ArduCopter Push() function - PWM output to ESC

i have read the code review at the ardupilot website and i saw at the diagram that the final function that suppose to send the pwm output to the ESC is : AP_HAL:RCoutput.cpp and it should be inside the push() function that is inside the function in this way:
void SRV_Channels::push()
i am trying to enter the push(); function to see how exactly it sends the PWM output to the ESC but i can’t find it. could anyone help me figure out how is the PWM output is sent to the ESC with the push() function?