Adds HAL-level support for the Xteink X3 (SSD1677 controller, 792x528
display). Includes device detection, display initialization, button
mapping, power management, and theme adjustments for the X3 form factor.
gpio_hold_en(GPIO13) called in startDeepSleep() persists after wake when
keepClockAlive=true. A subsequent startDeepSleep() call (e.g. failed button
verification) would silently fail to change GPIO13's level, leaving the MOSFET
latched and trapping the device in a sleep/wake loop requiring a hardware reset.
Release the individual and global holds at the top of startDeepSleep() so each
sleep entry configures GPIO13 from a clean state. Also call
gpio_deep_sleep_hold_dis() immediately after wake in setup() as a defensive
measure.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
## Summary
Replace per-pixel getRenderMode() + rotateCoordinates() + bounds checks
with a DirectPixelWriter struct that pre-computes orientation and render
mode state once per row. Use bitwise ops instead of division/modulo for
cache pixel packing. Skip PNG cache allocation when buffer exceeds 48KB
(framebuffer size) since PNG decode is fast enough that caching provides
minimal benefit, and the large buffer competes with the 44KB PNG decoder
for heap.
## Additional Context
Measured improvements on ESP32-C3 @ 160MHz:
- JPEG decode: 5-7% faster (1:1 scale)
- PNG decode: 15-20% faster (1:1 scale)
- Cache renders: 3-6% faster across both formats
- Eliminates "Failed to allocate cache buffer" errors for large PNGs
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### AI Usage
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Did you use AI tools to help write this code? _**< PARTIALLY >**_
jpirnay