Sorry if this question has been ask before, but I couldn't find an answer on either google or the forum search tool. I was wondering, is there a point in the GBA ROM that list the cut off point in the ROM like in the nDS ROM. I have made a nDS ROM trimmer but want to add a GBA function to it since I got a EZFlashV. If there isn't a mention of it, is there a method I could do to trim the ROMS? Thanks for the help.
Of course there is a way. Download this trimmer: http://techsuki.net/nintendo-ds-rom-trimmer/ It's for both NDS and GBA roms. It works superfast, give it a try.
To answer your question there is no rom size internal to the rom (it is why we had problems with overdumps* and underdumps). For most roms you will have to search back through the rom until you hit something other than 00 or FF (maybe alternating 00 - FF). Here some trimmers will just drop everything afterwards but some will add a byte or three as a safety (end of lines and the like have often been signalled with 00 or FF) and some other roms most notably Riviera: The Promised Land and Bleach (256Mbit roms) have something that is either junk, very crude anti piracy (having manually trimmed the rom several users have reported problems) or possibly actual game code (see previous bracketed text) following a large section of repeating 00 or FF. *overdumps will not be 00 or FF but will align to the boundaries (powers of two), some older trainers/intros, hacks and hacking tools will also place their code at the very end of the rom frustrating your efforts. If you are considering something "hacksafe" know that many hacks have and continue to use the upper 16 megabytes afforded by the GBA memory bus so a list may not be entirely effective. Speaking of lists underdumps and overdumps did fly below the radar fairly often (as an example an English language pokemon game took some time for the overdump news it to hit the scene proper and on the flip side if you are concerned with ROM sizes as in actual chips some of the new classics were technically underdumps but that will not cause play issues as everything fit into a fraction of the chip size).
You should not use this info for deciding where to trim a DS rom. Other trimmers have used this method in the past, and they broke download play on nearly every rom they trimmed (this is why all the rom trimmers had to be updated once flashcarts started supporting DL play). There are also some games that do not have their size listed, and these roms either cause an error or output a zero byte file.
