e_hidx
e->e_hidx = 0;
e->e_hidx = nfr % e->e_nframes;
e->e_hidx = 0;
st->st_hidx.value.ui32 = e->e_hidx;
uint_t hidx = eng->e_hidx; \
uint_t part = min(resid, eng->e_nframes - eng->e_hidx);
eng->e_hidx += part;
if (eng->e_hidx == eng->e_nframes)
eng->e_hidx = 0;