frac32buffer in0
frac32buffer in1
frac32buffer in2
frac32buffer out0
frac32buffer out1
frac32buffer out2
// +--
// -+-
// --+
// 2/3 1/3 q32 *2
int32_t y = ___SMMUL(1431655765, inlet_in0 + inlet_in1 + inlet_in2) << 1;
outlet_out0 = inlet_in0 - y;
outlet_out1 = inlet_in1 - y;
outlet_out2 = inlet_in2 - y;