Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32l1/STM32L100/SPI1/SR#0x0
status register
Receive buffer not empty
Transmit buffer empty
Channel side
Underrun flag
CRC error flag
Mode fault
Overrun flag
Busy flag
Frame Error
https://github.com/modm-io/cmsis-svd-stm32