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