/* Calcite, src/kernel/ipc-dgram.h
 * Copyright 2025-2026 Benji Dial
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
 * for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program. If not, see <https://www.gnu.org/licenses/>.
 */

#pragma once

#include "scheduler.h"

#include <kernel-public/ipc.h>

//must be a multiple of 4
#define IPC_DGRAM_BOX_BUFFER_LENGTH 1024

struct ipc_dgram_box {

  int is_receiver_held;
  int is_private;
  int private_sides;

  int is_someone_waiting_to_receive;
  struct continuation_info waiting_to_receive;

  struct continuation_queue waiting_to_send;

  int buffer_read_pointer;
  int buffer_read_available;

  //packets are of the form:
  //  int size;
  //  uint8_t packet[size];
  //  uint8_t padding[size % 4 == 0 ? 0 : 4 - size % 4];
  uint8_t buffer[IPC_DGRAM_BOX_BUFFER_LENGTH];

};

struct ipc_dgram_box *get_ipc_dgram_box(const char *address);

//waits until a packet is available, then returns the size of that packet.
//returns -1 if someone is already waiting.
int get_ipc_dgram_size(struct ipc_dgram_box *box);

//should only be called just after get_ipc_dgram_size
//(i.e. with no intervening continuation resumptions)
void receive_ipc_dgram(struct ipc_dgram_box *box, void *buffer);

//only returns IPR_SUCCESS or IPR_TOO_BIG
enum ipc_dgram_result send_ipc_dgram(struct ipc_dgram_box *box, const void *data, int bytes);

uint64_t syscall_ipc_create_private_dgram_pipe();
enum ipc_dgram_result syscall_ipc_create_private_dgram_receiver(
  uint64_t id, ipc_dgram_receiver_handle_t *handle_out);
enum ipc_dgram_result syscall_ipc_create_private_dgram_sender(
  uint64_t id, ipc_dgram_sender_handle_t *handle_out);

void destroy_ipc_dgram_box(struct ipc_dgram_box *box);