punktfunk/include/lumen_core.h

/* lumen-core C ABI — see crates/lumen-core/src/abi.rs */

#ifndef LUMEN_CORE_H
#define LUMEN_CORE_H

#pragma once

/* Generated by cbindgen from lumen-core. Do not edit by hand. */

#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdlib.h>

// Bump on any breaking change to the [C ABI](crate::abi). Mirrors
// `lumen_abi_version()` and is checked by clients before use.
#define ABI_VERSION 1

// 16-byte AEAD authentication tag appended by GCM.
#define TAG_LEN 16

// Wire tag distinguishing an input datagram from a video packet.
#define INPUT_MAGIC 200

// Fixed serialized size of an [`InputEvent`] on the wire (tag + fields).
#define INPUT_WIRE_LEN (((((1 + 1) + 4) + 4) + 4) + 4)

// Identifies a lumen video packet (vs. an input datagram, see [`crate::input`]).
#define LUMEN_MAGIC 201

#define FLAG_PIC 1

#define FLAG_EOF 2

#define FLAG_SOF 4

// Largest UDP datagram the core will send or accept. `Config::validate` bounds
// `shard_payload` so `HEADER_LEN + shard_payload + CRYPTO_OVERHEAD ≤ MAX_DATAGRAM_BYTES`.
#define MAX_DATAGRAM_BYTES 2048

// Stable C ABI status codes. `Ok` is 0; all errors are negative so callers can
// test `rc < 0`. Do not renumber existing variants — only append.
enum LumenStatus
#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  : int32_t
#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
 {
    LUMEN_STATUS_OK = 0,
    LUMEN_STATUS_INVALID_ARG = -1,
    LUMEN_STATUS_FEC = -2,
    LUMEN_STATUS_CRYPTO = -3,
    LUMEN_STATUS_BAD_PACKET = -4,
    LUMEN_STATUS_NO_FRAME = -5,
    LUMEN_STATUS_UNSUPPORTED = -6,
    LUMEN_STATUS_IO = -7,
    LUMEN_STATUS_NULL_POINTER = -8,
    LUMEN_STATUS_PANIC = -99,
};
#ifndef __cplusplus
#if __STDC_VERSION__ >= 202311L
typedef enum LumenStatus LumenStatus;
#else
typedef int32_t LumenStatus;
#endif // __STDC_VERSION__ >= 202311L
#endif // __cplusplus

// Kinds of input event. `#[repr(u8)]` so it crosses the C ABI as a byte tag.
enum LumenInputKind
#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  : uint8_t
#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
 {
    LUMEN_INPUT_KIND_KEY_DOWN = 0,
    LUMEN_INPUT_KIND_KEY_UP = 1,
    // Relative motion: `x`/`y` carry `dx`/`dy`.
    LUMEN_INPUT_KIND_MOUSE_MOVE = 2,
    // Absolute motion: `x`/`y` carry pixel coordinates.
    LUMEN_INPUT_KIND_MOUSE_MOVE_ABS = 3,
    LUMEN_INPUT_KIND_MOUSE_BUTTON_DOWN = 4,
    LUMEN_INPUT_KIND_MOUSE_BUTTON_UP = 5,
    // `x` carries the (signed) scroll delta.
    LUMEN_INPUT_KIND_MOUSE_SCROLL = 6,
    LUMEN_INPUT_KIND_GAMEPAD_BUTTON = 7,
    // `code` = axis id, `x` = axis value.
    LUMEN_INPUT_KIND_GAMEPAD_AXIS = 8,
};
#ifndef __cplusplus
#if __STDC_VERSION__ >= 202311L
typedef enum LumenInputKind LumenInputKind;
#else
typedef uint8_t LumenInputKind;
#endif // __STDC_VERSION__ >= 202311L
#endif // __cplusplus

// Opaque session handle. Pointer-only from C.
typedef struct LumenSession LumenSession;

// Forward-compatible session configuration. The caller MUST set `struct_size` to
// `sizeof(LumenConfig)`; the core uses it to detect ABI skew.
typedef struct {
    uint32_t struct_size;
    // 0 = host, 1 = client.
    uint32_t role;
    // 1 = P1 (GameStream-compatible), 2 = P2 (`lumen/1`).
    uint32_t phase;
    // 0 = GF(2⁸), 1 = GF(2¹⁶).
    uint32_t fec_scheme;
    uint32_t fec_percent;
    uint32_t max_data_per_block;
    uint32_t shard_payload;
    // Non-zero enables AES-128-GCM.
    uint32_t encrypt;
    uint8_t key[16];
    uint8_t salt[4];
    // Test hook for the loopback transport; 0 in production.
    uint32_t loopback_drop_period;
    // Largest encoded access unit the receiver will accept (bounds reassembler memory).
    uint64_t max_frame_bytes;
} LumenConfig;

// A reassembled access unit. `data`/`len` borrow session-owned memory valid until the
// next `lumen_client_poll_frame`/`lumen_session_free` on the same session.
typedef struct {
    const uint8_t *data;
    uintptr_t len;
    uint32_t frame_index;
    uint64_t pts_ns;
    uint32_t flags;
} LumenFrame;

// A single input event. `#[repr(C)]` — shared verbatim with the C ABI as
// `LumenInputEvent`.
typedef struct {
    LumenInputKind kind;
    uint8_t _pad[3];
    // keycode / button id / axis id, depending on `kind`.
    uint32_t code;
    // x / dx / abs-x / axis-value / scroll-delta, depending on `kind`.
    int32_t x;
    // y / dy / abs-y, depending on `kind`.
    int32_t y;
    // modifier bitmask or gamepad index.
    uint32_t flags;
} LumenInputEvent;

// Snapshot of session counters.
typedef struct {
    uint64_t frames_submitted;
    uint64_t frames_completed;
    uint64_t frames_dropped;
    uint64_t packets_sent;
    uint64_t packets_received;
    uint64_t packets_dropped;
    uint64_t fec_recovered_shards;
    uint64_t bytes_sent;
    uint64_t bytes_received;
} LumenStats;

#ifdef __cplusplus
extern "C" {
#endif // __cplusplus

// Current ABI version. Mismatch with [`crate::ABI_VERSION`] means incompatible core.
uint32_t lumen_abi_version(void);

// Create a session over a real UDP transport (`local`/`peer` are `host:port` strings).
// Returns NULL on error.
//
// # Safety
// `cfg`, `local`, `peer` must be valid pointers; the strings must be NUL-terminated.
LumenSession *lumen_session_new(const LumenConfig *cfg, const char *local, const char *peer);

// Create a connected host+client session pair sharing an in-process loopback
// transport. Test/dev only — exercises the full FEC + framing path without a network.
//
// # Safety
// All four pointers must be valid; the two out-params receive owned handles.
LumenStatus lumen_test_loopback_pair(const LumenConfig *host_cfg,
                                     const LumenConfig *client_cfg,
                                     LumenSession **out_host,
                                     LumenSession **out_client);

// Free a session handle. Safe to call with NULL.
//
// # Safety
// `s` must be a handle from `lumen_session_new`/`lumen_test_loopback_pair`, freed once.
void lumen_session_free(LumenSession *s);

// Host: FEC-protect, packetize, seal and send one encoded access unit.
//
// # Safety
// `s` is a valid host handle; `data` points to `len` readable bytes (or `len == 0`).
LumenStatus lumen_host_submit_frame(LumenSession *s,
                                    const uint8_t *data,
                                    uintptr_t len,
                                    uint64_t pts_ns,
                                    uint32_t flags);

// Client: poll for the next reassembled access unit. Returns [`LumenStatus::NoFrame`]
// when nothing is ready yet. On `Ok`, `*out` borrows session memory until the next poll.
//
// # Safety
// `s` is a valid client handle; `out` points to a writable `LumenFrame`.
LumenStatus lumen_client_poll_frame(LumenSession *s, LumenFrame *out);

// Client: serialize and send one input event to the host.
//
// # Safety
// `s` is a valid client handle; `ev` points to a valid [`InputEvent`].
LumenStatus lumen_send_input(LumenSession *s, const LumenInputEvent *ev);

// Register the host-side input callback (pass a NULL fn pointer to clear). The callback
// fires from within [`lumen_host_poll_input`], on the calling thread.
//
// # Safety
// `s` is a valid host handle; `user` is passed back verbatim to `cb`.
LumenStatus lumen_set_input_callback(LumenSession *s, void (*cb)(const LumenInputEvent *event,
                                                                 void *user), void *user);

// Host: drain all pending input events, invoking the registered callback for each.
// Returns the count dispatched (≥ 0), or a negative [`LumenStatus`] on error.
//
// # Safety
// `s` is a valid host handle.
int32_t lumen_host_poll_input(LumenSession *s);

// Copy session counters into `*out`.
//
// # Safety
// `s` is a valid handle; `out` points to a writable `LumenStats`.
LumenStatus lumen_get_stats(LumenSession *s, LumenStats *out);

#ifdef __cplusplus
}  // extern "C"
#endif  // __cplusplus

#endif  /* LUMEN_CORE_H */