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comparison mem.c @ 1:42ba76f77035 default tip

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the kernel with output and mem alloc
author meillo@marmaro.de
date Sun, 01 Nov 2009 23:50:51 +0100
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0:99db6262c157 1:42ba76f77035
1 #include "mem.h"
2 #include "io.h"
3
4
5 void
6 initmem(unsigned int memstart)
7 {
8 unsigned int* p;
9 int step = 2*1024*1024;
10 unsigned int* zero = 0x0;
11
12
13 minmem = (unsigned char*)memstart;
14
15 /* disable cache */
16 __asm__ __volatile__ (
17 "movl %cr0, %eax\n\t"
18 "movl $0x60000000, %ebx\n\t"
19 "orl %ebx, %eax\n\t"
20 "movl %eax, %cr0"
21 );
22
23 /* test mem size */
24 p = (unsigned int*) ((unsigned int)minmem/sizeof(char));
25 do {
26 p += step;
27 *p = 0xf0f0f0f0;
28 } while (*p == 0xf0f0f0f0);
29 maxmem = (unsigned char*)p;
30
31 /* test mem mirroring */
32 p = 0;
33 *p = 0;
34 p++;
35 while (p < (unsigned int*)minmem) {
36 p = (unsigned int*) ((unsigned int)p * 2);
37 }
38 while (p < (unsigned int*)maxmem) {
39 *p = 0xf0f0f0f0;
40 if (*zero == 0xf0f0f0f0) {
41 maxmem = (unsigned char*)p;
42 break;
43 }
44 p = (unsigned int*) ((unsigned int)p * 2);
45 }
46
47 /* enable cache again */
48 __asm__ __volatile__ (
49 "movl %cr0, %eax\n\t"
50 "movl $0x60000000, %ebx \n\t"
51 "negl %ebx\n\t"
52 "andl %ebx, %eax\n\t"
53 "movl %eax, %cr0"
54 );
55
56 /* min, max */
57 printf("mem: start=%p end=%p size=%p\n", minmem, maxmem, (void*)(maxmem-minmem));
58
59 /* init heap */
60 newp = minmem;
61 }
62
63
64 void*
65 malloc(unsigned int size)
66 {
67 if (newp + size > maxmem) {
68 printf("Fatal error: memory exhausted!\n");
69 while (1) {
70 }
71 }
72 newp += size;
73 return newp - size;
74 }