consts

// vi:set ft=cpp: -*- Mode: C++ -*-
 
#pragma once
 
#include <l4/sys/consts.h>
 
namespace L4 {
 
  template<typename T>
  constexpr T trunc_order(T val, unsigned char order)
  {
    return val & ((~T(0)) << order);
  }
 
  template<typename T>
  constexpr T round_order(T val, unsigned char order)
  {
    return (val + (T(1) << order) - T(1)) & ((~T(0)) << order);
  }
 
  template<typename T>
  constexpr T trunc_page(T val)
  {
    return trunc_order(val, L4_PAGESHIFT);
  }
 
  template<typename T>
  constexpr T round_page(T val)
  {
    return round_order(val, L4_PAGESHIFT);
  }
 
  template<typename T>
  inline unsigned char
  max_order(unsigned char order, T addr,
           T min_addr, T max_addr,
           T hotspot = T(0))
  {
    while (order < 30 /* limit to 1GB flexpages */)
      {
        T mask;
        T base = trunc_order(addr, order + 1);
        if (base < min_addr)
          return order;
 
        if (base + (T(1) << (order + 1)) - T(1) > max_addr - T(1))
          return order;
 
        mask = ~((~T(0)) << (order + 1));
        if (hotspot == ~T(0) || ((addr ^ hotspot) & mask))
          break;
 
        ++order;
      }
 
    return order;
  }
 
}