diff options
Diffstat (limited to 'boot2/memmap.asm')
| -rw-r--r-- | boot2/memmap.asm | 57 |
1 files changed, 0 insertions, 57 deletions
diff --git a/boot2/memmap.asm b/boot2/memmap.asm deleted file mode 100644 index d101557..0000000 --- a/boot2/memmap.asm +++ /dev/null @@ -1,57 +0,0 @@ -;--------------------------------------------- -; Get memory map from bios -; /in es:di->destination buffer for entries -; /ret bp=entry count -;--------------------------------------------- - -; stolen from: http://www.brokenthorn.com/Resources/OSDev17.html -struc MemoryMapEntry - .baseAddress resq 1 ; base address of address range - .length resq 1 ; length of address range in bytes - .type resd 1 ; type of address range - .acpi_null resd 1 ; reserved -endstruc - -[bits 16] - -BiosGetMemoryMap: - pushad - xor ebx, ebx - xor bp, bp ; number of entries stored here - mov edx, 'PAMS' ; 'SMAP' - mov eax, 0xe820 - mov ecx, 24 ; memory map entry struct is 24 bytes - int 0x15 ; get first entry - jc .error - cmp eax, 'PAMS' ; bios returns SMAP in eax - jne .error - test ebx, ebx ; if ebx=0 then list is one entry long; bail out - je .error - jmp .start -.next_entry: - mov edx, 'PAMS' ; some bios's trash this register - mov ecx, 24 ; entry is 24 bytes - mov eax, 0xe820 - int 0x15 ; get next entry -.start: - jcxz .skip_entry ; if actual returned bytes is 0, skip entry -.notext: - mov ecx, [es:di + MemoryMapEntry.length] ; get length (low dword) - test ecx, ecx ; if length is 0 skip it - jne short .good_entry - mov ecx, [es:di + MemoryMapEntry.length + 4]; get length (upper dword) - jecxz .skip_entry ; if length is 0 skip it -.good_entry: - inc bp ; increment entry count - add di, 24 ; point di to next entry in buffer -.skip_entry: - cmp ebx, 0 ; if ebx return is 0, list is done - jne .next_entry ; get next entry - jmp .done -.error: - stc -.done: - - mov [MEMMAP_SIZE_OFFSET],bp - popad - ret |