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Justin Mitchell
83cd96bc2f
Adds a PlatformIO pre-build script to patch JPEGDEC library. When decoding progressive JPEGs with AC coefficients, MCU_SKIP (-8) causes array index 0xFFFFF8, creating a wild pointer ~33MB past the sMCUs array. The patch redirects pMCU to sMCUs[0] when MCU_SKIP is active, preventing store-access faults while maintaining correct behavior for JPEG_SCALE_EIGHTH decoding. Devices with larger framebuffers (like the x3) (792×528 = 52,272 bytes vs 800×480 = 48,000 bytes) have less free heap, shifting the allocation and changing where the wild pointer lands. Commit 8628297 guarded the DC coefficient write (pMCU[0]) with if (iMCU >= 0), which prevents crashes for progressive JPEGs whose first scan is DC-only (iScanEnd == 0). However, if the first scan includes AC coefficients (iScanEnd > 0), the AC decode loop still writes through the wild pointer and crashes.