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page32.asm
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page32.asm
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; --------------------------------------- Paging routines ---------------------------------------
USE32
InitPageTable32a:
; A more clean version of what we are doing.
; We map the entire 4GB address space (1024*1024*4096) See Through
pushad
push ds
push es
mov ax,data16_idx
push gs
mov gs,ax
mov ebp,[gs:PhysicalPagingOffset32]
pop gs
mov ax,page32_idx
mov ds,ax
mov es,ax
; Tables Clear
mov edi,ebp
mov ecx,2048
xor eax,eax
rep stosd
; PageDir32 points to PageTables32
; Create 1024 entries
mov edi,ebp
xor ecx,ecx
LoopPageDir1:
xor eax,eax
mov eax,ebp
add eax,4096
shr eax,12 ; Get rid of lower 12 bits (4096 alignment)
mov ebx,ecx
add eax,ebx
shl eax,12
or al,7 ; Present, Writable, Everyone,
stosd
inc ecx
cmp ecx,1024
jnz LoopPageDir1
; PageTables32 create 1024 entries
mov edi,ebp
add edi,4096
xor ecx,ecx
LoopPageTables1:
xor eax,eax
mov eax,0 ; See-Through, so we start at 0
add eax,ecx
shl eax,12
or al,7 ; Present, Writable, Everyone,
stosd
inc ecx
cmp ecx,1024
jnz LoopPageTables1
pop es
pop ds
popad
ret
InitPageTable642:
pushad
push ds
push es
mov ax,data16_idx
push gs
mov gs,ax
mov esi,[gs:PhysicalPagingOffset64]
pop gs
mov ax,page64_idx
mov ds,ax
mov es,ax
xor eax, eax
mov edi,esi
mov ecx,03000h
rep stosb
;top level page table
mov eax, esi
add eax,0x1000
or eax,3
mov [esi],eax
mov eax, esi
add eax,0x2000
or eax,3
mov [esi + 0x1000],eax
;2MB pages to identity map the first 16MB ram
mov eax,1
shl eax,7
or eax,3
mov [esi + 0x2000],eax
add eax,0x200000
mov [esi + 0x2008],eax
add eax,0x200000
mov [esi + 0x2010],eax
add eax,0x200000
mov [esi + 0x2018],eax
add eax,0x200000
mov [esi + 0x2020],eax
add eax,0x200000
mov [esi + 0x2028],eax
add eax,0x200000
mov [esi + 0x2030],eax
add eax,0x200000
mov [esi + 0x2038],eax
pop es
pop ds
popad
ret
InitPageTable643:
; a function to use 1GB pages
pushad
push es
push gs
mov ax,data16_idx
mov gs,ax
mov ax,page32_idx
mov es,ax
mov esi,[gs:PhysicalPagingOffset64]
; clear
mov edi,esi
xor eax,eax
mov ecx,03000h
rep stosb
; Put the PML4T to 0x0000, these are 512 entries, so it takes 0x1000 bytes
; We only want the first PML4T
mov eax,esi
add eax,0x1000 ; point it to the first PDPT
or eax,3 ; Present, Readable/Writable
mov [es:esi + 0x0000],eax
mov ecx,4 ; Map 4GB (512*1GB).
mov eax,0x83 ; Also bit 7
mov edi,esi
add edi,0x1000
.lxf1:
mov [es:edi],eax
add eax,1024*1024*1024
add edi,8
loop .lxf1
pop gs
pop es
popad
ret