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# NES/Famicom-oriented modules

## nes_hardware

The `nes_hardware` module is imported automatically on NES targets.

TODO

## nes_mmc4

The `nes_mmc4` module is imported automatically on the NES MMC4 target.
and contains routines related to MMC4 bankswitching.

#### `void set_prg_bank(byte a)`

Changes the $8000-$BFFF PRG bank.

#### `void set_chr_bank0(byte a)`

Changes the CHR bank 0 ($0000-$0fff in the PPU memory space).

The high nibble (0 or 1) selects between `chrrom0` and `chrrom1` segments.
The low nibble L (0-$F) selects a 4K-aligned address in the segment ($L000).

#### `void set_chr_bank1(byte a)`

Changes the CHR bank 1 ($1000-$1fff in the PPU memory space).

The high nibble (0 or 1) selects between `chrrom0` and `chrrom1` segments.
The low nibble L (0-$F) selects a 4K-aligned address in the segment ($L000).

#### `void set_vertical_mirroring()`

Switches nametable mirroring to vertical.

#### `void set_horizontal_mirroring()`

Switches nametable mirroring to horizontal.

## nes_joy

Provides an interface for reading joypads that is compatible with the `joy` module.

#### `alias input_a = input_btn`

1 if A button pressed, 0 id not pressed.

#### `byte input_b`

1 if B button pressed, 0 id not pressed.

#### `byte input_select`

1 if Select button pressed, 0 id not pressed.

#### `byte input_start`

1 if Start button pressed, 0 id not pressed.

#### `void read_joy1()`

Reads the joypad from the port 1.

#### `void read_joy2()`

Reads the joypad from the port 2.

#### `void read_also_joy1()`

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

#### `void read_also_joy2()`

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

#### `void nes_reset_joy()`

Resets the state variables.
Unlike `reset_joy`, this resets all the NES button states.

## nes_joy1_default

Defines the joystick in port 1 as the default joystick.

#### `alias read_joy = read_joy1`