| Platform SDK: Win32 API |
Sets the dpb_free_cnt and dpb_next_free fields in the DPB.
This sub-function is called when the SetDPB_Function member of the SDPDFormatStruc structure is set to 0.
Clears the carry flag and sets the dpb_free_cnt and dpb_next_free fields in the DPB based upon the values in the SetDPB_Value1 and SetDPB_Value2 fields within the Set_DPB_ForFormat structure.
The value in the SetDPB_Value1 member of the Set_DPB_ForFormat structure determines the following results.
| SetDPB_Value1 setting | Result within DPB |
| 0 | Does not change the dpb_free_cnt member. |
| 0xFFFFFFFF | Sets dpb_free_cnt to unknown. |
| (any other value) | Sets dpb_free_cnt to the specified value if it is a valid cluster count for the drive,. |
The free cluster count cannot be explicitly set to zero by this call. This can only be done by setting SetDPB_Value1 to 0xFFFFFFFF, which forces the free space to be re-computed. Also, setting this value improperly causes the free count value to be reported improperly by the GetDiskFreeSpace function. The settings of 0 or 0xFFFFFFFF are recommended.
| SetDPB_Value2 setting | Result within DPB |
| 0 | Does not change the dpb_next_free member. |
| 0xFFFFFFFF | Sets dpb_next_free to force the cluster search to begin at the beginning of the FAT. |
| (any other value) | Sets dpb_next_free to the given value if it is a valid cluster number for the drive. This causes the search for free clusters to begin at the specified cluster. |
The assembler calling sequence for all Int 21h 7304h sub-functions is almost identical. See the main listing for a sample. (Int 21h Function 7304h Set_DPBForFormat)