CTAOS v1
This commit is contained in:
449
loader.asm
Normal file
449
loader.asm
Normal file
@ -0,0 +1,449 @@
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[BITS 32]
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global start
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start: mov esp, _sys_stack ; This points the stack to our new stack area
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jmp stublet
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; This part MUST be 4byte aligned, so we solve that issue using 'ALIGN 4'
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ALIGN 4
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mboot:
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; Multiboot macros to make a few lines later more readable
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MULTIBOOT_PAGE_ALIGN equ 1<<0
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MULTIBOOT_MEMORY_INFO equ 1<<1
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MULTIBOOT_AOUT_KLUDGE equ 1<<16
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MULTIBOOT_HEADER_MAGIC equ 0x1BADB002
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MULTIBOOT_HEADER_FLAGS equ MULTIBOOT_PAGE_ALIGN | MULTIBOOT_MEMORY_INFO | MULTIBOOT_AOUT_KLUDGE
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MULTIBOOT_CHECKSUM equ -(MULTIBOOT_HEADER_MAGIC + MULTIBOOT_HEADER_FLAGS)
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EXTERN code, bss, end
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; This is the GRUB Multiboot header. A boot signature
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dd MULTIBOOT_HEADER_MAGIC
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dd MULTIBOOT_HEADER_FLAGS
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dd MULTIBOOT_CHECKSUM
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; AOUT kludge - must be physical addresses. Make a note of these:
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; The linker script fills in the data for these ones!
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dd mboot
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dd code
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dd bss
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dd end
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dd start
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; This is an endless loop here. Make a note of this: Later on, we
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; will insert an 'extern _main', followed by 'call _main', right
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; before the 'jmp $'.
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stublet:
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extern _main
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call _main
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jmp $
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; !!! GDT !!!
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; This will set up our new segment registers. We need to do
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; something special in order to set CS. We do what is called a
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; far jump. A jump that includes a segment as well as an offset.
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; This is declared in C as 'extern void gdt_flush();'
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global _gdt_flush ; Allows the C code to link to this
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extern _gp ; Says that '_gp' is in another file
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_gdt_flush:
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lgdt [_gp] ; Load the GDT with our '_gp' which is a special pointer
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mov ax, 0x10 ; 0x10 is the offset in the GDT to our 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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jmp 0x08:flush2 ; 0x08 is the offset to our code segment: Far jump!
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flush2:
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ret ; Returns back to the C code!
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; !!! IDT !!!
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; Loads the IDT defined in '_idtp'
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global _idt_load
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extern _idtp
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_idt_load:
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lidt [_idtp]
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ret
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; !!! ISRs !!!
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global _isr0
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global _isr1
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global _isr2
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global _isr3
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global _isr4
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global _isr5
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global _isr6
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global _isr7
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global _isr8
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global _isr9
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global _isr10
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global _isr11
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global _isr12
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global _isr13
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global _isr14
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global _isr15
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global _isr16
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global _isr17
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global _isr18
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global _isr19
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global _isr20
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global _isr21
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global _isr22
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global _isr23
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global _isr24
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global _isr25
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global _isr26
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global _isr27
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global _isr28
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global _isr29
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global _isr30
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global _isr31
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_isr0:
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cli
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push byte 0; A normal ISR stub that pops a dummy error code to keep a
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; uniform stack frame
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push byte 0
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jmp isr_common_stub
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_isr1:
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cli
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push byte 0
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push byte 1
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jmp isr_common_stub
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_isr2:
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cli
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push byte 0
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push byte 2
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jmp isr_common_stub
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_isr3:
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cli
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push byte 0
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push byte 3
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jmp isr_common_stub
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_isr4:
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cli
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push byte 0
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push byte 4
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jmp isr_common_stub
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_isr5:
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cli
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push byte 0
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push byte 5
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jmp isr_common_stub
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_isr6:
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cli
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push byte 0
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push byte 6
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jmp isr_common_stub
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_isr7:
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cli
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push byte 0
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push byte 7
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jmp isr_common_stub
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_isr8:
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cli
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push byte 8
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jmp isr_common_stub
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_isr9:
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cli
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push byte 0
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push byte 9
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jmp isr_common_stub
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_isr10:
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cli
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push byte 10
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jmp isr_common_stub
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_isr11:
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cli
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push byte 11
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jmp isr_common_stub
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_isr12:
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cli
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push byte 12
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jmp isr_common_stub
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_isr13:
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cli
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push byte 13
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jmp isr_common_stub
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_isr14:
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cli
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push byte 14
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jmp isr_common_stub
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_isr15:
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cli
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push byte 0
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push byte 15
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jmp isr_common_stub
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_isr16:
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cli
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push byte 0
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push byte 16
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jmp isr_common_stub
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_isr17:
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cli
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push byte 0
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push byte 17
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jmp isr_common_stub
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_isr18:
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cli
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push byte 0
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push byte 18
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jmp isr_common_stub
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_isr19:
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cli
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push byte 0
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push byte 19
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jmp isr_common_stub
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_isr20:
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cli
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push byte 0
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push byte 20
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jmp isr_common_stub
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_isr21:
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cli
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push byte 0
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push byte 21
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jmp isr_common_stub
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_isr22:
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cli
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push byte 0
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push byte 22
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jmp isr_common_stub
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_isr23:
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cli
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push byte 0
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push byte 23
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jmp isr_common_stub
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_isr24:
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cli
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push byte 0
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push byte 24
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jmp isr_common_stub
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_isr25:
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cli
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push byte 0
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push byte 25
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jmp isr_common_stub
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_isr26:
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cli
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push byte 0
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push byte 26
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jmp isr_common_stub
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_isr27:
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cli
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push byte 0
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push byte 27
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jmp isr_common_stub
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_isr28:
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cli
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push byte 0
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push byte 28
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jmp isr_common_stub
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_isr29:
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cli
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push byte 0
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push byte 29
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jmp isr_common_stub
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_isr30:
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cli
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push byte 0
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push byte 30
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jmp isr_common_stub
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_isr31:
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cli
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push byte 0
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push byte 31
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jmp isr_common_stub
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extern _fault_handler
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isr_common_stub:
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pusha
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push ds
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push es
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push fs
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push gs
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mov ax, 0x10 ; Load the Kernel Data Segment descriptor!
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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 eax, esp ; Push us the stack
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push eax
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mov eax, _fault_handler
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call eax ; A special call, preserves the 'eip' register
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pop eax
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pop gs
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pop fs
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pop es
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pop ds
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popa
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add esp, 8 ; Cleans up the pushed error code and pushed ISR number
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iret ; pops 5 things at once: CS, EIP, EFLAGS, SS, and ESP!
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; !!! IRQ !!!
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global _irq0
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global _irq1
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global _irq2
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global _irq3
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global _irq4
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global _irq5
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global _irq6
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global _irq7
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global _irq8
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global _irq9
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global _irq10
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global _irq11
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global _irq12
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global _irq13
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global _irq14
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global _irq15
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; 32: IRQ0
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_irq0:
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cli
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push byte 0
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push byte 32; Note that these don't push an error code on the stack:
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; We need to push a dummy error code
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jmp irq_common_stub
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; 33: IRQ1
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_irq1:
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cli
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push byte 0
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push byte 33
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jmp irq_common_stub
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; 34: IRQ2
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_irq2:
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cli
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push byte 0
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push byte 34
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jmp irq_common_stub
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; 35: IRQ3
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_irq3:
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cli
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push byte 0
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push byte 35
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jmp irq_common_stub
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; 36: IRQ4
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_irq4:
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cli
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push byte 0
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push byte 36
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jmp irq_common_stub
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; 37: IRQ5
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_irq5:
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cli
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push byte 0
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push byte 37
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jmp irq_common_stub
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; 38: IRQ6
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_irq6:
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cli
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push byte 0
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push byte 38
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jmp irq_common_stub
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; 39: IRQ7
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_irq7:
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cli
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push byte 0
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push byte 39
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jmp irq_common_stub
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; 40: IRQ8
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_irq8:
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cli
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push byte 0
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push byte 40
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jmp irq_common_stub
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; 41: IRQ9
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_irq9:
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cli
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push byte 0
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push byte 41
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jmp irq_common_stub
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; 42: IRQ10
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_irq10:
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cli
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push byte 0
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push byte 42
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jmp irq_common_stub
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; 43: IRQ11
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_irq11:
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cli
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push byte 0
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push byte 43
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jmp irq_common_stub
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; 44: IRQ12
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_irq12:
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cli
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push byte 0
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push byte 44
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jmp irq_common_stub
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; 45: IRQ13
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_irq13:
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cli
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push byte 0
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push byte 45
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jmp irq_common_stub
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; 46: IRQ14
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_irq14:
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cli
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push byte 0
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push byte 46
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jmp irq_common_stub
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; 47: IRQ15
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_irq15:
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cli
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push byte 0
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push byte 47
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jmp irq_common_stub
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extern _irq_handler
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; This is a stub that we have created for IRQ based ISRs. This calls
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; '_irq_handler' in our C code. We need to create this in an 'irq.c'
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irq_common_stub:
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pusha
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push ds
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push es
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push fs
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push gs
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mov ax, 0x10
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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 eax, esp
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push eax
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mov eax, _irq_handler
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call eax
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pop eax
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pop gs
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pop fs
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pop es
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pop ds
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popa
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add esp, 8
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iret
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SECTION .bss
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resb 8192 ; This reserves 8KBytes of memory here
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_sys_stack:
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