Member functions in structures in C51 Keil?

Question

Microcontrollers

I am writing a program for STM32 microcontrollers. I would like to use member functions in structures so that data and functions related to the same peripheral can be combined into one bundle. But in Keil mVision 5, the C51 compiler is used for compilation. In pure C, structures do not have member functions, respectively, and C51 swears at an attempt to declare a function as a member of a structure.
It seems that somewhere on the Keil website I met what it is in C51 that can be cranked, though now I can’t find where.
Does anyone know if this is really possible? Or is there another way?