#GBA Link Connection (C Port)

This is a C port of gba-link-connection by rodri042, a library which makes it easy to add multiplayer support to Game Boy Advance homebrew games.

Notes:

• Depends on libtonc.
• Uses malloc when creating the connection with lc_init, to allocate internal buffers.
• The example uses devkitARM, but it could work with any compatible toolchain.

#Usage

A Link Cable connection for Multi-player mode.

Usage:

1) Include this header in your main.c file, then declare and initialise a connection.

#include "link_connection.h"

LinkConnection conn;

// ...
  
  LinkConnectionSettings settings = {
    .baud_rate = BAUD_RATE_1,
    .timeout = 3,
    .remote_timeout = 5,
    .buffer_len = 30,
    .interval = 50,
    .send_timer_id = 3,
  };
  conn = lc_init(settings);
  
  // Alternatively you can pass in memory for 5 buffers manually:
  //
  // EWRAM_DATA u16 buffers[LINK_TOTAL_BUFFERS * 30];
  // ...
  // conn = lc_init_manual(settings, buffers);

2) Add the required interrupt service routines:

void onVBlank() {
  lc_on_vblank(&conn);
}
void onSerial() {
  lc_on_serial(&conn);
}
void onTimer() {
  lc_on_timer(&conn);
}

// ...

  irq_init(NULL);
  
  irq_add(II_VBLANK, onVBlank);
  irq_add(II_SERIAL, onSerial);
  irq_add(II_TIMER3, onTimer);

Note: the above snippet uses Tonc's IRQ functions, but it's recommended to use UGBA's for improved reliability. Check the example directory in this repo to see how to do that.

3) Start the library with:

lc_activate(&conn);

4) Send/read messages by using:

lc_send(&conn, data)
lc_is_connected(&conn)
lc_has_message(&conn, player_id)
lc_read_message(&conn, player_id)

Restrictions on sent data: 0xFFFF and 0x0000 are reserved values, so don't use them (they mean 'disconnected' and 'no data' respectively).

5) If you used lc_init, be sure to free the internal buffers:

lc_destroy(&conn);