diff options
| author | Lizzy Fleckenstein <eliasfleckenstein@web.de> | 2022-10-06 16:45:17 +0200 |
|---|---|---|
| committer | Lizzy Fleckenstein <eliasfleckenstein@web.de> | 2022-10-06 16:45:17 +0200 |
| commit | f8397815545adb7d0da36614e0065aa68453a2e4 (patch) | |
| tree | a771f526970c6724b2511577dceece8783450a49 /stage2/mmap.asm | |
| download | cuddles-f8397815545adb7d0da36614e0065aa68453a2e4.tar.xz | |
Initial commit
Diffstat (limited to 'stage2/mmap.asm')
| -rw-r--r-- | stage2/mmap.asm | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/stage2/mmap.asm b/stage2/mmap.asm new file mode 100644 index 0000000..b5cbe79 --- /dev/null +++ b/stage2/mmap.asm @@ -0,0 +1,56 @@ +%define MAPMAGIC 0x534D4150 + +mmap: + mov ebx, .msg + call print_str + + xor ebx, ebx ; counter for interrupt + mov di, MEMMAP + +.loop: + ; issue an INT 0x15, EAX = 0xE820 interrupt + mov eax, 0xE820 + mov ecx, 24 + mov edx, MAPMAGIC + int 0x15 + + cmp eax, MAPMAGIC ; detect failure + jne .fail + + cmp dword[di+16], 1 + jne .next + + cmp dword[di+4], 0 + jne .keep + + cmp dword[di+0], 0x100000 + jb .next + +.keep: + mov dword[di+20], 0 + add di, 24 + +.next: + cmp ebx, 0 + jne .loop + + mov dword[di+0], 0 + mov dword[di+4], 0 + + ;mov ax, di + ;sub ax, MEMMAP + ;xor dx, dx + ;mov bx, 24 + ;div bx + ;mov [MEMMAPCNT], ax + + ret + +.fail: + mov ebx, .fail_msg + call print_str + jmp $ + +.msg: db "getting extended memory map", 10, 13, 0 +.fail_msg: db "memory map failure", 10, 13, 0 + |