VORTEX_MIX_VOL_A
a = hwread(vortex->mmio, VORTEX_MIX_VOL_A + (mix << 2)) & 0xff;
hwwrite(vortex->mmio, VORTEX_MIX_VOL_A + (mix << 2), vol);
addr = VORTEX_MIX_VOL_A + 0x3c;