/*
 *  Support functions for duk_heap.
 */

#include "duk_internal.h"

#if defined(DUK_USE_DOUBLE_LINKED_HEAP) && defined(DUK_USE_REFERENCE_COUNTING)
/* arbitrary remove only works with double linked heap, and is only required by
 * reference counting so far.
 */
DUK_INTERNAL void duk_heap_remove_any_from_heap_allocated(duk_heap *heap, duk_heaphdr *hdr) {
	DUK_ASSERT(DUK_HEAPHDR_GET_TYPE(hdr) != DUK_HTYPE_STRING);

	if (DUK_HEAPHDR_GET_PREV(heap, hdr)) {
		DUK_HEAPHDR_SET_NEXT(heap, DUK_HEAPHDR_GET_PREV(heap, hdr), DUK_HEAPHDR_GET_NEXT(heap, hdr));
	} else {
		heap->heap_allocated = DUK_HEAPHDR_GET_NEXT(heap, hdr);
	}
	if (DUK_HEAPHDR_GET_NEXT(heap, hdr)) {
		DUK_HEAPHDR_SET_PREV(heap, DUK_HEAPHDR_GET_NEXT(heap, hdr), DUK_HEAPHDR_GET_PREV(heap, hdr));
	} else {
		;
	}

	/* The prev/next pointers of the removed duk_heaphdr are left as garbage.
	 * It's up to the caller to ensure they're written before inserting the
	 * object back.
	 */
}
#endif

DUK_INTERNAL void duk_heap_insert_into_heap_allocated(duk_heap *heap, duk_heaphdr *hdr) {
	DUK_ASSERT(DUK_HEAPHDR_GET_TYPE(hdr) != DUK_HTYPE_STRING);

#ifdef DUK_USE_DOUBLE_LINKED_HEAP
	if (heap->heap_allocated) {
		DUK_ASSERT(DUK_HEAPHDR_GET_PREV(heap, heap->heap_allocated) == NULL);
		DUK_HEAPHDR_SET_PREV(heap, heap->heap_allocated, hdr);
	}
	DUK_HEAPHDR_SET_PREV(heap, hdr, NULL);
#endif
	DUK_HEAPHDR_SET_NEXT(heap, hdr, heap->heap_allocated);
	heap->heap_allocated = hdr;
}

#ifdef DUK_USE_INTERRUPT_COUNTER
DUK_INTERNAL void duk_heap_switch_thread(duk_heap *heap, duk_hthread *new_thr) {
	duk_hthread *curr_thr;

	DUK_ASSERT(heap != NULL);

	if (new_thr != NULL) {
		curr_thr = heap->curr_thread;
		if (curr_thr == NULL) {
			/* For initial entry use default value; zero forces an
			 * interrupt before executing the first insturction.
			 */
			DUK_DD(DUK_DDPRINT("switch thread, initial entry, init default interrupt counter"));
			new_thr->interrupt_counter = 0;
			new_thr->interrupt_init = 0;
		} else {
			/* Copy interrupt counter/init value state to new thread (if any).
			 * It's OK for new_thr to be the same as curr_thr.
			 */
#if defined(DUK_USE_DEBUG)
			if (new_thr != curr_thr) {
				DUK_DD(DUK_DDPRINT("switch thread, not initial entry, copy interrupt counter"));
			}
#endif
			new_thr->interrupt_counter = curr_thr->interrupt_counter;
			new_thr->interrupt_init = curr_thr->interrupt_init;
		}
	} else {
		DUK_DD(DUK_DDPRINT("switch thread, new thread is NULL, no interrupt counter changes"));
	}

	heap->curr_thread = new_thr;  /* may be NULL */
}
#endif  /* DUK_USE_INTERRUPT_COUNTER */