Julia
b692bad10d
## Summary **What is the goal of this PR?** Restore compatibility with older XTC files that use the legacy 48-byte header layout, so they open correctly instead of failing header/page-table validation. **What changes are included?** - Updates the XTC parser to accept legacy files where pageTableOffset starts at 0x30 instead of the newer full header size. - Avoids treating legacy header bytes as a valid chapterOffset, so older files are not misclassified as having chapters. - Switches XTC file size and seek operations to 64-bit-safe wrapper calls in HalStorage, which matches the XTC format’s 64-bit offset fields and keeps page/chapter lookups from narrowing offsets. - Keeps the existing bounds checks and improves related logging when XTC page loads fail. ## Additional Context - This is a narrow compatibility fix for XTC handling. The functional change is in the XTC parser; the HalStorage changes are supporting wrapper methods needed by that parser update. - Risk should be low outside XTC reading, since the HAL changes only expose existing underlying file APIs rather than changing storage behavior. --- ### AI Usage While CrossPoint doesn't have restrictions on AI tools in contributing, please be transparent about their usage as it helps set the right context for reviewers. Did you use AI tools to help write this code? **YES**
# XTC/XTCH Library XTC ebook format support for CrossPoint Reader. ## Supported Formats | Format | Extension | Description | |--------|-----------|----------------------------------------------| | XTC | `.xtc` | Container with XTG pages (1-bit monochrome) | | XTCH | `.xtch` | Container with XTH pages (2-bit grayscale) | ## Format Overview XTC/XTCH are container formats designed for ESP32 e-paper displays. They store pre-rendered bitmap pages optimized for the XTeink X4 e-reader (480x800 resolution). ### Container Structure (XTC/XTCH) - 56-byte header with metadata offsets - Optional metadata (title, author, etc.) - Page index table (16 bytes per page) - Page data (XTG or XTH format) ### Page Formats #### XTG (1-bit monochrome) - Row-major storage, 8 pixels per byte - MSB first (bit 7 = leftmost pixel) - 0 = Black, 1 = White #### XTH (2-bit grayscale) - Two bit planes stored sequentially - Column-major order (right to left) - 8 vertical pixels per byte - Grayscale: 0=White, 1=Dark Grey, 2=Light Grey, 3=Black ## Reference Original format info: <https://gist.github.com/CrazyCoder/b125f26d6987c0620058249f59f1327d>