PinyWings on Gossan

This release of Gossan incorporates several bug fixes and compatibility improvements on the Pebble API surface. Proudly, Gossan now ships with one additional game from the Rebble AppStore: PinyWings!

To allow PinyWings to run on Playdate, two more interesting capabilities had been added to Gossan. First, the ability to pre-seed Pebble's per-app storage. This can get us closer to the original experience of certain Pebble apps, especially without Internet connectivity. In the context of PinyWings, this is being used to disable the trial mode of the game and to unlock the full gaming experience as if the user had previously paid for the game (yes, this is OK – I consulted with the author of the game 😉).

Second, Gossan can now apply patches to the ARM binary when loading PBWs. In the case of PinyWings, this is relevant since the game does some nasty things to the execution stack provided by the Pebble runtime. Gossan's memory layout for the stack is different enough for PinyWings to crash as-is. It turned out that the easiest path was to replace 6 specific bytes in the binary so Gossan now has the ability to perform app-specific patches on load. Patching binaries at runtime will become handy for other apps in the future as well…