ATiny45 C Code for measuring gas resistance of a BME 680 while setting different temperatures

Hi! I have a schematic (see picture) where I connect a BME680 with a ATtiny45 (in the schematic is written tiny13, but it is 45) and a LED (and a buzzer, which is not matter of this project). I need a code which is small enough to be written to the little Flash of the ATtiny45 where the temperature of the gassensor can be set with a function [login to view URL] (uint16_t heaterTemp, uint16_t heaterTime) and a function [login to view URL]() which reads the resistance of the gassensor in the BME680. The LED should turn on when the gasresistance drops unter 300k while the temperature switches from 450°C (for 1 second) to 250°C (for 5 seconds). The code should be in C.