Sleephack is a small modification of Dwedit's sleep tool patcher. Dwedit's tool was originally created to patch in sleep support, through a hot key, into any GBA as there are many GBA games without built-in sleep support. Meanwhile, those with an EZ-Flash IV cartridge are likely to notice that sleep mode doesn't work at all in many games, due to a bug in the EZ-Flash IV, and homebrew software is unlikely to be compatible with EZ-Flash IV's soft reset patching method, as the EZ-Flash IV client seems to use a database of addresses for soft reset patching purposes. As I result, I changed Dwedit's tool, which works by patching in a keypad interrupt routine, to work around the EZ-Flash IV bug and add a more generically available soft reset function.
For a patched game/homebrew, use L+R+Start to sleep, Select+Start to wake, and L+R+Start+Select to soft reset on an EZ-Flash IV.
To patch a GBA game/homebrew:
If successful, you should see at least one group of lines similar to:
Even if such a group of lines are discovered, there is still the possibility of quirks or other issues that make result in malfunction of the game. This can include things like: not all interrupt hook handlers being discovered, since not all interrupt hook handlers can be automatically discovered, which may mean sleephack's interrupt hook may be overriden; sleephack's interrupt hook causing buzzing or crashing as the extra time used by sleephack's keypad interrupt can cause timing issues in game/program logic; and multilink games may have timing issues for similar issues, as many multilink games seem very time sensitive. Having said this, sleephack does work on a good many games without issue. But like any automatic patching system, it is best to carefully make sure that the patched software actually functions properly.
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