Jeremy Soller
152 lines
2.7 KiB
NASM
152 lines
2.7 KiB
NASM
SECTION .text
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USE16
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args:
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.kernel_base dq 0x100000
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.kernel_size dq 0
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.stack_base dq 0
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.stack_size dq 0
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.env_base dq 0
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.env_size dq 0
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startup:
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; enable A20-Line via IO-Port 92, might not work on all motherboards
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in al, 0x92
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or al, 2
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out 0x92, al
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%ifdef KERNEL
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mov edi, [args.kernel_base]
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mov ecx, (kernel_file.end - kernel_file)
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mov [args.kernel_size], ecx
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mov eax, (kernel_file - boot)/512
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add ecx, 511
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shr ecx, 9
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call load_extent
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%else
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%ifdef FILESYSTEM
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mov eax, (filesystem - boot) / 512
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%else
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call find_redoxfs_partition
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%endif
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call redoxfs
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test eax, eax
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jnz error
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%endif
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jmp .loaded_kernel
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.loaded_kernel:
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call memory_map
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call vesa
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mov si, init_fpu_msg
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call print
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call initialize.fpu
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mov si, init_sse_msg
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call print
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call initialize.sse
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mov si, startup_arch_msg
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call print
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jmp startup_arch
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; load a disk extent into high memory
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; eax - sector address
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; ecx - sector count
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; edi - destination
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load_extent:
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; loading kernel to 1MiB
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; move part of kernel to startup_end via bootsector#load and then copy it up
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; repeat until all of the kernel is loaded
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buffer_size_sectors equ 127
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.lp:
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cmp ecx, buffer_size_sectors
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jb .break
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; saving counter
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push eax
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push ecx
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push edi
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; populating buffer
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mov ecx, buffer_size_sectors
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mov bx, startup_end
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mov dx, 0x0
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; load sectors
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call load
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; set up unreal mode
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call unreal
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pop edi
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; move data
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mov esi, startup_end
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mov ecx, buffer_size_sectors * 512 / 4
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cld
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a32 rep movsd
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pop ecx
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pop eax
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add eax, buffer_size_sectors
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sub ecx, buffer_size_sectors
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jmp .lp
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.break:
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; load the part of the kernel that does not fill the buffer completely
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test ecx, ecx
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jz .finish ; if cx = 0 => skip
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push ecx
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push edi
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mov bx, startup_end
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mov dx, 0x0
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call load
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; moving remnants of kernel
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call unreal
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pop edi
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pop ecx
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mov esi, startup_end
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shl ecx, 7 ; * 512 / 4
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cld
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a32 rep movsd
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.finish:
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call print_line
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ret
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%include "config.asm"
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%include "descriptor_flags.inc"
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%include "gdt_entry.inc"
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%include "unreal.asm"
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%include "memory_map.asm"
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%include "vesa.asm"
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%include "initialize.asm"
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%ifndef KERNEL
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%include "redoxfs.asm"
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%ifndef FILESYSTEM
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%include "partitions.asm"
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%endif
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%endif
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init_fpu_msg: db "Init FPU",13,10,0
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init_sse_msg: db "Init SSE",13,10,0
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init_pit_msg: db "Init PIT",13,10,0
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init_pic_msg: db "Init PIC",13,10,0
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startup_arch_msg: db "Startup Arch",13,10,0
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