First of all go through some document to understand the I2C protocol/waveforms and details of the signals and how they are working? You may refer NXP's LPC9xx series microcontroller user guide/data sheet for understanding, how an 8 bit controller incorporated I2C interface?
I had developed I2C interface design for simple Tx/Rx purpose, inspired from the LPC9xx controllers. It is capable for point to point communication. You can find the files attached. Its just a hobby project and please don't expect a strong professional touch. Also the test bench is very basic!
Its not fully up and tested yet, the receiver have some minor problems. But the transmitter is working. You can look at it for reference.