# PIT API

In Shelter, the PIT is only used for one purpose: estimating the CPU frequency. It's only used with the PIC, never with the IOAPIC, so the API is volontarily very simple:
- `sh_pit_set_frequency()`: expect the frequency as argument. Set the PIT to uses this frequency and return nothing

This API is defined inside `shelter/lib/include/cpu/pit.h` and implemented inside `shelter/lib/include/cpu/pic.c`.