SIREG_DMA_CNTL
SIREG_WRITE(ncr_sc, SIREG_DMA_CNTL, 0);
SIREG_WRITE(ncr_sc, SIREG_DMA_CNTL, 0);
SIREG_WRITE(ncr_sc, SIREG_DMA_CNTL, 0);
SIREG_WRITE(ncr_sc, SIREG_DMA_CNTL, (uint16_t)(xlen & 0xFFFF));
SIREG_WRITE(ncr_sc, SIREG_DMA_CNTL, 0);