Comment 12 for bug 1743795

Heinz is right. The existing code would work correctly only if

(a) it were a signed integer, which it isn't, and

(b) the C % operator were defined as "modulo" in the mathematical sense i.e. always resulting in a value between 0 and (rhs-1), which it doesn't have to be, see https://stackoverflow.com/questions/4003232/how-to-code-a-modulo-operator-in-c-c-obj-c-that-handles-negative-numbers

Thus another correct fix is

if(!fifo)
   offset = (offset + nsam - 1) % nsam;