Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32f1/STM32F101/CAN1/RF0R#0x0
receive FIFO 0 register
FMP0
FULL0
FOVR0
RFOM0
https://github.com/modm-io/cmsis-svd-stm32