sg_access_byte
status = sg_access_byte(s_sgb, s_offset + i, &byte, false);
status = sg_access_byte(d_sgb, d_offset + i, &byte, true);
status_t sg_access_byte(sg_buffer *sgb, off_t offset, uchar *byte, bool b_set);
if( B_OK != sg_access_byte(sgb, 0, &mode_data_len_msb, false) ||
B_OK != sg_access_byte(sgb, 6, &block_descr_len_msb, false) ||
if(B_OK == (status = sg_access_byte(sgb, 2, &device_spec_params, false))){
status = sg_access_byte(sgb, 2, &device_spec_params, true);