Modifying the salary slip

I am Implementing the loan feature in the salary slip. I have checked the code of payroll, while creating the salary slips in payroll the amounts are automatically calculated and inserted in the db. I am not able to find the code corresponding to amounts.
Thanks in advance

Thanks for your reply @nabinhait, here in salary slip, Iam not able to find the method you have mentioned.

This function is in develop branch

I got following link while searching for loan management

Is this the way it is being developed. If yes when it will be moved to master.
Thank you

It will be available in V8 which will be released on 16th-17th March, 2017.

Thank you @KanchanChauhan.