#include <stddef.h>

#include "directxmath/directxmath.h"

//size_t __builtin_wasm_memory_grow(int, size_t);
//size_t __builtin_wasm_memory_size(int);

extern char __heap_base[];
extern char __heap_end[];

static size_t heap_pages = 0;
static size_t alloc_index = 0;

extern "C" {
  size_t mem_size();
  size_t mem_alloc(size_t length);
  size_t node_alloc(int count);

  void node_init_translation(size_t handle, int index, float x, float y, float z);
};

static inline size_t memory_heap_base()
{
  return (size_t)&__heap_base[0];
}

static inline size_t align(size_t n, size_t m)
{
  return (n + (m - 1)) & (~(m - 1));
}

static inline void memory_grow(size_t npages)
{
  __builtin_wasm_memory_grow(0, npages);
}

size_t mem_size()
{
  return __builtin_wasm_memory_size(0);
}

size_t mem_alloc(size_t length)
{
  size_t base = memory_heap_base();

  size_t heap_end = (heap_pages << 16);

  size_t address = alloc_index;

  alloc_index += align(length, 16);

  if (heap_end < alloc_index) {
    size_t npages = align(alloc_index - heap_end, 65536) >> 16;
    memory_grow(npages);
    heap_pages += npages;
  }
  return base + address;
}

size_t node_alloc(int count)
{
  return mem_alloc((sizeof (XMFLOAT4X4)) * count);
}

void node_init_translation(size_t handle, int index, float x, float y, float z)
{
  XMFLOAT4X4 * nodes = reinterpret_cast<XMFLOAT4X4 *>(handle);
  //XMMATRIX XMLoadFloat4x4(&nodes[index]);
  XMMATRIX mat = XMMatrixTranslation(x, y, z);
  XMStoreFloat4x4(&nodes[index], mat);
}