Clean up - and correct detection handling of multiple active partitions
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+30
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@@ -3,7 +3,7 @@ BITS 16
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; SLRboot
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; Bootloader for SingOS
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; version 0.2.0.3-exp
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; version 0.2.1.0-exp
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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cli
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jmp long 0x0000:start
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@@ -36,34 +36,36 @@ call print ; Call our string-printing routine
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xor bx, bx
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xor cx, cx
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mov ax, [partition_1.active_partition]
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cmp ax, 0x80
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cmp al, 0x80
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jne check_p_2
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mov bx, 0x01 ; Partion 1 active
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inc cx
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check_p_2:
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mov ax, [partition_2.active_partition]
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cmp ax, 0x80
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cmp al, 0x80
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jne check_p_3
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inc cx
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mov bx, 0x02 ; Partion 2 active
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check_p_3:
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mov ax, [partition_3.active_partition]
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cmp ax, 0x80
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cmp al, 0x80
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jne check_p_4
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inc cx
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mov bx, 0x03 ; Partion 3 active
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check_p_4:
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mov ax, [partition_4.active_partition]
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mov al, [partition_4.active_partition]
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cmp ax, 0x80
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jne eval_active_partion_number
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inc cx
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mov bx, 0x04 ; Partion 4 active
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cli
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hlt
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eval_active_partion_number:
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cmp cx, 1
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je boot_partition
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; here goes wait call, for the user to enter debug mode.
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; Wating for 2 seconds:
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@@ -76,18 +78,14 @@ xor ax, ax
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mov ah, 0x01 ; BIOS call to wait for key
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int 0x16
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boot_partition:
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; IMPORTANT bx, has to hold the value 1-4 for the partiotion that wanted to be booted.
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mov bx, 2
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mov ax, partition_1
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.loop:
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cmp bx, 1
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je break
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add ax, 0x10
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;call dumpax
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dec bx
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jmp .loop
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break:
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@@ -102,7 +100,6 @@ add bx, 2 ; next part
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mov ax, [bx]
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mov WORD [DAPACK.lba_addr_dw_low + 1], ax
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call dumpax
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mov WORD [DAPACK.blkcnt], 0x01
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mov WORD [DAPACK.db_addr_segment], 0x0000
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mov WORD [DAPACK.db_addr_offset], 0x7c00
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@@ -112,109 +109,28 @@ mov ah, 0x42 ; READ
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mov dl, [disk_identifier]
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int 0x13
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jc endcarrycheck ; An error ocurred when reading from disk.
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; If no error then jump to volume boot record
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notcarry:
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jmp long 0x0:0x7c00
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cli
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hlt
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%IF 0
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cli
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jmp long 0x0000:start
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start:
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xor ax, ax
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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 [disk_identifier], dl
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; initialize stack
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; Set up 4K stack after this bootloader
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; [Remember: Effective Address = Segment*16 + Offset]
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mov ax, 0x7C0 ; Set 'ax' equal to the location of this bootloader divided by 16
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add ax, 0x20 ; Skip over the size of the bootloader divided by 16
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mov ss, ax ; Set 'ss' to this location (the beginning of our stack region)
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mov sp, 8192 ; Set 'ss:sp' to the top of our 8K stack
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sti
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mov si, message ; Put address of the null-terminated string to output into 'si'
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call print ; Call our string-printing routine
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mov si, enter_debug_mode
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call print
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call printCRLF
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;%IF 0
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; here goes wait call, for the user to enter debug mode.
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; Wating for 2 seconds:
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mov ah, 0x86 ; code for waiting interupt call
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mov cx, 0x001e ; high count of microseconds
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mov dx, 0x8480 ; low count
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int 0x15
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.busy_wait_for_key:
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xor ax, ax
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mov ah, 0x01 ; BIOS call to wait for key
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int 0x16
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jnz debug_mode
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; entering system check:
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mov si, enter_system_check
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mov si, sys_check_ok ; Put address of the null-terminated string to output into 'si'
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call print ; Call our string-printing routine
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mov si, boot_system ; Put address of the null-terminated string to output into 'si'
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call print ; Call our string-printing routine
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;This goes first as to now overwrite %ah and %al.
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;mov ax, 0x0050
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;mov es, ax ;Section to write into
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;mov ah, 0x2 ;Read sectors from drive
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;mov al, 0x08 ;Number of sectors to read (31 * 512 = 15872 bytes)
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;mov ch, 0x0 ;Low 8 bits of cylinder
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;mov cl, 0x11 ;First sector to read (bits 0-5), upper bits of cylinder (bits 6-7)
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;mov dh, 0x0 ;Head number
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;mov dl, [disk_identifier] ;Drive number
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;mov bx, 0x0000 ;Offset into section
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;int 0x13 ;Low level disk services
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;jnc notcarry
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;mov si, error_str
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;call print
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;jmp endcarrycheck
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notcarry:
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;mov si, success_str
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;call print
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;call printCRLF
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mov ax, 0x0
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mov ds, ax
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mov ax, 89 ; lba adress
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jmp 0x50:0x0000 ; Jump to the kernel
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; If we did not suceed to read from disk
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endcarrycheck:
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mov si, error_str
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call print
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cli ; Clear the Interrupt Flag (disable external interrupts)
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hlt ; Halt the CPU (until the next external interrupt)
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debug_mode:
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mov si, .welcome_debug
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mov si, welcome_debug
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call print
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cli ; Clear the Interrupt Flag (disable external interrupts)
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hlt
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.welcome_debug db 'This is debug mode', 0
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printCRLF:
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mov ah, 0xE
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mov al, 13
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int 0x10
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mov al, 10
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int 0x10
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ret
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%ENDIF
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;Routine for printing a 'ax' as hex
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dumpax:
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pusha ; save registers
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@@ -237,6 +153,14 @@ loop .loop
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popa ; restore registers
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ret
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printCRLF:
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mov ah, 0xE
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mov al, 13
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int 0x10
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mov al, 10
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int 0x10
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ret
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; Routine for outputting string in 'si' register to screen
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print:
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mov ah, 0xE ; Specify 'int 0x10' 'teletype output' function
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@@ -251,13 +175,10 @@ jmp .printchar ; Repeat for the next character
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ret
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data:
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message db 'SLRboot for SingOS! v0.2.0.3-exp',13,10,0
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;enter_debug_mode db 'Press d to enter bootloader debug mode',13,10,0
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;enter_system_check db 'Performing system check:',13,10,0
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;sys_check_ok db 'System check ok', 13, 10, 0
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;boot_system db 'Read SingOS from disk', 13, 10, 0
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;error_str db 'Error', 0
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;success_str db 'Success', 0
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message db 'SLRboot for SingOS! v0.2.1.0-exp',13,10,0
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enter_debug_mode db 'Press d to enter bootloader debug mode',13,10,0
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welcome_debug db 'Debug mode v.0.0.1:',13,10,0
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error_str db 'Error', 0
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boot_this_partition: dw 0
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disk_identifier db 0
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@@ -283,7 +204,7 @@ partition_1:
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.size db 0x00, 0xC8, 0x03, 0x00
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partition_2:
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.active_partition db 0x80
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.active_partition db 0x00
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.start_CHS db 0x8C, 0x3E, 0x0F
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.disk_type db 0x83
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.end_CHS db 0xFF, 0xFF, 0xFF
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@@ -310,24 +231,4 @@ times 510-($-$$) db 0
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dw 0xAA55 ; => 0x55 0xAA (little endian byte order)
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; bootloder debug_mode goes here
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times 8192-($-$$) db 0
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; mov si, 0x7be
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; cmp byte [si], al
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; jne 0x33
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; add si, 0x10
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; cmp si, 0x7fe
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; jne 0x24
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; jmp 0x49
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; mov ah, 2
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; mov al, 1
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; mov bx, 0x7c00
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; mov dl, 0x80
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; mov dh, byte [si + 1]
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; mov cx, word [si + 2]
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; int 0x13
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; jmp long 0:0x7c00
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; jmp 0x49
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times 8192-($-$$) db 0
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