The hot group buffer (formerly up to 50 KB BSS / heap) is removed. During prewarm, each group is now decompressed into a transient malloc that is freed immediately after its glyphs are extracted — only one group buffer and the page buffer coexist at a time. For getBitmap() cache misses (rare: only hit when a glyph wasn't covered by prewarm), the group is also decompressed transiently and freed after the single glyph is compacted into _hotGlyphBuf. Peak heap during prewarm is now: page buffer + one group buffer. Outside of prewarm, heap usage is only the page buffer itself. Works correctly for large future fonts (Vietnamese, CJK) regardless of group size, with no permanent allocation overhead. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
CrossPoint Reader ++
This firmware is based on the crosspoint-reader for the XTEINK X4, a great piece of software by Dave Allie and others
Why this fork
Unfortunately the official repository suffers from too many good ideas floating around and a lack of clear governance how to deal with these contributions, so it's lacking fundamental fixes for a proper reading experience (rendering issues, sub-par sync capabilities with KOReader, a popular multi-platform open-source epub reader).
Trying to contribute enhancements / fixes became increasingly difficult as the lack of progress effectively prevented further development.
Therefore this branch focuses on real fixes and real improvements while trying to keep up to pace with developments in the main branch.
What's different
- Proper KOReader Snychronisation (including https TLS OOM fix)
- Fixes for a lot of css rendering issues
- Additional sleep screens support (information overlay, transparent pictures over current reader screen)
- Clock-Support
- Weather information panel
- Multiple under-the-hood performance improvements
- Book information screen
- ...
Choosing the right reader...
Your usecase might be completely different from mine, so I try to give an overview of the different reader flavors to my best knowledge. If you know of more variants / have more information, then let me know
Last update: April, 12th, 2026
| Reader | Visual appeal | Functionality | Formats | Pros | Cons | Custom fonts | CJK | Bluetooth |
|---|---|---|---|---|---|---|---|---|
| Stock | Okay | Reader | XTC, EPUB, TXT | Frequent official updates | Lot of rendering issues | Yes | Yes | Yes |
| THIS FORK: CrossPoint ++ | Okay | Calibre Wireless support; Proper KOReader progress sync; Wi-Fi transfer; Book Info; Clock, Weather Info | EPUB, XTC, TXT | Faster integration of functionality | Small team | No | No | No |
| CrossPoint | Okay | Calibre Wireless support; Limited KOReader progress sync; Wi-Fi transfer | EPUB, XTC, TXT | Biggest community | Least common denominator approach | No | No | No |
| CrossPet | Excellent, Playful | Virtual pet motivator; mini-games | EPUB, TXT | A lot of additional apps | Higher battery drain, Small team, bloaty | Yes | Yes | Yes |
| Papyrix | Minimalist | Calibre Wireless support; exFAT support | EPUB, FB2, MD, TXT | A lot of good ideas | Small team | Yes | Yes | No |
| Inx | Nice | mainly crosspoint functionality plus reading statistics | EPUB, XTC, TXT | Good reading stats | Small team | No | No | No |
| vCodex | Nice | mainly crosspoint functionality plus reading statistics | EPUB, XTC, TXT | Good reading stats | Small team | No | No | No |
| PlusPoint | Okay | Experimental | EPUB, TXT, JS Apps | Support for custom JS apps; better RTC | Based on older code, small team | Yes | Yes | No |
| SUMI | Nice | Lua custom apps; Bluetooth keyboard support for notes; Game Boy emulator; Bluetooth Transfer | EPUB, TXT, Markdown, XTC | Many apps, customizable, Papyrix fork | Single Contributor, No Wi-Fi | Yes | Yes | Yes |