getting sample data from a buffer~

ok, so my idea is that i want to take a waveform, and then do something mathematically to it with another waveform.
one idea is that i want to be able to take the y value of all the samples involved in one buffer~ i want to do the same with another sound file like a squiggly wave or something, i then want to take buffer 1, at sample position 1, say its y value is 0.86. i want to take buffer 2 at sample position 1, say its y value is 0.42, then do some math on it, like addition or subtraction and then save that result elsewhere.
i then do that for sample position 2 of buffer 1 and 2, sample positon 3, etc etc etc until its all read and the new values have been placed in to a new buffer that can be played.