Hi Shahzad

the code "as is" does not output anything

but to use it ,you would need to feed the output to the PCA set for 8bitPWM , or to a dac on a port ,or to a simple r2r resistor ladder before feeding into an opamp.
the code is weighted so that it moves from 0-255 with 128 being the pseudo zero cross..

/* Average the two sample values so it won't overrange an 8-bit DAC */

send_to_dac(temp_sample / 2);