real initial commit
This commit is contained in:
Lucia Ceionia
337
entry.nasm
Normal file
337
entry.nasm
Normal file
@@ -0,0 +1,337 @@
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[BITS 16]
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global entry
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entry:
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cli ; no interrupts
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xor ax,ax
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mov ds, ax
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lgdt [gdt_desc] ; load gdt register
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mov eax, cr0 ; set pmode bit
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or al, 1
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mov cr0, eax
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jmp 08h:Pmodecode
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[BITS 32]
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Pmodecode:
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mov ax, 0x10 ; set up segments
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mov ds, ax
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mov es, ax
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mov ss, ax
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mov ebp, 0x400000
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mov esp, ebp
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mov eax, 0x1f001f00
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mov ecx, (80*25)/2
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mov edi, 0xb8000
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rep stosd
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call start
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hlt_loop:
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hlt
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jmp hlt_loop
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setup_paging:
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mov ecx, 1024*3 ; 3K?
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xor eax, eax
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mov edi, 0x1000
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rep stosd ; zero first 3K for some reason
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mov edi, 0x4000
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mov eax, 0x800007 ; 8MB + 7
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std ; fill backwards
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.fill:
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stosd
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sub eax, 0x1000
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jge .fill
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cld ; fix direction
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mov dword [0x0000], 0x2000 + 7
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mov dword [0x0004], 0x3000 + 7
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mov eax, 0x1000
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mov cr3, eax ; page dir start 0x1000
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mov eax, cr0
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or eax, 0x80000000
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mov cr0, eax ; set paging bit
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ret ; flushes pre-fetch queue
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[BITS 16]
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real_hexprint:
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xor cx, cx
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mov bl, al
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shr al, 4
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jmp .donibble
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.nibble2:
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mov al, bl
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inc cx
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.donibble:
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and al, 0x0F
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cmp al, 0x0A
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jl .noadjust
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add al, 'A' - '0' - 10
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.noadjust:
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add al, '0'
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mov ah, 0x1f
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stosw
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test cx, cx
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jz .nibble2
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ret
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real_printword:
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mov dx, ax
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mov al, ah
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call real_hexprint
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mov ax, dx
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call real_hexprint
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ret
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extern v86Code
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v86Code:
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mov ax, 0xb814
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mov es, ax
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mov di, 20
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mov ax, sp
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call real_printword
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add di, 2
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mov ax, ds
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call real_printword
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add di, 2
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mov ax, cs
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call real_printword
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.loop:
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inc byte [0]
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;mov ax, 0x1111
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;mov ds, ax
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;mov ax, 0x2222
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;mov es, ax
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;mov ax, 0x3333
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;mov fs, ax
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;mov ax, 0x4444
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;mov gs, ax
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;mov ax, 0x5555
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;mov ss, ax
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;mov ax, 0x6666
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;mov sp, ax
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int 3
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;jmp .loop
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mov ax, 0x13
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int 0x10
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int 0x30 ; exit
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jmp $
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extern real_test
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real_test:
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nop
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nop
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nop
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jmp $
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[BITS 32]
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; extern void enter_v86(uint32_t ss, uint32_t esp, uint32_t cs, uint32_t eip);
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global enter_v86
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enter_v86:
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mov ebp, esp ; save stack pointer
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push dword [ebp+4] ; ss
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push dword [ebp+8] ; esp
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pushfd ; eflags
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or dword [esp], (1 << 17) ; set VM flags
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;or dword [esp], (3 << 12) ; IOPL 3
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push dword [ebp+12] ; cs
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push dword [ebp+16] ; eip
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iret
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user_test:
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mov dword [0xb8000], 0x0f000f00 | 'U' | 's' << 16
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mov dword [0xb8004], 0x0f000f00 | 'e' | 'r' << 16
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mov dword [0xb8008], 0x0f000f00 | 'm' | 'o' << 16
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mov dword [0xb800C], 0x0f000f00 | 'd' | 'e' << 16
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mov word [0xb8010], 0x0f00 | '!'
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mov edi, 0xA0000
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xor eax, eax
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.loop:
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mov cx, 320
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rep stosb
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inc al
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cmp eax, 200
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jl .loop
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xor ebx, ebx
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div bl
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global jmp_usermode_test
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jmp_usermode_test:
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mov ax, 0x20 | 3
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mov ds, ax
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mov es, ax
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mov fs, ax
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mov gs, ax
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mov eax, esp
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push 0x20 | 3
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push eax
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pushfd
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push 0x18 | 3
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push user_test
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iret
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extern unhandled_handler
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unhandled_handler:
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mov ax, 0x10
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mov ds, ax
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mov dword [0xb8000], 0x0f000f00 | 'E' | 'R' << 16
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mov dword [0xb8004], 0x0f000f00 | 'R' | 'O' << 16
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mov dword [0xb8008], 0x0f000f00 | 'R' | '!' << 16
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.hlt:
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hlt
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jmp .hlt
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extern gpf_handler_v86
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global gpfHandler
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gpfHandler:
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iret
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mov ax, 0x10
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mov ds, ax
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;jmp gpf_handler_v86
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mov word [0xb8000], 0x0f00 | 'G'
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mov word [0xb8002], 0x0f00 | 'P'
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mov word [0xb8004], 0x0f00 | 'F'
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.hlt:
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hlt
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jmp .hlt
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scancodesToAscii: db 0, 0 ; 0x00 - 0x01
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db "1234567890" ; 0x02 - 0x0B
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db "-=" ; 0x0C - 0x0D
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db 0, 0 ; 0x0E - 0x0F
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db "qwertyuiop[]" ; 0x10 - 0x1B
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db 0, 0 ; 0x1C - 0x1D
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db "asdfghjkl;'`" ; 0x1E - 0x29
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db 0 ; 0x2A
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db "\zxcvbnm,./" ; 0x2B - 0x35
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db 0 ; 0x36
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db '*' ; 0x37
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db 0 ; 0x38
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db ' ' ; 0x39
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db 'C'
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scancodesToAsciiEnd:
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cursorCurrent: dd 0xb8000 + (80*6*2)
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global keyboardHandler
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keyboardHandler:
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push eax
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push ebx
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push ds
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mov ax, 0x10
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mov ds, ax
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xor eax, eax
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in al, 0x60
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cmp eax, 0x3A
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jg .done
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mov al, [scancodesToAscii+eax]
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test al, al
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jz .done
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mov ebx, [cursorCurrent]
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mov byte [ebx], al
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add dword [cursorCurrent], 2
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mov byte [KBDWAIT], 1
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.done:
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mov al, 0x20
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out 0x20, al
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pop ds
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pop ebx
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pop eax
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iret
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KBDWAIT: db 0
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global kbd_wait
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kbd_wait:
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mov byte [KBDWAIT], 0
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.loop:
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hlt
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xor eax, eax
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mov al, [KBDWAIT]
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test eax, eax
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jz .loop
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ret
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global timerHandler
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timerHandler:
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push eax
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push ds
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mov ax, 0x10
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mov ds, ax
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inc byte [(0xb8000 + (80*8*2))]
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mov al, 0x20
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out 0x20, al
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pop ds
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pop eax
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iret
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global picInit
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picInit:
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mov al, 0x11 ; initialization sequence
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out 0x20, al ; send to 8259A-1
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jmp $+2
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jmp $+2
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out 0xA0, al ; and to 8259A-2
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jmp $+2
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jmp $+2
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mov al, 0x20 ; start of hardware ints (0x20)
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out 0x21, al
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jmp $+2
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jmp $+2
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mov al, 0x28 ; start of hardware ints 2 (0x28)
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out 0xA1, al
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jmp $+2
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jmp $+2
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mov al, 0x04 ; 8259-1 is master
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out 0x21, al
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jmp $+2
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jmp $+2
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mov al, 0x02 ; 8259-2 is slave
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out 0xA1, al
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jmp $+2
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jmp $+2
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mov al, 0x01 ; 8086 mode for both
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out 0x21, al
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jmp $+2
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jmp $+2
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out 0xA1, al
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jmp $+2
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jmp $+2
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mov al, 0xFF ; all interrupts off for now
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out 0x21, al
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jmp $+2
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jmp $+2
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out 0xA1, al
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ret
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global flushTSS
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flushTSS:
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mov ax, 0x28
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ltr ax
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ret
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extern tss_data
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extern start
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gdt_desc:
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dw gdt_end - gdt
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dd gdt
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gdt:
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gdt_null: dq 0
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gdt_code: dw 0xFFFF, 0 ; bits 0-15 limit (4GB), bits 0-15 base address
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db 0 ; bits 16-23 base address
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db 10011010b ; access byte
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db 11001111b ; bits 16-19 limit (4GB), 4 bits flags
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db 0 ; bits 24-31 base address
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gdt_data: dw 0xFFFF, 0 ; bits 0-15 limit (4GB), bits 0-15 base address
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db 0 ; bits 16-23 base address
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db 10010010b ; access byte
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db 11001111b ; bits 16-19 limit (4GB), 4 bits flags
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db 0 ; bits 24-31 base address
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gdt_r3code: dw 0xFFFF, 0 ; bits 0-15 limit (4GB), bits 0-15 base address
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db 0 ; bits 16-23 base address
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db 0xFA ; access byte
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db 11001111b ; bits 16-19 limit (4GB), 4 bits flags
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db 0 ; bits 24-31 base address
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gdt_r3data: dw 0xFFFF, 0 ; bits 0-15 limit (4GB), bits 0-15 base address
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db 0 ; bits 16-23 base address
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db 0xF2 ; access byte
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db 11001111b ; bits 16-19 limit (4GB), 4 bits flags
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db 0 ; bits 24-31 base address
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gdt_tss: dw 0x2080, 0x0000;26*4, tss_data ; bits 0-15 limit (4GB), bits 0-15 base address
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db 0x2 ; bits 16-23 base address
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db 0x89 ; access byte
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db 00000000b ; bits 16-19 limit (4GB), 4 bits flags
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db 0 ; bits 24-31 base address
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gdt_end:
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