Drivers Index

Constants and Defined Types

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

Constants

Current Driver API Version

Declared in: <drivers/Drivers.h>

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

Declared in: <drivers/Drivers.h>

Constant Meaning
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 this is true, the device is formatted low-level. If it's false, <<<unclear>>>
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_LOAD_MEDIA Loads the media, if this is supported. <<<what does that mean?>>>
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.

B_GET_MEDIA_STATUS can return the following values:

Defined Types

device_geometry

Declared in: <drivers/Drivers.h>




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:

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:

Constant Meaning
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 (like CD-recordable)
B_CD CD-ROM
B_SCANNER Scanner
B_OPTICAL Optical device
B_JUKEBOX Jukebox device
B_NETWORK Network device

device_hooks

Declared in: <drivers/Drivers.h>




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

Declared in: <drivers/Drivers.h>




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

Declared in: <drivers/Drivers.h>

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

Declared in: <drivers/Drivers.h>




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

Declared in: <drivers/Drivers.h>




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:

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.

Drivers Table of Contents

Drivers Index

The Be Book,
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for BeOS Release 5.

Constant	Meaning
`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 this is `true`, the device is formatted low-level. If it's `false`, <<<unclear>>>
`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_LOAD_MEDIA`	Loads the media, if this is supported. <<<what does that mean?>>>
`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.

Constant	Meaning
`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 (like CD-recordable)
`B_CD`	CD-ROM
`B_SCANNER`	Scanner
`B_OPTICAL`	Optical device
`B_JUKEBOX`	Jukebox device
`B_NETWORK`	Network device