Read value from a register (sub-register

Hello, I’m trying to read a sub-register but it seems like I don’t do the right way.
It’s the THR_64 that I’m trying to read.

When I read at the address given with the code below, I get values ​​that change while this value is supposed to be fixed.
uint32_t value = (dwt_read32bitoffsetreg(0x03,0x18)>> 9) & 0x3F;

Someone could help me please ?