Macro RS_DMAX

Each output is a windowed-sinc sum over the taps k = kStart + t around its source position, with x = srcPos - kStart:

weight_t = sin(pi c (x - t)) / (pi (x - t)) * (1 + cos(pi (x - t) / hw)) / 2

sin(pi c (x - t)) and cos(pi (x - t) / hw) expand by the angle-difference formulas into four trig values per output (of x) times tables of the tap angles (of t), made once per call (and the four values themselves are carried from output to output by rotation). The taps are then independent, so they run four to a vector. Outputs whose x is a whole number (a tap at x - t = 0) take the per-tap form below, as do kernels wider than the tables. Outputs are independent and run on the thread pool for longer signals.

largest kStart step advanced by rotation