Old Wang's TFT1P7148 4 x 3.2-inch LCD TVs

This is a very old screen, only supporting 9-bit 3-line SPI and RGB. Related links:
3.2-inch screen for 4.6 yuan_ESP32C3 driver board - JLCPCB EDA open source hardware platform (oshwhub.com);
Lao Wang TFT1P7148_SPI3_RGB_TFT - JLCPCB EDA open source hardware platform (oshwhub.com).
 
The experts provided software simulation and 16-bit SPI, simulating 9-bit SPI each time the CS is pulled to drive this screen, but frankly, the speed isn't ideal. Based on the 16-bit simulating 9-bit transmission, it's known that missing bits will become invalid after the CS is pulled. Therefore, I tried something similar to 9488, pre-processing the data to be sent, padding each byte with 1s and rearranging them, padding missing bits with 0s, and then sending it using 8-bit transmission. The refresh effect is still good, but unfortunately, my screen seems to be aging with severe color distortion.
 
The demo is based on the rt-thread device framework, with many inheritances and a somewhat messy layout; just look at the algorithm.