1981 	BYTE sum			/* Checksum of the corresponding SFN */  argument
1988 	dir[LDIR_Chksum] = sum;			/* Set checksum */
2075 	BYTE sum = 0;  local
2079 		sum = (sum >> 1) + (sum << 7) + *dir++;
2081 	return sum;
2098 	WORD sum;  local
2102 	for (i = sum = 0; i < szblk; i++) {
2106 			sum = ((sum & 1) ? 0x8000 : 0) + (sum >> 1) + dir[i];
2109 	return sum;
2119 	WORD sum = 0;  local
2124 		sum = ((sum & 1) ? 0x8000 : 0) + (sum >> 1) + (chr & 0xFF);
2125 		sum = ((sum & 1) ? 0x8000 : 0) + (sum >> 1) + (chr >> 8);
2127 	return sum;
2134 	DWORD sum			/* Previous sum value */  argument
2137 	sum = ((sum & 1) ? 0x80000000 : 0) + (sum >> 1) + dat;
2138 	return sum;
2336 	BYTE ord = 0xFF, sum = 0xFF;  local
2370 						sum = dp->dir[LDIR_Chksum];
2375 …	ord = (b == ord && sum == dp->dir[LDIR_Chksum] && pick_lfn(fs->lfnbuf, dp->dir)) ? ord - 1 : 0xFF;
2377 					if (ord != 0 || sum != sum_sfn(dp->dir)) {	/* Is there a valid LFN? */
2413 	BYTE a, ord, sum;  local
2440 	ord = sum = 0xFF; dp->blk_ofs = 0xFFFFFFFF;	/* Reset LFN sequence */
2458 						sum = dp->dir[LDIR_Chksum];	/* Sum of the SFN */
2461 …		ord = (c == ord && sum == dp->dir[LDIR_Chksum] && cmp_lfn(fs->lfnbuf, dp->dir)) ? ord - 1 : 0xFF;
2464 				if (ord == 0 && sum == sum_sfn(dp->dir)) break;	/* LFN matched? */
2495 	BYTE sn[12], sum;  local
2552 			sum = sum_sfn(dp->fn);	/* Checksum value of the SFN tied to the LFN */
2556 				put_lfn(fs->lfnbuf, dp->dir, (BYTE)n_ent, sum);
6044 		DWORD szb_bit, szb_case, sum, nbit, clu, clen[3];  local
6072 		sum = 0;							/* Table checksum to be stored in the 82 entry */
6096 			sum = xsum32(buf[i + 0] = (BYTE)ch, sum);	/* Put it into the write buffer */
6097 			sum = xsum32(buf[i + 1] = (BYTE)(ch >> 8), sum);
6148 		st_dword(buf + SZDIRE * 2 + 4, sum);			/*  sum */
6180 			for (i = sum = 0; i < ss; i++) {		/* VBR checksum */
6181 …f (i != BPB_VolFlagEx && i != BPB_VolFlagEx + 1 && i != BPB_PercInUseEx) sum = xsum32(buf[i], sum);
6188 				for (i = 0; i < ss; sum = xsum32(buf[i++], sum)) ;	/* VBR checksum */
6194 				for (i = 0; i < ss; sum = xsum32(buf[i++], sum)) ;	/* VBR checksum */
6198 			for (i = 0; i < ss; i += 4) st_dword(buf + i, sum);		/* Fill with checksum value */