more of bootloader, tiny kernel stub
This commit is contained in:
parent
aeff38fe15
commit
cdc7b2ae53
7 changed files with 313 additions and 51 deletions
2
.gitignore
vendored
Normal file
2
.gitignore
vendored
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@ -0,0 +1,2 @@
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obj/
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out/
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@ -1,7 +1,9 @@
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0x0000 - 0x03ff : interrupt vector table
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0x0400 - 0x04ff : bios data area
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0x0500 - 0x05ff : structure pointers
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0x00 dword : fat pointer
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0x00 : fat
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0x04 : root directory
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0x08 : kernel
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0x0600 - 0x1fff : not assigned
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0x2000 - 0x3fff : memory map
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for each word : 1 page
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17
makefile
17
makefile
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@ -1,10 +1,23 @@
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floppy: out bootloader
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mkfs.fat -C -f 1 -F 12 -n "PORTLAND OS" -R 2 -S 512 out/floppy.img 1440
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floppy: out bootloader files
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mkfs.fat -C -f 1 -F 12 -n "PORTLAND OS" -R 4 -S 512 out/floppy.img 1440
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mkdir out/floppy_mount
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mount out/floppy.img out/floppy_mount
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cp out/fs/* out/floppy_mount/
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umount out/floppy_mount
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dd if=obj/bootloader.bin of=out/floppy.img bs=1 seek=62 conv=notrunc
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bootloader: obj
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nasm src/bootloader.bin -o obj/bootloader.bin
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kernel: obj out
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gcc -c src/kernel/main.c -o obj/kmain.o -ffreestanding
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gcc -c src/kernel/vga.c -o obj/kvga.o -ffreestanding
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ld obj/kmain.o obj/kvga.o -o out/kernel.out -nostdlib --oformat=i386-aout
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files: kernel
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mkdir out/fs
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cp out/kernel.out out/fs/kernel.sys
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obj:
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mkdir -p obj
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@ -17,20 +17,22 @@
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pointers:
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.fat equ 0x0500
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.root_dir equ 0x0504
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.kernel equ 0x0508
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fat_header:
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.oem_name equ 0x7c03;mkfs.fat - ignored
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.bytes_per_sector equ 0x7c0b;0x0200 - assumed
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.sectors_per_cluster equ 0x7c0d;0x01 - assumed
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.reserved_sectors equ 0x7c0e;0x0002 - other values handled
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.reserved_sectors equ 0x7c0e;0x0004 - other values handled
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.n_fats equ 0x7c10;0x01 - assumed
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.directory_entries equ 0x7c11; -
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.root_dir_entries equ 0x7c11; -
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.n_sectors equ 0x7c13;0x0b40 -
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.media_type equ 0x7c15; -
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.sectors_per_fat equ 0x7c16; - handled
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.sectors_per_track equ 0x7c18;0x0012 -
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.sides equ 0x7c1a;0x0002 -
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.hidden_sectors equ 0x7c1c;0x0000_0000 - assumed
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.hidden_sectors equ 0x7c1c;0x0000_0000 - assumed, top half used as scratch for sector number of cluster 0
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.long_sectors equ 0x7c20;0x0000_0000 - assumed
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.drive_number equ 0x7c24; - ignored, used as scratch
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.flags equ 0x7c25; - ignored
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@ -148,13 +150,165 @@ memory:
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jne halt
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mov ax, word [fat_header.sectors_per_fat]
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xor ecx, ecx
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mov cx, word [fat_header.reserved_sectors]
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call allocate_and_load
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mov dword [pointers.fat], ebx
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mov ax, word [fat_header.root_dir_entries]
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dec ax
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shr ax, 4
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inc ax
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xor ecx, ecx
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mov cx, word [fat_header.reserved_sectors]
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add cx, word [fat_header.sectors_per_fat]
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jnc .no_carry
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or ecx, 0x0001_0000
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.no_carry:
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call allocate_and_load
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mov dword [pointers.root_dir], ebx
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xor edx, edx
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mov dx, word [fat_header.root_dir_entries]
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shl edx, 5
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add edx, ebx
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find_kernel:
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mov eax, 0x6e_72_65_6b;kern
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mov ecx, 0x20_20_6c_65;el
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mov ebx, dword [pointers.root_dir]
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.loop:
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test dword [ebx], eax
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jne .next
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test dword [ebx + 4], ecx
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jne .next
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test word [ebx + 8], 0x79_73;sy
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jne .next
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test byte [ebx + 10], 0x73;s
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je .found
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.next:
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add ebx, 32
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test ebx, edx
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jne .loop
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jmp halt
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.found:
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mov byte [allocate_and_load.load], 0xc3;ret
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mov eax, dword [ebx + 0x1c]
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dec eax
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shr eax, 9
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inc eax
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test eax, 0xffff_0000
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jnz halt
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push word [ebx + 0x1a]
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call allocate_and_load
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mov dword [pointers.kernel], ebx
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mov ax, word [fat_header.root_dir_entries]
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dec ax
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shr ax, 4
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dec ax
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add ax, word [fat_header.reserved_sectors]
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jc halt
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add ax, word [fat_header.sectors_per_fat]
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jc halt
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mov word [fat_header.hidden_sectors + 2], ax
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load_kernel:
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mov word [dap.length], 0x0001
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mov word [dap.offset], bx
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xor bx, bx
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shr ebx, 4
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test ebx, 0xffff_0000
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jnz halt
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mov word [dap.segment], bx
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xor edx, edx
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pop dx
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mov word [dap.start + 2], 0x0000
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mov ah, 0x42
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mov si, dap
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.loop:
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mov cx, dx
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add cx, word [fat_header.hidden_sectors + 2]
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jc halt
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mov word [dap.start], cx
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int 0x13
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mov ebx, dword [pointers.fat]
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add ebx, edx
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add ebx, edx
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add ebx, edx
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xor edx, edx
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mov dx, word [ebx + 1]
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shl edx, 8
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mov dl, byte [ebx]
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add word [dap.segment], 0x0020
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jc halt
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mov ecx, edx
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and ecx, 0x0ff8
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test ecx, 0x0ff8
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jne .loop
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mov ebx, dword [pointers.kernel]
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;Parse kernel executable header,
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;Go through relocation tables,
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;Get kernel_start.
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cli
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lgdt [gdt]
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mov eax, cr0
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or al, 0x01
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mov cr0, eax
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jmp 0x08:kernel_start;get start from file header
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gdt:
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dw 0x28
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dd gdt + 6
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dq 0x0000_0000_0000_0000
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dq 0x0040_9a00_0000_7fff;0x000000 - 0x007fff
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dq 0x0040_9200_0000_7fff
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dq 0x00c0_9a00_8000_0ff7;0x008000 - 0xffffff
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dq 0x00c0_9200_8000_0ff7
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dap:
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dw 0x0010
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.length dw 0x0003
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.offset dw 0x7e00
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.segment dw 0x0000
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.start dd 0x0000_0001
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.start_h dd 0x0000_0000
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;ecx = sector
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;ax = sector count
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;bx out = address of start
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allocate_and_load:
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mov word [dap.length], ax
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mov dword [dap.start], ecx
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dec ax
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shr ax, 3
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inc ax
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fat_allocate:
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mov bx, 0x200e
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xor cx, cx
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mov dx, 0x2200
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@ -189,50 +343,17 @@ fat_allocate:
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and ebx, 0x0000_dfff
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shl ebx, 12
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mov dword [pointers.fat], ebx
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mov dl, byte [fat_header.drive_number]
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mov ax, word [fat_header.reserved_sectors]
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mov word [dap.start], ax
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mov word [dap.offset], bx
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shr ebx, 16
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and bx, 0xf000
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mov word [dap.segment], bx
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.load:
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mov eax, ebx
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mov word [dap.offset], ax
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shr eax, 4
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and ax, 0xf000
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mov word [dap.segment], ax
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mov ah, 0x42
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mov si, dap
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int 0x15
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int 0x13
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mov ebx, dword [pointers.fat]
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;fat loaded - load kernel
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cli
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lgdt [gdt]
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mov eax, cr0
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or al, 0x01
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mov cr0, eax
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jmp 0x08:pmode
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gdt:
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dw 0x28
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dd gdt + 6
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dq 0x0000_0000_0000_0000
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dq 0x0040_9a00_0000_7fff;0x000000 - 0x007fff
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dq 0x0040_9200_0000_7fff
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dq 0x00c0_9a00_8000_0ff7;0x008000 - 0xffffff
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dq 0x00c0_9200_8000_0ff7
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dap:
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dw 0x0010
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.length dw 0x0001
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.offset dw 0x7e00
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.segment dw 0x0000
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.start dq 1
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allocate:
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;TODO
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ret
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halt:
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@ -240,7 +361,3 @@ halt:
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.hlt:
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hlt
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jmp .hlt
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bits 32
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pmode:
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26
src/kernel/main.c
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26
src/kernel/main.c
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@ -0,0 +1,26 @@
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/*
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Copyright 2019 Benji Dial
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Permission to use, copy, modify, and/or distribute this
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software for any purpose with or without fee is hereby
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granted, provided that the above copyright notice and this
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permission notice appear in all copies.
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THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS
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ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO
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EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
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INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
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RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
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ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
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OF THIS SOFTWARE.
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*/
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#include "vga.h"
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void main(void) {
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put_sz("Welcome to Portland version 0.0.8!\n");
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while (1)
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put_sz("|\b/\b-\b\\\b");
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}
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71
src/kernel/vga.c
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71
src/kernel/vga.c
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/*
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Copyright 2019 Benji Dial
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Permission to use, copy, modify, and/or distribute this
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software for any purpose with or without fee is hereby
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granted, provided that the above copyright notice and this
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permission notice appear in all copies.
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THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS
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ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO
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EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
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INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
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RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
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ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
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OF THIS SOFTWARE.
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*/
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#include "vga.h"
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uint16_t cursor_pos = 0;
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uint8_t color = 0xf0;
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#define cols 80
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#define rows 25
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void scroll(void) {
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cursor_pos -= cols * 2;
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uint32_t *limit = (uint32_t *)(VGA_BUFFER + cols * (rows - 1));
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for (uint32_t *i = (uint32_t *)VGA_BUFFER; i < limit; ++i)
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*i = *(i + cols / 2);
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limit += cols / 2;
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uint32_t fill = (color * 0x0100 + (uint8_t)' ') * 0x00010001;
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for (uint32_t *i = limit - cols / 2; i < limit; ++i)
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*i = fill;
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}
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void put_char(uint8_t ch) {
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switch (ch) {
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case '\b':
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if (cursor_pos)
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VGA_BUFFER[cursor_pos -= 2] = (uint8_t)' ';
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break;
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case '\t':
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while ((cursor_pos % (cols * 2)) % 20)
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put_char(' ');
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break;
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case '\n':
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if ((cursor_pos = (cursor_pos / (cols * 2) + 1) * (cols * 2)) >= cols * rows * 2)
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scroll();
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break;
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default:
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VGA_BUFFER[cursor_pos++] = ch;
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VGA_BUFFER[cursor_pos++] = color;
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if (cursor_pos == (cols * rows * 2))
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scroll();
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}
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}
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void put_sz(uint8_t *sz) {
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while (*sz)
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put_char(*(sz++));
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}
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void move_cursor(uint8_t col, uint8_t row) {
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cursor_pos = (col + row * cols) * 2;
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}
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void set_color(uint8_t c) {
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color = c;
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}
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31
src/kernel/vga.h
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31
src/kernel/vga.h
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@ -0,0 +1,31 @@
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/*
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Copyright 2019 Benji Dial
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Permission to use, copy, modify, and/or distribute this
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software for any purpose with or without fee is hereby
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granted, provided that the above copyright notice and this
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||||
permission notice appear in all copies.
|
||||
|
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THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS
|
||||
ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
|
||||
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO
|
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EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
|
||||
INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
|
||||
RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
|
||||
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
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||||
ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
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OF THIS SOFTWARE.
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*/
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#include <stdint.h>
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#ifndef VGA_H
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#define VGA_H
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#define VGA_BUFFER ((uint8_t *)0x000b8000)
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void put_char(uint8_t ch);
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void put_sz(uint8_t *s);
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void move_cursor(uint8_t col, uint8_t row);
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void set_color(uint8_t c);
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#endif
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Reference in a new issue