PDSK_READPHYSTRACK
- Category
- IOCTL_PHYSICALDISK (09h)
- Function
- PDSK_READPHYSTRACK (64h)
- Description
- Read Physical Track
Description
Performs a physical read track.
Command Information
A bit field as follows:
- Bit 0: If clear (0), the track layout contains nonconsecutive sectors or does not start with Sector 1. If set (1), the track layout starts with Sector 1 and contains only consecutive sectors.
- All other bits are reserved and must be set to 0.
Head
The physical head on the drive that performs the operation.
Cylinder
The cylinder for the read.
First Sector
The logical sector number within the Track Layout Table that starts the I/O operation. Note that the sector numbers start with 0. For example, the third sector is number 2.
Number of Sectors
The number of sectors to read (up to the maximum specified in the track table; the IOCtl subfunctions do not step heads/tracks).
Track Layout Table
| Field | Length |
|---|---|
| Sector Number for Sector 1 | WORD |
| Sector Size for Sector 1 | WORD |
| Sector Number for Sector 2 | WORD |
| Sector Size for Sector 2 | WORD |
| Sector Number for Sector 3 | WORD |
| Sector Size for Sector 3 | WORD |
| ... | ... |
| Sector number for Sector n | WORD |
| Sector size for Sector n | WORD |
Parameter Packet Format
| Field | Length | C Datatype |
|---|---|---|
| Command Information | BYTE | BYTE |
| Head | WORD | USHORT |
| Cylinder | WORD | USHORT |
| First Sector | WORD | USHORT |
| Number of Sectors | WORD | USHORT |
| Track Layout Table | BYTES | BYTE[] |
Related C Data Structure: The TRACKLAYOUT data structure can be used by C programmers. To include this data structure in your file, make sure INCL_DOSDEVIOCTL is defined before you include OS2.H.
Data Packet Format
The Data Packet is a buffer. The buffer must be large enough to hold requested data.
| Field | Length | C Datatype |
|---|---|---|
| Buffer | BYTES | UCHAR[] |
Returns
Possible values are shown in the following list:
| Code | Description |
|---|---|
| 0 | NO_ERROR |
| 1 | ERROR_INVALID_FUNCTION |
| 6 | ERROR_INVALID_HANDLE |
| 15 | ERROR_INVALID_DRIVE |
| 31 | ERROR_GEN_FAILURE |
| 87 | ERROR_INVALID_PARAMETER |
| 111 | ERROR_BUFFER_OVERFLOW |
| 115 | ERROR_PROTECTION_VIOLATION |
| 117 | ERROR_INVALID_CATEGORY |
| 119 | ERROR_BAD_DRIVER_LEVEL |
| 163 | ERROR_UNCERTAIN_MEDIA |
| 165 | ERROR_MONITORS_NOT_SUPPORTED |
Remarks
This function is used to perform the operations specified on the physical drive in this request. This is similar to the Category 08h commands, except that the I/O is done offset from the beginning of the physical drive instead of from the beginning of the extended volume associated with the unit number (Category 08h). The Track Layout Table passed in the Parameter Packet is used to determine the sector number, which is passed on to the disk controller for the operation. In cases where the sectors are oddly numbered or are nonconsecutive, this request breaks into n single sector operations and reads one sector at a time. Note also that the device driver does not correctly read a non-512 byte sector if the READ operation would generate a DMA violation error. Applications should be written so that this error does not occur. The sector table that is specified provides information that is used during the READ track operation.