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# Commander X16-oriented modules

**WARNING!** Commander X16 is not yet a finalised design.
Therefore, both the device itself and the modules for its support may change at any moment.

## x16_kernal module

The `x16_kernal` module is imported automatically on the X16 target.

Currently, it automatically imports the [`c64_kernal` module](./c64.md).

## `x16_hardware` module

The `x16_hardware` module is imported automatically on the X16 target.

#### `void set_ram_bank(byte)`

Switches the RAM segment at $A000-$BFFF.

#### `void set_rom_bank(byte)`

Switches the ROM segment at $C000-$DFFF.

#### `void vera_poke(int24 address, byte value)`

Writes a byte into the VERA memory space.

#### `byte vera_peek(int24 address)`

Reads a byte from the VERA memory space.

#### `void vera_fill(int24 address, byte value, word size)`

Writes `size` bytes into the VERA memory space.

#### `void vera_upload(int24 address, pointer source, byte size)`
#### `void vera_upload_large(int24 address, pointer source, word size)`

Copies `size` bytes from the RAM at address `source` into the VERA memory space at address `address`.

#### `struct vera_layer_setup`

Hardware register values for a video layer:

    byte ctrl0
    byte ctrl1
    word map_base
    word tile_base
    word hscroll
    word vscroll

#### `void set_vera_layer1(pointer.vera_layer_setup)`

Sets up the layer 1.

#### `void set_vera_layer2(pointer.vera_layer_setup)`

Sets up the layer 2.
    
#### `struct vera_sprite_data`

Hardware register values for a sprite:

    word address
    word x
    word y
    byte ctrl0
    byte ctrl1
    
#### `const int24 VERA_COMPOSER_CTRL`
#### `const int24 VERA_PALETTE`
#### `const int24 VERA_LAYER_1`
#### `const int24 VERA_LAYER_2`
#### `const int24 VERA_SPRITE_CTRL`
#### `const int24 VERA_SPRITES`

Various addresses in the VERA memory space.

## `x16_joy` module

The `x16_joy` module implements a joystick driver compatible with the `joy` module.

#### `void read_joy1()`

Reads the joystick from the port 1.

#### `void read_joy2()`

Reads the joystick from the port 1.

#### `void read_also_joy1()`

Reads the joystick from the port 1 and adds its readouts to the current readouts.

#### `void read_also_joy2()`

Reads the joystick from the port 2 and adds its readouts to the current readouts.

#### `byte input_*`

The following variables have the value 1 if the key is pressed and 0 if not:

**Warning:** The assignment of NES controller buttons and keyboard keys may change in the future.   

Variable       | SNES controller | NES controller | Keyboard (joy 1 only)
---------------|-----------------|----------------|----------------------
`input_a`      | A               |                |
`input_b`      | B               | A              | Ctrl
`input_x`      | X               | B              | Alt
`input_y`      | Y               |                |
`input_start`  | Start           | Start          | Enter
`input_select` | Select          | Select         | Space
`input_l`      | L               |                |
`input_r`      | R               |                |
 
 
`input_b` is an alias for `input_btn`. Single-button games should use `input_btn` for compatibility.
 
## x16_joy1_default module

Defines the joystick in port 1 as the default joystick.

#### `alias read_joy = read_joy1`