How to control the generation of fixed points within a fixed period of 1ms and gradually generate points (waveforms) according to the progress of the period (time)？

I generated the code for the model using a C coder, and for real-time performance, I want to push it forward every 1ms. During this 1ms cycle, there are some other tasks that need to be completed in addition to the points that should be generated based on the step size. Therefore, I do not want to simply push the waveform generation based on the step size, as this will result in new points coming before I have finished reading and writing, which may miss or overwrite these points. This is something I do not want to happen.