// Copyright 2019 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

//
//
//

#include <stdlib.h>

//
//
//

#include "common/macros.h"
#include "find_mem_type_idx.h"

//
//
//

static uint32_t
vk_spn_ffs(uint32_t * lsb, uint32_t const mask)
{
#ifdef _MSC_VER
  return _BitScanForward((unsigned long *)lsb, mask);  // returns 0 or 1
#else
  uint32_t const lsb_plus_1 = __builtin_ffs(mask);

  *lsb = lsb_plus_1 - 1;

  return lsb_plus_1;  // returns [0,32]
#endif
}

//
//
//

uint32_t
vk_find_mem_type_idx(VkPhysicalDeviceMemoryProperties const * pdmp,
                     uint32_t                                 memoryTypeBits,
                     VkMemoryPropertyFlags const              mpf)
{
  //
  // FIXME -- jump between indices in the memoryTypeBits mask
  //
  uint32_t lsb;

  while (vk_spn_ffs(&lsb, memoryTypeBits) != 0)
    {
      // clear this bit
      memoryTypeBits ^= (1u << lsb);

      // otherwise, find first match...
      VkMemoryPropertyFlags const common = pdmp->memoryTypes[lsb].propertyFlags & mpf;

      if (common == mpf)
        {
          return lsb;
        }
    }

  return UINT32_MAX;
}

//
//
//