ludic/selfhost/emit_ecs.ludic

# emit_ecs.ludic — ECS storage and the entity allocator. For each component:
# a %Cmp_ layout, a dense @S_ store, and an @H_ "has this component" array.
# Entities are integer handles; L_alloc reuses freed slots. Mirrors the ECS
# parts of compiler/back/ir_decl.c.

const MAX_ENT: int = 1024

function has_systems() -> bool {
  var i = 0
  while i < len(prog) { if prog[i].kind == N_SYS { return true };  i = i + 1 }
  return false
}
function has_models() -> bool {
  var i = 0
  while i < len(prog) { if prog[i].kind == N_ARCH { return true };  i = i + 1 }
  return false
}
# N5: does the program have an `entry` block? A game with both handlers and an
# `entry` drives its own loop (calling tick_fixed/tick_render), instead of the
# compiler's auto frame loop. A game with handlers and no entry uses the auto-loop.
function has_entry() -> bool {
  var i = 0
  while i < len(prog) { if prog[i].kind == N_MAIN { return true };  i = i + 1 }
  return false
}
# Does this program run the ECS? A property alone no longer answers that — the
# same `property` keyword also declares plain `new`-allocated records (the merged
# `struct`). A program uses the ECS when it has a handler or a model; a tool that
# only declares record types and functions does not, and gets no entity storage,
# allocator, snapshot or runtime splice.
function has_ecs() -> bool { return has_systems() or has_models() }

function emit_ecs_storage() -> void {
  emith("@L_running = internal global i32 1\n")
  emith("@L_key = internal global i32 0\n")
  emith("@L_frame = internal global i32 0\n")
  if len(g_scenes) > 0 { emith("@L_scene = internal global i32 0\n") }   # active base scene id
  emith("@L_entc = internal global i32 0\n")
  let me = itoa(MAX_ENT)
  emith(`@L_alive = internal global [{me} x i32] zeroinitializer\n`)
  emith(`@L_kind = internal global [{me} x i32] zeroinitializer\n`)
  emith(`@L_freelist = internal global [{me} x i32] zeroinitializer\n`)
  emith("@L_freen = internal global i32 0\n")
  # NETWORKING role registers (N3/N5): a runtime sets these; offline they hold the
  # single-player default — @L_role=1 (this peer is the authority), local id 0.
  # Emitted only when a networking feature is used, so non-networked builds are
  # byte-identical (§8). @L_owner_arr is the per-entity network owner (N3, @Owned).
  if net_any() {
    emith("@L_role = internal global i32 1\n")       # 1 = server/authority (offline default)
    emith("@L_localid = internal global i32 0\n")    # this peer's id
  }
  if net_has_owned() { emith(`@L_owner_arr = internal global [{me} x i32] zeroinitializer\n`) }
  var i = 0
  while i < len(prog) {
    let c = prog[i]
    # per-entity storage for a property (its %Cmp_ layout is emitted in the
    # header). Every property in an ECS program is a component today; a property
    # used only via `new` would not need these, but no such program mixes the two.
    if c.kind == N_COMP {
      emith(`@S_{c.s} = internal global [{me} x %Cmp_{c.s}] zeroinitializer\n`)
      emith(`@H_{c.s} = internal global [{me} x i8] zeroinitializer\n`)
    }
    # one enabled-flag global per model and per handler (default enabled)
    if c.kind == N_ARCH { emith(`@ME_{c.s} = internal global i32 1\n`) }
    if c.kind == N_SYS  { emith(`@HE_{c.s} = internal global i32 1\n`) }
    i = i + 1
  }
  # one enabled-flag global per toggled layer (default shown)
  var li = 0
  while li < len(g_toggled_layers) { emith(`@LE_{g_toggled_layers[li]} = internal global i32 1\n`);  li = li + 1 }
}

# L_reset(e): clear every has-flag and the archetype kind for entity e
function emit_ecs_allocator() -> void {
  let me = itoa(MAX_ENT)
  emit("define void @L_reset(i32 %e) {\nentry:\n")
  var i = 0
  while i < len(prog) {
    if prog[i].kind == N_COMP {
      let hn = `%h{itoa(i)}`
      emit("  ");  emit(hn);  emit(" = getelementptr inbounds [");  emit(me);  emit(" x i8], ptr @H_");  emit(prog[i].s);  emit(", i32 0, i32 %e\n")
      emit("  store i8 0, ptr ");  emit(hn);  emit("\n")
    }
    i = i + 1
  }
  emit("  %k = getelementptr inbounds [");  emit(me);  emit(" x i32], ptr @L_kind, i32 0, i32 %e\n")
  emit("  store i32 0, ptr %k\n")
  # N3: reset an @Owned entity's network owner to -1 (unowned) on alloc/free
  if net_has_owned() {
    emit("  %ow = getelementptr inbounds [");  emit(me);  emit(" x i32], ptr @L_owner_arr, i32 0, i32 %e\n")
    emit("  store i32 -1, ptr %ow\n")
  }
  emit("  ret void\n}\n\n")

  emit("define i32 @L_alloc() {\nentry:\n")
  emit("  %fn = load i32, ptr @L_freen\n")
  emit("  %has = icmp sgt i32 %fn, 0\n")
  emit("  br i1 %has, label %reuse, label %fresh\n")
  emit("reuse:\n")
  emit("  %fn1 = sub i32 %fn, 1\n")
  emit("  store i32 %fn1, ptr @L_freen\n")
  emit("  %fp = getelementptr inbounds [");  emit(me);  emit(" x i32], ptr @L_freelist, i32 0, i32 %fn1\n")
  emit("  %re = load i32, ptr %fp\n")
  emit("  br label %done\n")
  emit("fresh:\n")
  emit("  %ec = load i32, ptr @L_entc\n")
  emit("  %ec1 = add i32 %ec, 1\n")
  emit("  store i32 %ec1, ptr @L_entc\n")
  emit("  br label %done\n")
  emit("done:\n")
  emit("  %e = phi i32 [ %re, %reuse ], [ %ec, %fresh ]\n")
  emit("  call void @L_reset(i32 %e)\n")
  emit("  %ap = getelementptr inbounds [");  emit(me);  emit(" x i32], ptr @L_alive, i32 0, i32 %e\n")
  emit("  store i32 1, ptr %ap\n")
  emit("  ret i32 %e\n}\n\n")

  emit("define void @L_free_entity(i32 %e) {\nentry:\n")
  emit("  %ap = getelementptr inbounds [");  emit(me);  emit(" x i32], ptr @L_alive, i32 0, i32 %e\n")
  emit("  store i32 0, ptr %ap\n")
  emit("  call void @L_reset(i32 %e)\n")
  emit("  %fn = load i32, ptr @L_freen\n")
  emit("  %fp = getelementptr inbounds [");  emit(me);  emit(" x i32], ptr @L_freelist, i32 0, i32 %fn\n")
  emit("  store i32 %e, ptr %fp\n")
  emit("  %fn1 = add i32 %fn, 1\n")
  emit("  store i32 %fn1, ptr @L_freen\n")
  emit("  ret void\n}\n\n")
}