Get the information stored in the Floating Point Data registers for the process associated with the file descriptor. The argument is a pointer to a procfs_fpreg structure (see debug_fpreg_t in <sys/debug.h>) that's filled in with the required information on return. If you provide a non-NULL extra argument, it's filled with the size of the data. For example:
procfs_fpreg my_fpreg; devctl( fd, DCMD_PROC_GETFPREG, my_fpreg, sizeof(procfs_fpreg), &size);
To set the Floating Point Data registers, use DCMD_PROC_SETFPREG .