#include "guest_heap.h"
#include <limits.h>

int factorio_guest_heap_init(FactorioGuestHeap *heap, uint8_t *memory,
                             uint64_t memory_size, uint64_t begin, uint64_t end) {
  if (!heap || !memory || !begin || begin > end || end > memory_size ||
      memory_size > SIZE_MAX || begin % 16) return 2;
  *heap = (FactorioGuestHeap){memory, memory_size, begin, begin, end, 0};
  return 0;
}

int factorio_guest_heap_allocate(FactorioGuestHeap *heap, uint64_t size, uint64_t *out) {
  if (!heap || !out || !heap->memory || !heap->begin || heap->begin % 16 ||
      heap->cursor < heap->begin || heap->cursor > heap->end ||
      heap->end > heap->memory_size || heap->memory_size > SIZE_MAX ||
      heap->allocations == UINT_MAX) return 2;
  uint64_t padding = (16 - heap->cursor % 16) % 16;
  if (padding > heap->end - heap->cursor) return 1;
  uint64_t address = heap->cursor + padding;
  if (!size) size = 1; /* operator new(0) still returns a distinct allocation. */
  if (size > heap->end - address) return 1;
  heap->cursor = address + size;
  ++heap->allocations;
  *out = address;
  return 0;
}