Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Keil/AT32F415xx_v2/SDIO1/BUF#0x0
bits 31:0 = FIFOData: Receive and transmit FIFO data
FIFOData
https://github.com/cmsis-svd/cmsis-svd-data