SFXGE_RX_FPP_MASK
id = CPU->cpu_seqid & SFXGE_RX_FPP_MASK;
id = start = (CPU->cpu_seqid + 1) & SFXGE_RX_FPP_MASK;
id = (id + 1) & SFXGE_RX_FPP_MASK;
unsigned int, (id - 1) & SFXGE_RX_FPP_MASK,