AV_SCRATCH_0
amvdec_write_dos(core, AV_SCRATCH_0, (h264->max_refs << 24) |
status = amvdec_read_dos(core, AV_SCRATCH_0);
amvdec_write_dos(core, AV_SCRATCH_0, 0);
ret = amvdec_set_canvases(sess, (u32[]){ AV_SCRATCH_0, 0 },