Multiple control mixer - internal structure?

How is the "multiple control mixer" (no slew) implemented internally? If I have, say, six inputs, is each input multiplied independently by the gain vailue, and then the results are summed one by one? In what order is this done? (top to bottom? bottom to top? something else?) Are the internal registers within this block 5.23?

I'm trying to track down a subtle clipping issue, which could either be overflow or underflow, and I think it may be in this block. I want to be sure that all intermediate calculation values are within a valid range (presumably -16 to 16) - not just input gained values but also intermediate sums. For example, if one clips high (or will it overflow and wrap?), and another is low, they might cancel and my output will have distortion, even though it's still within range.

This is for the ADAU1701.

Weird question, but an important one I think.

Audio Signal Processors

SigmaDSP Audio Processors

adau1701