# Nightloader Driver Structure

This documentation file explains the format of a native driver slot
for the Nightloader on the i386 architecture.

| Offset | Length    |        Name of Field              |
| ------ | --------- | --------------------------------- |
|   0    |     8     |  Driver Identifier                |
|   8    |     2     |  Format Version                   |
|   10   |     2     |  Driver Version                   |
|   12   |     2     |  Number of Functionalities        |
|   16   |     4     |  Functionality Table Offset       |

1. Driver Identifier  
   The driver identifier is used to uniquely identify a driver. It can
   be chosen by a driver's developer, but should suggest what kind of
   driver is contained in that slot, for the sake of clarity.

2. Format Version  
   The version of the driver slot's standardized structures such as
   the rest of the header, the functionality table and others that
   the future might bring.  
   The first byte of this structure tells the major version, the
   second one tells the minor version. No version patches are needed.

3. Driver Version  
   Version of the driver, as seen by the driver's developer.  
   The first byte of this structure should be the major version, the
   second one the minor version. No version patches are needed.
   
4. Number of Functionalities  
   How many entries the functionality table contains. The table of
   functionalities contains functions with standardized arguments,
   actions and return types for interfacing with the driver.

5. Functionality Table Offset  
   Offset *from the start of the driver slot* to the functionality
   table. It may be wise to keep this a bit further away from the
   header to prevent the need for more changes if the header structure
   changes in a future version.

## Functionality Structure

Functionalities in the functionality table have a structure defined in
the following table:

| Offset |  Length   |  Name of Field                    |
| ------ | --------- | --------------------------------- |
|   0    |     2     |  Function Category                |
|   2    |     2     |  Exact Function                   |
|   4    |     4     |  Function Pointer                 |

> The functionality table as it is found in any correct driver is a
> tightly packed array of those structures with as many elements as
> were promised in the corresponding header field.

## Driver Functionality Categories

The table below contains links to the driver functionality categories:

|  Id    |  Category                                     |
| ------ | --------------------------------------------- |
|  0x1   |  [Basic Text](./textwriter-functions.md)      |
|  0x2   |  [Text Window](./window-functions.md)         |
|  0x3   |  [Logger](./logger-functions.md)              |
|  0x4   |  [Pixel Graphics](./graphic-functions.md)     |
|  0x5   |  [Pixel Fonts](./pixel-font-functions.md)     |
|  0x10  |  [PCI](./pci-functions.md)                    |
|  0x11  |  [PCIe](./pcie-functions.md)                  |
|  0x12  |  [NVMe](./pcie-functions.md)                  |
|  0x20  |  [USB](.usb/-functions.md)                    |
|  0x30  |  [Storage](./storage-functions.md)            |
|  0x40  |  [Filesystem](./filesystem-functions.md)      |