hal_init - Sets up HAL and RTAPI
int hal_init(const char *modname)
The name of this hal module
hal_init sets up HAL and RTAPI. It must be called by any module that intends to use the API, before any other RTAPI calls.
modname must point to a string that identifies the module. The string may be no longer than HAL_NAME_LEN characters.
Call only from within user or init/cleanup code, not from relatime tasks.
On success, returns a positive integer module ID, which is used for subsequent calls to hal and rtapi APIs. On failure, returns a HAL error code.