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218 lines
5.9 KiB
218 lines
5.9 KiB
ORG 0x7C00
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BITS 16
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; Bootloader for SingOS
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; version 0.1.0.10-exp
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;
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; Please edit the version number if any changes is made, the last number
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; represent the build number.
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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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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%ENDIF
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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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;call printCRLF
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;mov ax, cs
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;call dumpax
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;mov ax, start
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;call dumpax
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;call printCRLF
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mov dl, [disk_identifier]
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xor ax, ax
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mov al, dl
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call dumpax
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call printCRLF
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mov ax, 0x50
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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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endcarrycheck:
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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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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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;Routine for printing a 'ax' as hex
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dumpax:
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pusha ; save registers
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mov bx, ax
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mov ah, 0xE ; Teletype output
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mov cx, 4 ; 4 nipples in a 16 bit word
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.loop:
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rol bx, 4 ; rotate to next nipple
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mov al, bl ; we copy to al because we need to mask only the low 4 bits
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and al, 1111b ; Do the masking
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add al, '0' ; convert to ASCII
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cmp al, '9' ; If we are greater than 9 ascii, we add 7 to make digit 10 be represented as 'A'
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jbe .skip ; -|-
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add al, 7 ; -|-
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.skip: ; -|-
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int 0x10 ; BIOS call 'output'
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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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; [AL = Character, BH = Page Number, BL = Colour (in graphics mode)]
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.printchar:
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lodsb ; Load byte at address SI into AL, and increment SI
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cmp al, 0
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je .done ; If the character is zero (NUL), stop writing the string
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int 0x10 ; Otherwise, print the character via 'int 0x10'
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jmp .printchar ; Repeat for the next character
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.done:
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ret
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data:
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message db 'Bootloader for SingOS! v0.1.0.10-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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disk_identifier db 0
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; Pad to 510 bytes (boot sector size minus 2) with 0s, and finish with the two-byte standard boot signature
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times 446-($-$$) db 0 ; First partion entry
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db 0x80 ; active partition
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db 0, 0x00, 0x17 ; First sector CHS
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db 0x18 ; Disk type (Other) (Why 18, answer ':' ^ ')' )
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db 0xff, 0xff, 0xff ; Ending CHS values
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db 0x18, 0, 0, 0x00 ; Staring LBA
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db 0, 0xff, 0xff, 0xff ; Size
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db 0x00
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db 0x0, 0x0, 0x0
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db 0x0
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db 0x0, 0x0, 0x0
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db 0x00, 0x00, 0x00, 0x00
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db 0x0, 0x00, 0x00, 0x00
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times 478-($-$$) db 0 ; Third partion entry
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times 494-($-$$) db 0 ; Forth partion entry
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times 510-($-$$) 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-($-$$) db 0
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; From Version 0.0.3 we are concatinate the bootloader and the kernel after compile time
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;%include "kernel.nasm"
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;times 8192-($-$$) db 0
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;80
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;00 01 00
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;00
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;3F 60 21
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;00 00 00 00
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;00 10 09 00
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;00
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;FE FF FF
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;EF
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;FE FF FF
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;B0 0E 00 00
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;40 03 00 00
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;00
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;00 00 00
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;00
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;00 00 00
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;00 00 00 00
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;00 00 00 00
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;00
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;00
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;00 00 00 00
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;00 00 00 00
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;00 00 00
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