BLK_CUR_BLKNUM
BLK_CUR_BLKNUM = 0;
BLK_CUR_BLKNUM = 0;
BLK_CUR_BLKNUM++;
if (BLK_CUR_BLKNUM >= BLK_BLKLENGTH (BLK_CUR_BLKLIST))
BLK_CUR_BLKNUM = 0;
size = ((BLK_BLKLENGTH (BLK_CUR_BLKLIST) - BLK_CUR_BLKNUM)
devread (BLK_BLKSTART (BLK_CUR_BLKLIST) + BLK_CUR_BLKNUM,