ryokun6/crossmux

ryOS CrossMux is firmware, meaning the low level software that runs directly on the device, for the Xteink X3 and X4, a small e-ink e-reader gadget. It is a fork of an existing project called CrossMux, which itself builds on another firmware called CrossPoint Reader, and this particular fork is focused specifically on making the devices better for reading Chinese, Japanese, and Korean books. Older game and toy style apps that were part of the original firmware are not included in this reading focused version. The main addition is proper vertical text layout for EPUB books written in Chinese, Japanese, or Korean, since those languages are traditionally read top to bottom in columns running right to left, a layout most e-readers do not handle well. This fork's text engine lays out columns in that direction, correctly positions Chinese and Japanese punctuation marks according to standard typesetting conventions that differ between Traditional Chinese, Simplified Chinese, and Japanese, rotates any Latin text so it stays readable within vertical columns, and adjusts spacing and compression between characters the way professional CJK typesetting normally does. This vertical mode only turns on automatically for books whose file metadata marks them as Chinese, Japanese, or Korean, other books stay in a normal horizontal layout. The firmware ships in four separate localized builds, for Traditional Chinese, Simplified Chinese, Japanese, and Korean, each with its own translated interface and its own set of embedded CJK fonts so text renders correctly without needing extra files. The two Chinese builds can also automatically convert text between Traditional and Simplified characters on the fly, so the same book file can be opened correctly on either version. Other improvements in this fork include more reliable loading of custom fonts placed on the device's SD card, with fonts allowed in either of two folder locations and upcoming pages preloaded in advance, along with faster rendering of grayscale text using the e-ink display's four levels of gray. The README notes the current firmware version as 1.4.13.