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 }