L4Re Operating System Framework – Interface and Usage Documentation
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consts
1// vi:set ft=cpp: -*- Mode: C++ -*-
2
3#pragma once
4
5#include <l4/sys/consts.h>
6
7namespace L4 {
8
17 template<typename T>
18 constexpr T trunc_order(T val, unsigned char order)
19 {
20 return val & ((~T(0)) << order);
21 }
22
31 template<typename T>
32 constexpr T round_order(T val, unsigned char order)
33 {
34 return (val + (T(1) << order) - T(1)) & ((~T(0)) << order);
35 }
36
37 template<typename T>
38 constexpr T trunc_page(T val)
39 {
40 return trunc_order(val, L4_PAGESHIFT);
41 }
42
43 template<typename T>
44 constexpr T round_page(T val)
45 {
46 return round_order(val, L4_PAGESHIFT);
47 }
48
49 template<typename T>
50 inline unsigned char
51 max_order(unsigned char order, T addr,
52 T min_addr, T max_addr,
53 T hotspot = T(0))
54 {
55 while (order < 30 /* limit to 1GB flexpages */)
56 {
57 T mask;
58 T base = trunc_order(addr, order + 1);
59 if (base < min_addr)
60 return order;
61
62 if (base + (T(1) << (order + 1)) - T(1) > max_addr - T(1))
63 return order;
64
65 mask = ~((~T(0)) << (order + 1));
66 if (hotspot == ~T(0) || ((addr ^ hotspot) & mask))
67 break;
68
69 ++order;
70 }
71
72 return order;
73 }
74
75}
#define L4_PAGESHIFT
Size of a page, log2-based.
Definition consts.h:37
L4 low-level kernel interface.
constexpr T round_order(T val, unsigned char order)
Round a value up so the given number of lsb is zero.
Definition consts:32
constexpr T trunc_order(T val, unsigned char order)
Round a value down so the given number of lsb is zero.
Definition consts:18