Constants And Defined Types

Declared in: drivers/Drivers.h

This section covers constants and types defined for use by kernel drivers and modules.


Constants

Current Driver API Version

#define B_CUR_DRIVER_API_VERSION N

The B_CUR_DRIVER_API_VERSION constant indicates what version of the driver API your driver will be built to.

See also: "Symbols Drivers Export"

Driver Control Opcodes

ConstantDescription

B_GET_DEVICE_SIZE

Returns a size_t indicating the device size in bytes.

B_SET_DEVICE_SIZE

Sets the device size to the value pointed to by data.

B_SET_NONBLOCKING_IO

Sets the device to use nonblocking I/O.

B_SET_BLOCKING_IO

Sets the device to use blocking I/O.

B_GET_READ_STATUS

Returns true if the device can read without blocking, otherwise false.

B_GET_WRITE_STATUS

Returns true if the device can write without blocking, otherwise false.

B_GET_GEOMETRY

Fills out the specified device_geometry structure to describe the device.

B_GET_DRIVER_FOR_DEVICE

Returns the path of the driver executable handling the device.

B_GET_PARTITION_INFO

Returns a partition_info structure for the device.

B_SET_PARTITION

Creates a user-defined partition. data points to a partition_info structure.

B_FORMAT_DEVICE

Formats the device. data should point to a boolean value: If true, the device is formatted low-level. If it's false, the formatting is <<??>>

B_EJECT_DEVICE

Ejects the device.

B_GET_ICON

Fills out the specified device_icon structure to describe the device's icon.

B_GET_BIOS_GEOMETRY

Fills out a device_geometry structure to describe the device as the BIOS sees it.

B_GET_MEDIA_STATUS

Gets the status of the media in the device by placing a status_t at the location pointed to by data.

B_GET_MEDIA_STATUS returns one of these values in data:

B_NO_ERROR.

The media is ready.

B_DEV_NO_MEDIA.

No media in the device

B_DEV_NOT_READY.

The device isn't ready.

B_DEV_MEDIA_CHANGED.

The media changed since the time that the device was opened, or since the time of the last B_GET_MEDIA_STATUS request.

B_DEV_MEDIA_CHANGE_REQUEST.

The user wants to remove the media.

B_DEV_DOOR_OPEN.

The drive "door" is open.

B_LOAD_MEDIA

Loads the media.

B_GET_BIOS_DRIVE_ID

Returns the BIOS ID for the device.

B_SET_UNINTERRUPTABLE_IO

Prevents control+C from interrupting I/O.

B_SET_INTERRUPTABLE_IO

Allows control+C to interrupt I/O.

B_FLUSH_DRIVE_CACHE

Flushes the drive's cache.

B_GET_NEXT_OPEN_DEVICE

Iterates through open devices; data points to an open_device_iterator.

B_ADD_FIXED_DRIVER

For internal use only.

B_REMOVE_FIXED_DRIVER

For internal use only.

B_AUDIO_DRIVER_BASE

Base for codes in audio_driver.h.

B_MIDI_DRIVER_BASE

Base for codes in midi_driver.h.

B_JOYSTICK_DRIVER_BASE

Base for codes in joystick.h.

B_GRAPHIC_DRIVER_BASE

Base for codes in graphic_driver.h.

B_DEVICE_OP_CODES_END

End of Be-defined control IDs.


Defined Types

device_geometry

typedef struct {
    uint32 bytes_per_sector;
    uint32 sectors_per_track;
    uint32 cylinder_count;
    uint32 head_count;
    uchar device_type;
    bool removable;
    bool read_only;
    bool write_once;
} device_geometry

The device_geometry structure is returned by the B_GET_GEOMETRY driver control function. Its fields are:

FieldDescription

bytes_per_sector

Indicates how many bytes each sector of the disk contains.

sectors_per_track

Indicates how many sectors each disk track contains.

cylinder_count

Indicates the number of cylinders the disk contains.

head_count

Indicates how many heads the disk has.

device_type

Specifies the type of device; there's a list of device type definitions below.

removable

Is true if the device's media can be removed from the drive, and is false otherwise.

read_only

Is true if the media is read-only (such as CD-ROM), or false if the media can be both read from and written.

write_once

Is true if the media can only be written to once (such as CD-recordable), or false if there's no limit to the number of times the media can be written to.

If you need to compute the total size of the device in bytes, you can obtain this figure using the following simple formula:

disk_size = geometry.cylinder_count * geometry.sectors_per_track *
geometry.head_count * geometry.bytes_per_sector;

The device type returned in device_type is one of:

ConstantDescription

B_DISK

Hard disk, floppy disk, etc.

B_TAPE

Tape drive.

B_PRINTER

Printer.

B_CPU

CPU device.

B_WORM

Write-once, read-many device (such as CD-recordable).

B_CD

CD-ROM.

B_SCANNER

Scanner.

B_OPTICAL

Optical device

B_JUKEBOX

Jukebox device.

B_NETWORK

Network device.

device_hooks

typedef struct {
    device_open_hook open;
    device_close_hook close;
    device_free_hook free;
    device_control_hook control;
    device_read_hook read;
    device_write_hook write;
    device_select_hook select;
    device_deselect_hook deselect;
    device_readv_hook readv;
    device_writev_hook writev;
} device_hooks

This structure is used by device drivers to export their function hooks to the kernel.

device_icon

typedef struct {
    int32 icon_size;
    void*icon_data;
} device_icon

When you want to obtain an icon for a specific device, call ioctl() on the open device, specifying the B_GET_ICON opcode. Pass in data a pointer to a device_icon structure in which icon_size indicates the size of icon you want and icon_data points to a buffer large enough to receive the icon's data.

icon_size can be either B_MINI_ICON, in which case the buffer pointed to by icon_data should be large enough to receive a 16x16 8-bit bitmap (256-byte), or B_LARGE_ICON, in which case the buffer should be large enough to receive a 32x32 8-bit bitmap (1024-byte). The most obvious way to set up this buffer would be to create a BBitmap of the appropriate size and color depth and use its buffer, like this:

BBitmap bits(BRect(0, 0, B_MINI_ICON-1, B_MINI_ICON-1, 0, B_CMAP8));
device_icon iconrec;

iconrec.icon_size = B_MINI_ICON;
iconrec.icon_data = bits.Bits();
status_t err = ioctl(dev_fd, B_GET_ICON, &iconrec);

if (err == B_OK) {
   /* enjoy the icon */
   ...
   view->DrawBitmap(bits);
} else {
   /* I don't like icons anyway */
}

driver_path

typedef char driver_path[256];

Used by the B_GET_DRIVER_FOR_DEVICE control function to return the pathname of the specified device.

open_device_iterator

typedef struct {
    uint32 cookie;
    char device[256];
} open_device_iterator

Used by the B_GET_NEXT_OPEN_DEVICE control function. The first time you call this function, your open_device_iterator should have cookie initialized to 0. Then just keep calling it over and over; each time you'll get the name of the next open device. When an error is returned, you're done.

partition_info

typedef struct {
    off_t offset;
    off_t size;
    int32 logical_block_size;
    int32 session;
    int32 partition;
    char device[256];
} partition_info

The partition_info structure describes a disk partition, and is used by the B_GET_PARTITION_INFO and B_SET_PARTITION control commands.

The fields are:

FieldDescription

offset

Is the offset, in bytes, from the beginning of the disk to the beginning of the partition.

size

Is the size, in bytes, of the partition.

logical_block_size

Is the block size with which the file system was written to the partition.

session and partition

Are the session and partition ID numbers for the partition.

device

Is the pathname of the physical device on which the partition is located.

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