mirror of
https://github.com/kkk2z/CatOS.git
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73 lines
1,014 B
ArmAsm
73 lines
1,014 B
ArmAsm
BITS 16
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ORG 0x7C00
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START:
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; Set up the stack
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mov ax, 0x07C0
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mov ss, ax
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mov sp, 0xFFFF
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; Set up the data segment
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mov ax, 0x07C0
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mov ds, ax
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mov es, ax
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; Set up the GDT
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cli
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lgdt [gdt_descriptor]
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mov eax, cr0
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or eax, 1
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mov cr0, eax
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jmp 08h:code_segment
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BITS 32
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code_segment:
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; Set up the segment registers
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mov ax, data_segment
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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 ss, ax
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; Set up the stack pointer
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mov esp, 0x9FC00
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; Call kernel main function
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call kernel_main
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hang:
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; Hang the system
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jmp hang
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; Define the GDT
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gdt_start:
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; Null descriptor
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dd 0
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dd 0
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; Code segment descriptor
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dw 0xFFFF
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dw 0x0000
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db 0x00
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db 0x9A
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db 0xCF
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db 0x00
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; Data segment descriptor
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dw 0xFFFF
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dw 0x0000
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db 0x00
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db 0x92
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db 0xCF
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db 0x00
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gdt_end:
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gdt_descriptor:
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dw gdt_end - gdt_start - 1
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dd gdt_start
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TIMES 510 - ($ - $$) db 0
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DW 0xAA55
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