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comparison cos/kernel/mm.c @ 26:dcce92b1efbc

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Added mm.c
author windel
date Tue, 27 Dec 2011 17:36:52 +0100
parents
children 47b7df514243
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25:d3c4bf3720a3 26:dcce92b1efbc
1
2 /* Memory manager */
3
4 #include "kernel.h"
5
6 // BITMAP functions:
7 #define NFRAMES 1000
8 // Bit mask to check what frames are in use and which are free:
9 uint64_t frames[NFRAMES]; // NFRAMES*64*4kB frames.
10
11 void set_frame(uint64_t frame)
12 {
13 uint64_t idx = frame / 64;
14 uint64_t off = frame % 64;
15 frames[idx] |= (0x1 << off);
16 }
17
18 void clear_frame(uint64_t frame)
19 {
20 uint64_t idx = frame / 64;
21 uint64_t off = frame % 64;
22 frames[idx] &= ~(0x1 << off);
23 }
24
25 uint64_t test_frame(uint64_t frame)
26 {
27 uint64_t idx = frame / 64;
28 uint64_t off = frame % 64;
29 return (frames[idx] & (0x1 << off));
30 }
31
32 uint64_t first_frame()
33 {
34 uint64_t i, j;
35 for (i = 0; i < NFRAMES / 64; i++)
36 {
37 if (frames[i] != 0xFFFFFFFFFFFFFFFF)
38 {
39 for (j = 0; j < 64; j++)
40 {
41 uint64_t dut = 0x1 << j;
42 if ((frames[i] & dut) != dut)
43 {
44 return i*64+j;
45 }
46 }
47 }
48 }
49 return 0xFFFFFFFFFFFFFFFF;
50 }
51
52 // Memory manager functions:
53 void alloc_frame()
54 {
55 uint64_t idx = first_frame();
56 if (idx == (uint64_t) -1)
57 {
58 panic("No more memory!");
59 }
60 set_frame(idx);
61 }
62
63