Spasiba, da svidania...

lidt  [idtr]    

         ;=========================================
         ;PROBLEM: Enabling interrupts will cause 
         ;fasm version to tripple fault. 
         ;=========================================


;        sti                            ;enable int's

    

;****************************************************************************
;
;AMDO64 by valy, 2004-2005. Alpha version
;For AMD64 machines (Opteron OK... Athlon 64 ? a priori)
;
;DOS->RM16->PM16->PM64 long mode AND idt64 OK->PM16->RM16->DOS
;1 GB RAM available through paging (easily extensible)
;
;note Win9x does NOT appreciate a "DOS reboot" : u should start only from DOS
;compile with yasm 0.3 : yasm mypgm.asm -fbin -omypgm.com
;launch this demo with a previous "mode con lines=50" to have a real screen,
;can u live with only 25 lines ?
;
;INTERRUPTS DO WORK now, AFTER a short while (cannot figure why)
;
;This source code is FRIENDWARE :
;if u want to use it, mention my name
;if u find some bugs, if SMP is easy to implement, please tell me
;
;****************************************************************************

;****************************************************************************
;
;What's new ? kbd bug solved : actually kbd.handler.dummy must at least
;             make an "in al,60h" else pressing ESC several times may bug
;
;nasm/yasm cannot compile lea rcx,[rcx-something] and error msg is ambiguous :
;code this instead : lea rcx,[dword rcx-something] !!!
;if I make an assembler, the default will be the shorter command 
;****************************************************************************
org 0x100
use16
        jmp Start               ;skip definitions

;from Masm32 to YASM
;%define SHL <<
;%define SHR >>
;%define AND &
;%define use64 [BITS 64]

;======================================
;Real mode code starts from here
;======================================


;************
;section .text
;************
Start:
mainRM16:
        ;--------------------------------
        ;Test CPUID command availability
        ;--------------------------------
        pushfd                          ; save EFLAGS
        pop eax                         ; store EFLAGS in EAX
        mov ebx, eax                    ; save in EBX for later testing
        xor eax, 00200000h              ; toggle bit 21
        push eax                        ; push to stack
        popfd                           ; save changed EAX to EFLAGS
        pushfd                          ; push EFLAGS to TOS
        pop eax                         ; store EFLAGS in EAX
        cmp eax, ebx                    ; see if bit 21 has changed
        jz .no_cpuid                    ; if no change, no CPUID
        jmp cpuid_ok
        
.no_cpuid:
        jmp cpuid_command_not_ok

        ;--------------------------------
        ; Use CPUID to determine if the
        ; processor supports long mode.
        ;--------------------------------
cpuid_ok:

        mov eax, 80000000h              ; Extended-function 8000000h.
        cpuid                           ; Is largest extended function
        cmp eax, 80000000h              ; any function > 80000000h?
        jbe no_long_mode                ; If not, no long mode.
        mov eax, 80000001h              ; Extended-function 8000001h.
        cpuid                           ; Now EDX = extended-features flags.
        bt edx, 29                      ; Test if long mode is supported.
        jnc no_long_mode                ; Exit if not supported.


        cli
        call RM_disable_NMI             ;disable NMI and redirect pics

        push word 2
        popf
        mov ax,fs
        mov [fs_save],ax
        mov ax,gs
        mov [gs_save],ax
        xor ax,ax
        mov fs,ax
        mov gs,ax

        mov dword[mm6_variable], esp  ;movd mm6,esp
        mov esp,0fff0h                  ;SP16

        xor ebx,ebx
        mov bx,cs
        shl ebx,4                       ;ebx is our CS relocation
        mov dword[mm7_variable],ebx      ;movd mm7,ebx

        add [pGDT32+2],ebx
        add [pidt64+2],ebx
        add [jmp_64+2],ebx
        add [jmp64_16+3],ebx
        add [bootcode16+2],ebx
        add [bootdata16+2],ebx
        add [patchidt+4],ebx
        add [patchidt2+4],ebx
        add [bootvideo16+2],dword 0b8000h

        ;build idt64
        pxor mm0,mm0
        mov ecx,63*16
        mov edx,int6463
        add edx,ebx

.idtentry:
        mov eax,edx
        shr eax,16
        mov word[idt64+0+ecx],dx
        mov word[idt64+2+ecx],(bootcode64-gdt)
        mov word[idt64+4+ecx],08E00h    ;1000111000000000b
        mov word[idt64+6+ecx],ax
        movq [idt64+8+ecx],mm0
        sub edx,64                      ;sizeof(int64xx)
        sub ecx,16                      ;sizeof(idt_entry)
        jns .idtentry


        ;enable A20 gate
        ;-----------------
        call  RM_enableA20

        mov ax,0b800h
        mov es,ax
        call RM_init_paging2M

        ;load gdt
        ;----------
        lgdt [pGDT32]

        ;Enable protected mode (CR0.PE=1).
        ;---------------------------------
        
         mov eax,cr0
         or al,1
         mov cr0,eax

        ;Execute a far jump to turn protected mode on.
        ;code16_sel must point to the previously-established 16-bit
        ;code descriptor located in the GDT (for the code currently
        ;being executed).
        ;-----------------------------------------------------------
        
         db 0eah                        ;Far jump...
         dw PMnow
         dw bootcode16-gdt              ;in current code segment.

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;
;At this point we are in 16-bit protected mode,but long
;mode is still disabled.
;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
PMnow:

        ;
        ;Set up the protected-mode stack pointer,SS:ESP.
        ;Stack_sel must point to the previously-established stack
        ;descriptor (read/write data segment),located in the GDT.
        ;----------------------------------------------------------

         mov ax,bootdata16-gdt
         mov ds,ax
         mov ss,ax

         mov ax,bootvideo16-gdt
         mov es,ax
         mov esp,0fff0h                 ;SP16   ;normally esp==SP16 before that

         mov [es:2],dword 'P M '        ;indicate 16 bit protected mode
         mov [es:2+4],dword '1 6 '

         xor eax,eax
         mov cr2,eax

        ;Enable the 64-bit page-translation-table entries by
        ;setting CR4.PAE=1 (this is _required_before activating
        ;long mode).Paging is not enabled until after long mode
        ;is enabled.
        ;------------------------------------------------------

         mov eax,cr4
         bts eax,5                      ;PAE
         bts eax,8                      ;PCE, Perf Counters
         bts eax,9                      ;OSFXSR, Save/Restore of x87/64/128-bit states, enabling XMM too
         mov cr4,eax

        ;
        ;Create the long-mode page tables,and initialize the
        ;64-bit CR3 (page-table base address)to point to the base
        ;of the PML4 page table.The PML4 page table must be located
        ;below 4 Gbytes because only 32 bits of CR3 are loaded when
        ;the processor is not in 64-bit mode.
        ;----------------------------------------------------------

         mov eax,90000h                 ;+SYSPAGEPML4 ;Pointer to PML4 table (<4GB).
         mov cr3,eax                    ;Initialize CR3 with PML4 base.

        ;Enable long mode (set EFER.LME=1).
        ;----------------------------------------------------------
         mov ecx,0c0000080h             ;EFER MSR number.
         rdmsr                          ;Read EFER.
         bts eax,8                      ;Set LME=1.
         wrmsr                          ;Write EFER.

        ;Enable paging to activate long mode (set CR0.PG=1)
        ;----------------------------------------------------------
         mov eax,cr0                    ;Read CR0.
         bts eax,31                     ;Set PE=1.
         mov cr0,eax                    ;Write CR0.
         db 0ebh,0      ;jmp0

        ;At this point,we are in 16-bit compatibility mode
        ;(LMA=1,CS.L=0,CS.D=0 ).
        ;Now,jump to the 64-bit code segment.The offset must be
        ;equal to the linear address of the 64-bit entry point,
        ;because 64-bit code is in an unsegmented address space.
        ;The selector points to the 32/64-bit code selector in the
        ;current GDT.
        ;----------------------------------------------------------

         mov edx,2000000
         mov ebx,0b8000h + 160*15 + 10
         and esp,0fff0h

jmp_64:
         db 066h
         db 0eah
         dd main64
         dw bootcode64-gdt              ;do NOT bother ds,es,ss : cs descriptor is enough
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;
;;
;;;Start of 64-bit code
;;
;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

align 8
use64
main64:                                 ;At this point,we're using 64-bit code

         mov rsp,7FFF0h                 ;SYS_STACK
         db 0ebh,0      ;jmp0

         mov eax,82008h                 ;SYS_SP16 ;not to place just after entering 64-bit mode (else bugs)

         mov ebx,dword[mm6_variable]    ;movd rbx,mm6
         mov [rax],rbx

         mov eax,82000h                 ;SYS_CS16
         mov ebx,dword[mm7_variable]     ;movd rbx,mm7
         mov [rax],rbx

         mov ebx,dword[mm7_variable]     ;movd ebx,mm7
         add ebx,pidt64
patchidt:
         lidt [pidt64]                  ;yasm : DB 0fh,1,1ch,25h,dword
         db 0ebh,0      ;jmp0

         mov byte[82050h],0             ;SYS_SCANCODE
         mov eax,07000700h
         mov [82040h],eax               ;SYS_SCR
         mov [82040h+4],eax             ;SYS_SCR
         mov [82040h+8],eax             ;SYS_SCR
         mov [82040h+12],eax            ;SYS_SCR


        ;clear text screen
        ;------------------

         call LM_Clear_screen

         ;=========================================
         ;PROBLEM: Enabling interrupts will cause 
         ;fasm version to tripple fault. 
         ;=========================================

;        sti                            ;enable int's


         ;test timer/kbd interrupt : wait an ESC key
         ;-------------------------------------------
         mov byte[82050h],0                     ;SYS_SCANCODE


.wait_esc:
         call LM_show_action
         mov al,byte[82050h]                    ;SYS_SCANCODE
         push rdi
         mov edi,0b8000h+20                     ;show scancode on screen.
         mov [edi],al                           ;show scancode on screen.
         pop rdi
         cmp al,81h                             ;SYS_SCANCODE


         jne .wait_esc

         ;kill timer/kbd interrupt
         cli
         mov ebx,[82000h]                       ;SYS_CS16
         mov edx,ebx
         add edx,timer_handler_dummy
         mov eax,edx
         shr eax,16
         mov word[ebx+idt64+0+(32*16)],dx
         mov word[ebx+idt64+6+(32*16)],ax

         mov ebx,[82000h]                       ;SYS_CS16
         mov edx,ebx
         add edx,kbd_handler_dummy
         mov eax,edx
         shr eax,16
         mov word[ebx+idt64+0+(33*16)],dx
         mov word[ebx+idt64+6+(33*16)],ax

         mov ebx,[82000h]                       ;SYS_CS16
         add ebx,pidt64
patchidt2:
         lidt [pidt64]                          ;yasm : DB 0fh,1,1ch,25h,dword
         db 0ebh,0      ;jmp0
         sti

         ;test dummy isr functions with
         ;the patched IDT64
         ;--------------------------------------------
         mov edx,1000000000
.wait:
         dec edx
         jnz .wait
         cli


        ;return to PM16
        ;------------------
gobacktoPM16:
         movd mm6,[82008h]              ;SYS_SP16
         movd mm7,[82000h]              ;SYS_CS16
jmp64_16:
         db 0ffh,2ch,25h
         dd jmpmem

use16
PM64Z:

         mov esp,0fff0h                 ;SP16
         mov ax,bootdata16-gdt          ;necessary to successfully go back to RM !!
         mov ds,ax
         mov es,ax
         mov ss,ax

        ;disable paging
        ;--------------
         mov eax,cr0                    ;Read CR0.
         btr eax,31                     ;Set PE=0.
         mov cr0,eax                    ;Write CR0.
         db 0ebh,0      ;jmp0

        ;disable LME
        ;--------------
         mov ecx,0c0000080h             ;EFER MSR number.
         rdmsr                          ;Read EFER.
         btr eax,8                      ;Set LME=0.
         wrmsr                          ;Write EFER.
         db 0ebh,0      ;jmp0

        ;leave PM
        ;--------------
         mov eax,cr0
         and al,0feh
         mov cr0,eax
         db 0ebh,0      ;jmp0

         mov eax,dword[mm7_variable] ;movd eax,mm7
         shr eax,4
         push ax
         push word RM16
         retf

RM16:
         mov ds,ax
         mov ss,ax
         mov ax,0b800h
         mov es,ax
         mov [es:5*160],dword 'E N '
         mov [es:5*160+4],dword 'D ! '
         mov esp,dword[mm6_variable]  ;movd esp,mm6

         mov word[pIDT16.limit],03ffh
         mov dword[pIDT16.base],0
         mov ax,[fs_save]
         mov fs,ax
         mov ax,[gs_save]
         mov gs,ax

         lidt [pIDT16]

;RESTORE NMI
         ;/* setup PIC */
         mov bl,8
         mov bh,0x70
         call RM_pic_setup

         ;/* restore IRQ masks */
         mov al,byte [old_IRQ_mask]
         out 0x20+1,al
         mov al,byte [old_IRQ_mask+1]
         out 0xA0+1,al

         sti

        jmp theend      ;skip long mode not detected complaint.

        ;============================================
        ;Handle cases where cpuid command is not 
        ;supported.
        ;============================================

cpuid_command_not_ok:

         push es
         mov ax,0b800h
         mov es,ax
         mov [es:0]     ,dword 'N O '   ;hardcoded error message! 
         mov [es:4]     ,dword '  C '
         mov [es:8]     ,dword 'P U '
         mov [es:12]    ,dword 'I D '
         mov [es:16]    ,dword '  S '
         mov [es:20]    ,dword 'U P '
         mov [es:24]    ,dword 'P O '
         mov [es:28]    ,dword 'R T '
         mov [es:32]    ,dword 'E D '
         mov [es:32]    ,dword '!  '
         pop es

        jmp theend
        ;=============================================
        ;Handle cases where long mode is not detected.
        ;=============================================

no_long_mode:

         push es
         mov ax,0b800h
         mov es,ax
         mov [es:0]     ,dword 'N O '   ;hardcoded error message! 
         mov [es:4]     ,dword '  L '
         mov [es:8]     ,dword 'O N '
         mov [es:12]    ,dword 'G M '
         mov [es:16]    ,dword 'O D '
         mov [es:20]    ,dword 'E   '
         mov [es:24]    ,dword 'F O '
         mov [es:28]    ,dword 'U N '
         mov [es:32]    ,dword 'D ! '
         pop es

        jmp theend

        
        ;********************
        ;The end
        ;********************
theend:
        
        mov ah,0                ;wait a key
        int 0x16

        mov ax,3                ;set vga text mode
        int 0x10
 
        mov     ax,0x4C00
        int     21h

;       ret


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
use16

;messages
;---------

long_mode_detected_msg db 13,10,'Long mode detected!',0


;*************************************************************************
;RM_disable_NMI: Disables non-maskable ints and redirect pics
;
;input:  --
;output: --
;*************************************************************************

RM_disable_NMI:
        ;DISABLE NMI to enter 64-bit mode later

        ;save IRQ masks
        ;--------------------
        in al,0x20+1
        mov byte [old_IRQ_mask],al
        in al,0xA0+1
        mov byte [old_IRQ_mask+1],al

        ;setup PIC to redirect external
        ;interrupts to range 32-47
        ;-------------------------------
        mov bl,0x21
        mov bh,0x29
        call RM_pic_setup               ;(0x20, 0x28);

        ;/* set new IRQ masks */
        mov al,0xfc                     ;1st bit is for timer, 2nd for keyboard (master)
        out 0x20+1,al
        mov al,0xff
        out 0xA0+1,al                   ;/* disable all (slave) */

        ret                             ;end of procedure


;*************************************************************************
; RM_pic_setup: redirects pics
;
;input: bl=master vector,bh=slave vector
;
;output: --
;*************************************************************************

RM_pic_setup:
          mov al,0x11
          out 0x20,al                   ;start 8259 initialization 
          out 0xA0,al
          mov al,bl ;master_vector      ;master base interrupt vector
          out 0x20+1,al
          mov al,bh ;slave_vector       ;slave base interrupt vector
          out 0xA0+1,al
          mov al,4 ;1<<2                ;bitmask for cascade on IRQ2
          out 0x20+1,al
          mov al,2
          out 0xA0+1,al                 ;cascade on IRQ2
          mov al,1
          out 0x20+1,al                 ;finish 8259 initialization
          out 0xA0+1,al
          ret                           ;end of procedure

;*************************************************************************
; RM_enableA20: Enables A20 gate.
;
;input: --
;
;output: --
;*************************************************************************


RM_enableA20:
        call    enablea201
        jnz     enablea20done
        mov     al,0d1h
        out     64h,al
        call    enablea201
        jnz     enablea20done
        mov     al,0dfh
        out     60h,al
enablea201:
        mov     ecx,20000h
enablea201l:
        jmp     $+2       ;short $+2
        in      al,64h
        test    al,2
        loopnz  enablea201l
enablea20done:
          ret                           ;end of procedure

;*************************************************************************
; RM_init_paging2M: Creates memory page table for long mode.
;
;input: --
;
;output: --
;*************************************************************************

RM_init_paging2M:                       ;here, 512*2 MB bytes = 1 GB
         mov ax,ds
         push ax                        ;!!! NO push cs !!!

         mov ax,9000h
         mov ds,ax

         xor eax,eax
         mov ecx,2048
         pxor mm0,mm0
         xor esi,esi
.init_paging2M0:
         movq [ds:esi],mm0
         add esi,8
         dec ecx
         jnz .init_paging2M0

        ;PML4/PDPE/PDE
         mov [ds:0],dword 90000h + 4096+15
         mov [ds:4096],dword 90000h + 8192 +15
        ;PDE
         xor esi,esi
         mov ecx,15+128                 ;128==PDE.PS
         mov eax,1 SHL 21               ;2097152

.init_paging2M1:
         mov [ds:8192+esi],ecx
         add ecx,eax
         add esi,8
         cmp esi,8*512                  ;we paginate 512*2 MB bytes
         jne .init_paging2M1

         pop ax
         mov ds,ax
         ret


;*************************************************************************
; RM_DisplayMessage: Displays ASCIIZ string at ds:si via BIOS
;
;input: ds:si ASCIIZ string pointer
;
;output: --
;*************************************************************************
RM_DisplayMessage:


        lodsb                                       ; load next character
        or      al, al                              ; test for NUL character
        jz      RM_DisplayMessage.done
        mov     ah, 0x0E                            ; BIOS teletype
        mov     bh, 0x00                            ; display page 0
        mov     bl, 0x07                            ; text attribute
        int     0x10                                ; invoke BIOS
        jmp     RM_DisplayMessage

.done:
        ret             ; end of procedure



use64

;*************************************************************************
;LM_show_action: show some action on text srceen
;
;input:  --
;output: --
;*************************************************************************

align 4
LM_show_action:
         push rax
         push rdi
         mov edi,0b8000h+30             ;show '!' character
         mov byte[edi], '!'
         inc edi
         inc byte[edi]                  ;update color
         pop rdi
         pop rax
         ret                            ;end of procedure


;********************************************************************
;
; IRQ0 = Default handler for timer. Incoming byte is read from
;        the port but nothing else is done.
;
;
;********************************************************************
align 16

timer_handler_dummy:
        push rax
        mov al,0x20                     ;send end of interrupt command
        out 0x20,al
        pop rax
        iretq

;********************************************************************
;
; IRQ1 = Default handler for keyboard. Incoming byte is read from
;        the port but nothing else is done.
;
;
;********************************************************************
align 16

kbd_handler_dummy:
        push rax
        in al,60h
        mov al,0x20                     ;send end of interrupt command
        out 0x20,al
        pop rax
        iretq


use64
;********************************************************************
;
; IRQ0 = Handler for timer. Text screen word is increased by one when
;       timer interrupt occures.                
;
;
;********************************************************************
align 16

timer_handler:
        push rax
        inc word[0b8000h+40]            ;indicate timer handler activity
        mov al,0x20                     ;send end of interrupt command
        out 0x20,al
        pop rax
        ret


use64
;********************************************************************
;
; IRQ1 = Handler for keyboard. Incoming byte is read from
;        the port and stored into memory location.
;
;
;********************************************************************
align 16

kbd_handler:
        push rax
        in al,0x60
        mov [82050h],al                 ;SYS_SCANCODE
        mov al,0x20                     ;send end of interrupt command
        out 0x20,al
        pop rax
        ret

use64

;*************************************************************************
;LM_Clear_screen: Clears text screen
;
;input:  --
;output: --
;*************************************************************************

align 4
LM_Clear_screen:
         mov edi,0b8000h
         movaps xmm0,[82040h]           ;SYS_SCR

.loop:
         movaps [edi],xmm0
         add edi,16
         cmp edi,0b8000h+50*160
         jl .loop
         ret                            ;end of procedure

;=============
;YASM variant
;=============
use64
; %macro myint 1;{
;       int64%1:
;
;        ;;;cli
;
;        mov ebx,%1
;        cmp ebx,32
;        jl .reboot
;
;.noreboot:
;        cmp ebx,20h
;        jne .timer_handlerz            ;short .skip
;        call timer_handler
;.timer_handlerz:
;        cmp ebx,21h
;        jne .kbd_handlerz              ;short .skip
;        call kbd_handler
;.kbd_handlerz:
;
;
;.skip:
;        mov al,0x20
;        out 0x20,al                    ;send end of interrupt command
;        ;;;sti
;        iretq
;
;.reboot:
;        cli;;;
;        jmp gobacktoPM16
;
;       int64z%1:
;        times (64-int64z%1+int64%1) db 0
;       %endmacro

;=============
;FASM variant
;=============
use64

macro myint Number {
        int64#Number:

         ;;;cli

         mov ebx,#Number
         cmp ebx,32
         jl .reboot

.noreboot:
         cmp ebx,20h
         jne .timer_handlerz            ;short .skip
         call timer_handler
.timer_handlerz:
         cmp ebx,21h
         jne .kbd_handlerz              ;short .skip
         call kbd_handler
.kbd_handlerz:


.skip:
         mov al,0x20
         out 0x20,al                    ;send end of interrupt command
         ;;;sti
         iretq

.reboot:
         cli;;;

         jmp gobacktoPM16
        int64z#Number:
         times (64-int64z#Number+int64#Number) db 0
        };%endmacro

;-------------------------
;create interrupt handlers
;-------------------------
align 16

        myint 0
        myint 1
        myint 2
        myint 3
        myint 4
        myint 5
        myint 6
        myint 7
        myint 8
        myint 9
        myint 10
        myint 11
        myint 12
        myint 13
        myint 14
        myint 15
        myint 16
        myint 17
        myint 18
        myint 19
        myint 20
        myint 21
        myint 22
        myint 23
        myint 24
        myint 25
        myint 26
        myint 27
        myint 28
        myint 29
        myint 30
        myint 31
        myint 32
        myint 33
        myint 34
        myint 35
        myint 36
        myint 37
        myint 38
        myint 39
        myint 40
        myint 41
        myint 42
        myint 43
        myint 44
        myint 45
        myint 46
        myint 47
        myint 48
        myint 49
        myint 50
        myint 51
        myint 52
        myint 53
        myint 54
        myint 55
        myint 56
        myint 57
        myint 58
        myint 59
        myint 60
        myint 61
        myint 62
        myint 63

use64

;************
;section .data
;************
align 16

;==========================
; Global descriptor table
;==========================
mydata:
pGDT32:
         dw gdtend-gdt  ;gdt32_limit ;GDT limit ...
         dd gdt         ;gdt32_base ;and 32-bit GDT base
         dd 0
pGDT64:                 ;label tbyte ;Used by LGDT.
         dw gdtend-gdt  ;GDT limit ...
         dq gdt         ;and 64-bit GDT base

align 8
gdt:     dd 0,0         ;null descriptor
gdtCS16:
bootcode16:
         dd 0ffffh
         dd 09b00h
bootdata16:
         dd 0ffffh
         dd 09300h
bootvideo16:
         dd 0ffffh
         dd 09300h
gdtCS64:
bootcode64:
         dd 0ffffh
         dd 0af9b00h
gdtend:

;============================
; Interrupt descriptor table
;============================
pidt64:
                dw idt64end-1-idt64             ;idt_limit
                dd idt64                        ;idt_base to be patched : linear address
                dd 0

align 16
idt64:
                ;low offset,code selector,std values,medium offset,high offset,highest offset,0,0
                times 64 dw 0,bootcode64-gdt,8E00h,0,0,0,0,0
idt64end:

jmpmem:
                dw PM64Z
                dw 0
                dw bootcode16-gdt

align 16
mystack:        dq 0,0,0,0,0,0,0,0

pIDT16:
.limit:         dw 03ffh        ;idt_limit
.base:          dd 0            ;idt_base

fs_save:        dw 0
gs_save:        dw 0

old_IRQ_mask:   db 0,0
irqmask:        db 0,0

mm6_variable:   dd 0       ;just for debugging purposes (Fasm doesn't accept some movd variants. We need to use variables instead.)
mm7_variable:   dd 0       ;just for debugging purposes


    

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
MakePages32:

PML432_start                    equ     0x1000
PDPTE32_start                   equ     0x2000
PDE32_start                     equ     0x3000

; clear possible crab, for reserved bits and clean addresses
mov cx,2048*3           ; 2048byte * word = 4096byte a page * 3
mov di,PML432_start
clearPages:
mov word [es:di],0
add di,2
dec cx
jnz clearPages

mov cx,16
mov di,PML432_start

fillPML432:
mov word [es:di],PDPTE32_start + 3      ; + Page Type
add di,8
dec cx
jnz fillPML432

;blz.114 4 * PDPTE Page-Directory-Pointer-Table-Entries * 512 PDE Page-Directory-Entries
;blz.118 format of PDPTE / PDE
mov cx,4
mov di,PDPTE32_start

fillPDPTE32:
mov word [es:di],PDE32_start + 3        ; + Page Type
add di,8
dec cx
jnz fillPDPTE32

mov cx,512
mov di,PDE32_start
fillPDE32:
;                5432109876543210
mov word [es:di],0000000010000011b      ; Page Type
mov word [es:di + 2],0
add ax,word 100000b
add di,8
dec cx
jnz fillPDE32
        
ret