minor stuff with the A20 line '-'
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@ -0,0 +1,10 @@
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//----------------------------------------------------------------------------//
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// GNU GPL OS/K //
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// //
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// Authors: spectral` //
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// NeoX //
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// //
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// Desc: ELF64 Parser and Loader //
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//----------------------------------------------------------------------------//
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@ -33,13 +33,6 @@
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%define volumeLabel bp+0x2b ; Volume Label
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%define fatTypeLabel bp+0x36 ; File system type
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;; DISK BUFFER "SEGMENT"
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%define BUFFER_SEG 0x07c0 ; (BUFFER_SEG << 4) + BUFFER_OFF = 0x07C00
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%define BUFFER_OFF 0x0000
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;; SECOND STAGE LOADER "SEGMENT"
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%define LOAD_SEG LONG_SELECTOR-GDT64 ; (LOAD_SEG << 4) + LOAD_OFF = 0x070000
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%define LOAD_OFF Kernel
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[BITS 16]
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@ -56,13 +49,13 @@ jmp 0x0000:main
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;; GDT WITH DOC
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GDT64:
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NULL_SELECTOR: ;; null selector within 64 bits
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dw GDT_LENGTH ; limit of GDT
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dw GDT64 ; linear address of GDT
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dd 0x0 ;
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dw GDT_LENGTH ; limit of GDT
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dw GDT64 ; linear address of GDT
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dd 0x0 ;
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CODE_SELECTOR: ;; 32-bit code selector (ring 0)
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dw 0x0FFFF ; Segment Limit
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db 0x0, 0x0, 0x0 ; Base Address
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dw 0x0000FFFF ; Segment Limit
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db 0x0, 0x0, 0x0 ; Base Address
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db 10011010b ; |7|6|5|4|3|2|1|0|
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; | | | | | | | `----- 1 when segment used.
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; | | | | | | `------ 1 when writable.
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@ -72,7 +65,7 @@ GDT64:
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; | | `---------- DPL !!! 0 for ring 0
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; | `----------- DPL (2/2)
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; `------------ 1 if in physical memory, 0 if page fault
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db 11001111b ; |7|6|5|4|3|2|1|0|
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db 11001111b ; |7|6|5|4|3|2|1|0|
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; | | | | | | | `----- Limit 16
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; | | | | | | `------ Limit 17
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; | | | | | `------- Limit 18
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@ -81,11 +74,11 @@ GDT64:
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; | | `---------- 0 always
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; | `----------- size of data. 1 for 32bits
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; `------------ 0 if limit is in Bytes, 1 if it's in pages (4ko)
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db 0x0 ; Base Address
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db 0x0 ; Base Address
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DATA_SELECTOR: ;; flat data selector (ring 0)
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dw 0x0FFFF ; Segment Limit
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db 0x0, 0x0, 0x0 ; Base Address
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dw 0x0000FFFF ; Segment Limit
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db 0x0, 0x0, 0x0 ; Base Address
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db 10010010b ; |7|6|5|4|3|2|1|0|
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; | | | | | | | `----- 1 when segment used.
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; | | | | | | `------ 1 when writable.
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@ -95,7 +88,7 @@ GDT64:
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; | | `---------- DPL !!! 0 for ring 0
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; | `----------- DPL (2/2)
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; `------------ 1 if in physical memory, 0 if page fault
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db 10001111b ; |7|6|5|4|3|2|1|0|
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db 10001111b ; |7|6|5|4|3|2|1|0|
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; | | | | | | | `----- Limit 16
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; | | | | | | `------ Limit 17
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; | | | | | `------- Limit 18
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@ -104,11 +97,11 @@ GDT64:
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; | | `---------- 0 always
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; | `----------- size of data. 1 for 32bits
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; `------------ 0 if limit is in Bytes, 1 if it's in pages (4ko)
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db 0x0 ; Base Address
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db 0x0 ; Base Address
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LONG_SELECTOR: ;; 64-bit code selector (ring 0)
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dw 0x0FFFF ; Segment Limit
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db 0x0, 0x0, 0x0 ; Base Address
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dw 0x0000FFFF ; Segment Limit
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db 0x0, 0x0, 0x0 ; Base Address
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db 10011010b ; |7|6|5|4|3|2|1|0|
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; | | | | | | | `----- 1 when segment used.
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; | | | | | | `------ 1 when writable.
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@ -118,7 +111,7 @@ GDT64:
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; | | `---------- DPL !!! 0 for ring 0
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; | `----------- DPL (2/2)
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; `------------ 1 if in physical memory, 0 if page fault
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db 10101111b ; |7|6|5|4|3|2|1|0|
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db 10101111b ; |7|6|5|4|3|2|1|0|
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; | | | | | | | `----- Limit 16
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; | | | | | | `------ Limit 17
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; | | | | | `------- Limit 18
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@ -127,7 +120,7 @@ GDT64:
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; | | `---------- 0 always
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; | `----------- size of data. 1 for 32bits
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; `------------ 0 if limit is in Bytes, 1 if it's in pages (4ko)
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db 0x0 ; Base Address
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db 0x0 ; Base Address
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GDT_LENGTH:
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%include "boot/loader16.inc"
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@ -195,6 +188,21 @@ main32:
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pop dword [VGA_HEIGHT32]
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pop dword [VIDEO_MODE32]
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;; VERIFY A20
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pushad
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mov edi,0x112345 ;odd megabyte address.
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mov esi,0x012345 ;even megabyte address.
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mov [esi],esi ;making sure that both addresses contain diffrent values.
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mov [edi],edi ;(if A20 line is cleared the two pointers would point to the address 0x012345 that would contain 0x112345 (edi))
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cmpsd ;compare addresses to see if the're equivalent.
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popad
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jne .A20_on ;if not equivalent , A20 line is set.
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mov WORD [A20_OK], 0
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jmp .A20_end
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.A20_on:
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mov BYTE [A20_OK], 1
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.A20_end:
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;; INITIALIZE PROTECTED MODE SEGMENT REGISTERS
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mov ax, DATA_SELECTOR-GDT64
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mov ds, ax
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@ -260,6 +268,7 @@ KernSearch db 0x09, " Loading the Kernel in RAM...", 0
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txt db 0x09, " Switching to Long Mode... ", 0
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Reinit db "Booting OS/K !", 0x0D, 0x0A, 0x0D, 0x0A, 0
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Pass db " OK", 0x0A, 0x0D, 0
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Fail db " FAIL!", 0x0A, 0x0D, 0
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msg db "The system is now in x64 mode. Is this not beautiful ?", 0x0A, 0x0D, 0
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NoLongMode db 0x0A, 0x0D, "ERROR : Your computer is not designed for x64 OS", 0
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@ -278,6 +287,7 @@ NextTRAM dq 0x0B8000 ; Last position of cursor
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VIDEO_MODE64 dq 0
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VGA_HEIGHT64 dq 0
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VGA_X dq 0
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A20_OK db 0
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main64:
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pop qword [VGA_HEIGHT64]
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@ -304,18 +314,17 @@ main64:
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mov esi, EnA20
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call write
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cmp BYTE [A20_OK], 1
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je .A20Success
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mov bl, 0x0C
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mov esi, Fail
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call write
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jmp Die
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.A20Success:
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mov bl, 0x0A
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mov esi, Pass
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call write
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mov bl, 0x0F
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mov esi, KernSearch
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call write
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mov bl, 0x0A
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mov esi, Pass
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call write
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mov bl, 0x0F
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mov esi, txt
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call write
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@ -328,6 +337,7 @@ main64:
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mov esi, msg
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call write
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jmp Die
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; times 1024 nop
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