makes non-standard uses of the scanline counter). Altough it's MMC3 it's not mapper 4 because of mirroring I guess.
It's TLSROM. But I'm not entirely sure how TLSROM would fit into the GBA's mirroring scheme, which ordinarily allows for 1-screen, vertical mirroring, horizontal mirroring, or 4-screen. Noticeably, TLSROM allows for diagonal mirroring ($2400=$2800, $2000=$2C00) or three-to-one-and-one-to-the-other mirroring (four possibilities), but the GBA doesn't.
(Aside: Thinking of all possible mirroring modes makes me want to play Lumines again...)