After C Switch

build.sh

@@ -1,32 +1,27 @@
 #!/bin/bash
 
-# Create ./build dir if it doesn't exist
+[[ -d ./build ]] || mkdir build
-if !(test -d ./build); then
+
-    mkdir ./build
+rm -rf ./build/**
-    echo "Created ./build/ directory!"
-fi
 
 # Bootloader
-nasm -fbin src/boot.asm -o ./build/boot.bin
+nasm -fbin ./src/boot.asm -o ./build/boot.bin
-nasm -fbin src/filetable.asm -o ./build/filetable.bin
 
 # Kernel
-nasm -fbin src/kernel.asm -o ./build/kernel.bin
+nasm -felf32 ./src/kernel/entry.asm -o ./build/entry.o
 
-# Programs
+for file in ./src/kernel/**.c; do
-nasm -fbin src/fs/calc.asm -o ./build/calc.bin
+    filename=$(basename "$file" .c)
-nasm -fbin src/fs/edit.asm -o ./build/edit.bin
+    i386-elf-gcc -ffreestanding -Wall -Wextra -m32 -c $file -o ./build/$filename.o
+done
 
-cat ./build/calc.bin ./build/edit.bin > ./build/files.bin
+i386-elf-ld -o ./build/kernel.bin -Ttext 0x1000 --oformat binary ./build/**.o
 
-# Final binary
+# OS Image
-cat ./build/boot.bin ./build/filetable.bin ./build/kernel.bin ./build/files.bin > ./build/temp.bin
+cat build/boot.bin build/kernel.bin > build/os.bin
-dd if=/dev/zero of=./build/kern.iso bs=512 count=2880
+dd if=/dev/zero of=./kern.iso bs=512 count=2880
-dd if=./build/temp.bin of=./build/kern.iso conv=notrunc
+dd if=./build/os.bin of=./kern.iso conv=notrunc
-rm -rf ./build/**.bin
-
-echo "Built kern.iso!"
 
 # Run QEMU
-echo "Running QEMU..."
+qemu-system-x86_64 -drive format=raw,file="./kern.iso",index=0,media=disk -m 256M -accel tcg
-qemu-system-x86_64 -drive format=raw,file="./build/kern.iso",index=0,media=disk -m 256M
+

src/boot.asm

@@ -1,98 +1,149 @@
-[org 0x7c00]
 [bits 16]
+[org 0x7c00]
 [global start]
 
+%define KERNEL_LOC 0x1000
+%define KERNEL_SIZE 20      ; 20 Sectors -> 10kB
+%define ENDL 0x0a, 0x0d
+%define VIDMEM 0xb800
+
 start:
-    ; Setup
+    mov [driveNum], dl   ; Store the drive number
+
+    ; Set up the stack
     xor ax, ax
     mov es, ax
     mov ds, ax
     mov bp, 0x7c00
     mov sp, bp
 
-    ; Save drive number
+    ; Setup screen
-    mov byte [driveNumber], dl
+    mov ax, 3       ; 80x25 Text mode
+    int 0x10
+    mov ah, 1       ; Hide cursor
+    mov cx, 0x2607
+    int 0x10
 
-    ; Print boot message
+    mov byte [0xb800], 'A'
-    mov si, bootMsg
+.read:
-    call print
+    ; Location
-    mov dl, byte [driveNumber]
+    mov bx, KERNEL_LOC
-    call printHex
-    mov si, newline
-    call print
 
-    ; Read filetable from disk
+    ; CHS Location
-    mov bx, FILETAB_LOC ; Filetable location in memory
+    mov al, KERNEL_SIZE
-    mov es, bx
+    mov ch, 0   ; Cylinder
-    xor bx, bx
+    mov dh, 0   ; Head
+    mov cl, 2   ; Sector
+    mov dl, [driveNum]
 
-    mov ah, 2           ; Read from disk
+    mov ah, 2   ; Read from disk
-    mov al, 1           ; Read 1 sector (512B)
+    int 0x13    ; Read interrupt
 
-    mov dl, byte [driveNumber] ; Drive number
+    jc .diskErr
-    mov ch, 0           ; Cylinder
-    mov dh, 0           ; Head
-    mov cl, 2           ; Sector
-    int 0x13            ; INT 0x13 - Disk operations
 
-    jc readFail         ; CF will be set if the read fails
+    cli
+    lgdt [GDT_Descriptor]
+    ; Enable protected mode
+    mov eax, cr0
+    or eax, 1
+    mov cr0, eax
 
-    ; Read filetable from disk
+    ; Far jump to 32 bit mode!!
-    mov bx, KERNEL_LOC ; Filetable location in memory
+    jmp CODE_SEG:protected_start
-    mov es, bx
-    xor bx, bx
 
-    mov ah, 2           ; Read from disk
+.diskErr:
-    mov al, 4           ; Read 4 sectors (2kB)
+    dec byte [counter]
+    jnz .read
 
-    mov dl, byte [driveNumber] ; Drive number
+    mov si, diskErrMsg
-    mov ch, 0           ; Cylinder
+    mov bl, 0x04
-    mov dh, 0           ; Head
+    call puts
-    mov cl, 3           ; Sector
-    int 0x13            ; INT 0x13 - Disk operations
 
-    jc readFail         ; CF will be set if the read fails
+    cli
+    hlt
 
-    ; Setup segmentation
+;
-    mov ax, KERNEL_LOC
+; Prints a string
-    mov ds, ax
+; si: char* - String to print
+; bl: byte  - Color attribute
+;
+puts:
+    push ax
+    push es
+
+    mov ax, VIDMEM
+    mov es, ax
+    mov word di, [cursor]
+
+    mov ah, bl
+.loop:
+    lodsb               ; mov al, [si]; inc si
+    cmp al, 0
+    je .done
+    mov [es:di], ax     ; Really smart thing
+    add di, 2
+    jmp .loop
+.done:
+    mov [cursor], di
+    pop es
+    pop ax
+    ret
+
+;; Data
+driveNum: db 3
+counter: db 0
+cursor: dw 0
+
+; Strings
+msg: db "Booting...", 0
+diskErrMsg: db "Failed while reading from disk!", 0
+
+;; 32 Bit entry code
+[bits 32]
+protected_start:
+    ; Set up data and stack segments
+    mov ax, DATA_SEG 
+    mov ds, ax 
+    mov ss, ax 
     mov es, ax
     mov fs, ax
     mov gs, ax
 
-    ; Setup stack
+    ; Set up the stack pointer in protected mode
-    mov bp, 0xffff
+    mov ebp, 0x90000
-    mov sp, bp
+    mov esp, ebp
-    mov ax, 0x9000
-    mov ss, ax
 
-    mov bl, byte [driveNumber]
+    ; Perform the far jump
+    jmp KERNEL_LOC
+    
+;; GDT
+GDT_Start:
+    null_descriptor:    ; No clue why this exists
+        dd 0
+        dd 0
+    code_descriptor:    ; Memory for code
+        dw 0xffff       ; First 16 bits of limit
+        dw 0            ; 16 bits +
+        db 0            ; + 8 bits = 24 bits
+        db 0b10011010   ; p, dpl, s, type flags
+        db 0b11001111   ; Other flags, last 4 bits of limit
+        db 0            ; Base
+    data_descriptor:    ; Memory for data
+        dw 0xffff       ; First 16 bits of limit
+        dw 0            ; 16 bits +
+        db 0            ; + 8 bits = 24 bits
+        db 0b10010010   ; p, dpl, s, type flags
+        db 0b11001111   ; Other flags, last 4 bits of limit
+        db 0            ; Base
+GDT_End:
 
-    ; Setup video mode
+GDT_Descriptor:
-    mov ax, 0x0003
+    dw GDT_End - GDT_Start - 1  ; Size
-    int 0x10
+    dd GDT_Start        ; GDT Pointer
-    mov ah, 0x0b
-    mov bx, 0x0001
-    int 0x10
 
-    ; Far jump to the kernel (never returns)
+CODE_SEG equ code_descriptor - GDT_Start
-    jmp KERNEL_LOC:0x0000
+DATA_SEG equ data_descriptor - GDT_Start
-
-readFail:
-    mov si, diskErrorMsg
-    call print
-    cli
-    hlt
-
-%include "./src/lib/print.asm"
-
-driveNumber: db 0
-
-bootMsg: db ENDL, "Booting kern.", ENDL, "Booting from drive ", 0
-diskErrorMsg: db "Disk Error!", ENDL, 0
-
-FILETAB_LOC equ 0x1000
-KERNEL_LOC equ 0x2000
 
 times 510-($-$$) db 0
 dw 0xaa55
+

src/filetable.asm

@@ -1,22 +0,0 @@
-; ------------------
-;  Simple Filetable
-; ------------------
-;
-; 16 Byte entries
-; 0-9   - Filename
-; 10-12 - File extension (type)
-; 13    - Number of filetable entries
-; 14    - Starting Sector
-; 15    - Filesize in sectors (n * 512)
-;
-; ------------------
-
-filetable:
-    ; db 'all',0,0,0,0,0,0,0,'txt',0,1,7 ; all           - start: 1, size: 7
-    db 'boot',0,0,0,0,0,0, 'bin',0,1,1   ; boot.bin      - start: 1, size: 1
-    db 'filetable',0,      'txt',0,2,1   ; filetable.txt - start: 2, size: 1
-    db 'kernel',0,0,0,0,   'bin',0,3,4   ; kernel.bin    - start: 3, size: 4
-    db 'calc',0,0,0,0,0,0, 'bin',0,7,1   ; calc.bin      - start: 7, size: 1
-    db 'edit',0,0,0,0,0,0, 'bin',0,8,4   ; edit.bin      - start: 8, size: 2
-
-times 512-($-$$) db 0

src/fs/calc.asm

@@ -1,32 +0,0 @@
-[bits 16]
-
-start:
-    pusha
-    
-    mov si, msg
-    call print
-
-    xor ax, ax
-    int 0x16
-
-    mov dl, ah
-    call printHexByte
-
-    xor ax, ax
-    int 0x16
-
-    popa
-.return:
-    mov ax, 0x2000
-    mov ds, ax
-    mov es, ax
-    mov fs, ax
-    mov gs, ax
-
-    jmp 0x2000:0x0000
-
-%include "./src/lib/print.asm"
-
-msg: db "Hello!", ENDL, 0
-
-times 512-($-$$) db 0

src/fs/edit.asm

@@ -1,312 +0,0 @@
-[bits 16]
-
-start:
-    pusha
-    mov byte [driveNum], dl
-
-hexEditor:
-    call clearText
-
-    mov di, 0x0e60      ; Offset in vidmem (2nd to last line)
-    mov si, hexModeMsg
-    call drawString
-    mov di, 0x0f00      ; Last line
-    mov si, controlsMsg
-    call drawString
-
-    mov di, hexCode
-    xor cx, cx      ; Clear counter
-
-    mov dx, [codeLen]
-    call printHexByte
-    mov si, bytesMsg
-    call print
-    mov si, newline
-    call print
-
-    cmp word [codeLen], 0
-    je getHexCh
-
-    mov cx, [codeLen]
-.printCode:  
-    mov dl, [di]
-    call printHexByte
-    mov ah, 0x0e
-    mov al, ' '
-    int 0x10
-    inc di
-    dec cx
-    jnz .printCode
-
-    mov cx, [codeLen]
-getHexCh:
-    xor ax, ax
-    int 0x16
-    cmp al, RUN_CODE
-    je .runInput
-    cmp al, QUIT_EDIT
-    je return
-    cmp al, SAVE_FILE
-    je save
-    cmp al, OPEN_FILE
-    je open
-    cmp al, 0x08    ; Backspace
-    je .backspace
-
-    xor ah, ah
-    call asciiToHex ; Get the hex digit into bx
-
-    cmp ax, 15      ; Check if it's a hex character
-    jg getHexCh     ; If not, ignore it
-
-    inc cx
-    cmp cx, 2       ; Check if we've gotten a whole byte (2 hex digits/nibbles)
-    je .putByte
-    mov [hexByte], al
-    jmp getHexCh
-.putByte:
-    cmp di, hexCode+510
-    jge getHexCh    ; Max length reached
-    rol byte [hexByte], 4
-    or byte [hexByte], al
-    mov al, [hexByte]
-    stosb
-    mov dx, [hexByte]
-    call printHexByte
-    inc word [codeLen]
-    xor cx, cx
-    mov al, ' '
-    mov ah, 0x0e
-    int 0x10
-    jmp getHexCh
-.backspace:
-    cmp word [codeLen], 0 ; Check if there's anything to delete
-    je getHexCh         ; If not, ignore
-    mov byte [hexByte], 0
-    dec word [codeLen]
-    xor cx, cx
-    mov byte [di], 0
-    dec di
-    mov si, hexBackspace
-    call print
-    jmp getHexCh
-.runInput:
-    mov si, runMsg
-    call print
-
-    pusha
-    push es
-    call hexCode       ;! Runs arbitrary code (may break everything)
-    pop es
-    popa
-
-    mov si, ranMsg
-    call print
-    xor ax, ax
-    int 0x16
-    jmp hexEditor
-return:
-    popa
-
-    mov ax, 0x2000
-    mov es, ax
-    xor bx, bx
-
-    mov ds, ax
-    mov fs, ax
-    mov gs, ax
-    jmp 0x2000:0x0000
-
-; Saves a file
-save:
-    mov dl, 9
-    mov si, saveFileMsg
-    call getInput
-    mov byte al, [filename]
-    cmp byte al, 0
-    je getHexCh
-
-    ; Call saveFile
-    mov byte dl, [driveNum]
-    push word filename
-    push word binFile   ; Filetype, TODO: More filetypes other than .bin
-    push word 1         ; TODO: Dynamic filesize
-    push word 0x8000    ; Program location (this segment)
-    push word savedData ; Offset (hex code location)
-    call saveFile       ; Returns exit code in al
-    add sp, 10          ; Stack bs
-
-    mov ax, 0x8000
-    mov es, ax
-    mov fs, ax
-
-    cmp al, 0           ; Won't be 1 (File not found) so must be disk error
-    jne .error
-
-    jmp getHexCh
-.error:
-    mov si, diskErrMsg
-    mov di, 0x0f00      ; Last line
-    call drawString
-    
-    jmp getHexCh
-
-; Opens a file
-open:
-    mov dl, 11
-    mov si, openFileMsg
-    call getInput
-    mov byte al, [filename]
-    cmp byte al, 0
-    je getHexCh
-
-    ; Call loadFile
-    mov byte dl, [driveNum]
-    push word filename
-    push word 0x8000
-    push word hexCode
-    call loadFile
-
-    mov ax, 0x8000
-    mov es, ax
-    mov fs, ax
-
-    cmp al, 1
-    je .notFound
-    cmp al, 2
-    je .diskErr
-
-    ; Success
-    jmp hexEditor
-.notFound:
-    mov si, notFoundMsg
-    jmp .err
-.diskErr:
-    mov si, diskErrMsg
-.err:
-    mov di, 0x0f00
-    call drawString
-    xor ax, ax
-    int 0x16
-    jmp hexEditor
-
-;
-; Gets a filename (10 chars, If less, padded with Nulls)
-; Outputs the filename in the filename buffer
-; si - Prompt string (Null terminated)
-; dl - String offset
-;
-getInput:
-    pusha
-    push es
-
-    mov di, 0x0f00      ; Last line
-    call drawString     ; si should contain the string
-
-    mov ah, 2       ; Move cursor to input position
-    mov dh, 24      ; Last line
-    int 0x10
-
-    mov di, filename
-    xor cx, cx      ; Entered filename length
-.loop:
-    xor ax, ax
-    int 0x16
-
-    cmp al, 0xD     ; User pressed enter
-    je .done
-    cmp al, 8       ; Backspace
-    je .backspace
-    cmp al, 27      ; Escape
-    je .escape
-    cmp cx, 10      ; Filename too long
-    je .loop
-
-    mov ah, 0x0e
-    int 0x10
-    mov [di], al
-    inc di
-    inc cx
-    jmp .loop
-.backspace:
-    cmp cx, 0
-    je .loop
-    dec cx
-    dec di
-    mov si, textBackspace
-    call print
-    jmp .loop
-.escape:
-    xor cx, cx
-    mov si, filename
-.done:
-    cmp cx, 10
-    je .after
-    mov byte [di], 0
-    inc cx
-    inc di
-.after:
-    mov ah, 2       ; Move cursor
-    xor dx, dx      ; 0,0
-    int 0x10
-
-    pop es
-    popa
-    ret
-
-; Expects al to contain an ASCII character, will set bx to it's hex equivalent
-asciiToHex:
-    cmp al, 'F'
-    jle .upperCase
-    sub al, 32
-.upperCase:
-    cmp al, '9'
-    jle .getHex
-    sub al, 7
-.getHex:
-    sub al, '0'
-    ret
-
-;; Includes
-%include "./src/lib/print.asm"
-%include "./src/lib/disk.asm"
-
-;; Variables
-hexModeMsg: db " -- HEX -- ", 0
-textModeMsg: db " -- Text -- ", 0
-controlsMsg: db "'$' Execute; ^Q Quit; ^S Save; ^O Open", 0
-saveFileMsg: db "Save as:                              ", 0 ; Make sure to erase the controls
-openFileMsg: db "Open file:                            ", 0
-bytesMsg: db " Bytes", 0
-; savedMsg: db "Saved file as '", 0
-; openedMsg: db "Editing file '", 0
-runMsg: db ENDL, ENDL, 0
-ranMsg: db ENDL, ENDL, " - Finished Execution - ", ENDL, 0
-notFoundMsg: db "File not found!           ", 0 ; Erase the user input
-diskErrMsg: db  "Disk Error!               ", 0
-
-; Filetypes
-binFile: db "bin"
-txtFile: db "txt"
-
-hexBackspace: db 8,8,8,'  ',8,8,0
-textBackspace: db 8,' ',8,0
-
-driveNum: db 0
-hexByte: db 0
-
-filenameLen: db 0
-filename: times 10 db 0
-
-;; Constants
-RUN_CODE equ '$'
-QUIT_EDIT equ 'q'
-NEW_FILE equ 'n'
-SAVE_FILE equ 's'
-OPEN_FILE equ 'o'
-
-times 3*512-($-$$) db 0
-
-savedData:
-    hexCode: times 510 db 0     ; Code buffer
-    codeLen: dw 0               ; Hopefully we don't overflow :)

src/kernel.asm

@@ -1,503 +0,0 @@
-[bits 16]
-
-start:
-    ; Save the drive number from stack
-    mov byte [driveNum], dl
-
-    mov bx, 0x2000
-    mov es, bx
-    xor bx, bx
-
-    call resetTextMode
-    call clearText
-
-    ; Print start message
-    mov si, startMsg
-    call print
-
-; Runs prompt
-input:
-    mov si, prompt
-    call print
-    mov ax, 0x2000
-    mov ds, ax
-    mov es, ax
-    mov si, userInput
-    xor cx, cx
-.loop:
-    xor ax, ax      ; Clear ax
-    int 0x16        ; Get a character
-
-    cmp al, 0x0d    ; Compare with CR
-    je .enter
-    cmp al, 0x08    ; Compare with BS
-    je .backspace
-
-    mov ah, 0x0e    ; Echo back input
-    mov bh, 0
-    int 0x10
-
-    mov [si], al    ; Add the input to userInput
-    inc cx
-    inc si
-    jmp .loop
-.backspace:
-    cmp cx, 0       ; Check if we can backspace
-    je .loop
-    mov byte [si], 0
-    dec si
-    dec cx
-    mov al, 0x08
-    int 0x10
-    mov al, ' '
-    int 0x10
-    mov al, 0x08
-    int 0x10
-    jmp .loop
-.enter:
-    push si
-    mov si, newline
-    call print
-    pop si
-    mov byte [si], 0 ; NULL terminate userInput (Replaces CR)
-    mov byte [inputLen], cl
-
-    cmp byte [inputLen], 0 ; Check if user input something
-    je input
-
-tokenize:           ; Tokenize 
-    mov si, userInput
-.loop:
-    inc si
-    cmp byte [si], 0
-    je .done
-    cmp byte [si], ' '
-    jne .loop
-    mov byte [si], 0
-    jmp .loop
-.done:
-
-; Runs a command in userInput
-; Expects tokenized input
-runCommand:
-    mov di, lsCmd
-    call .cmp
-    je fileList
-
-    mov di, gfxCmd
-    call .cmp
-    je graphicsTest
-
-    mov di, helpCmd
-    call .cmp
-    je help
-
-    mov di, rebootCmd
-    call .cmp
-    je reboot
-
-    mov di, clearCmd
-    call .cmp
-    je clear
-
-    mov di, exitCmd
-    call .cmp
-    je shutdown
-
-    mov di, rmCmd
-    call .cmp
-    je rmFile
-
-    jmp .end
-.cmp:
-    push cx
-    mov si, userInput
-    repe cmpsb
-    pop cx
-    ret
-.end:
-
-;
-; Load Program - Takes userInput and tries to run that file
-;
-loadProgram:
-    mov di, userInput
-    mov bx, FILETAB_LOC
-    mov es, bx
-    xor bx, bx      ; Get [es:bx] to be start of filetable
-.nextCh:
-    mov al, [es:bx]
-    cmp al, 0       ; Check for end of filetable
-    je .notFound
-
-    cmp al, [di]    ; Check for starting character
-    je .beginSearch
-
-    add bx, 16      ; Move to the next entry
-    jmp .nextCh
-.beginSearch:
-    push bx         ; Save position, if it doesn't equal
-    mov byte cl, [inputLen]
-.searchLoop:
-    mov al, [es:bx]
-    inc bx
-    cmp al, [di]
-    jne .restartSearch
-
-    dec cl
-    jz .match
-    inc di
-    jmp .searchLoop
-.match:
-    mov al, [es:bx]
-    cmp al, 0       ; Check if we are at the end of a filename
-    je foundProgram
-.restartSearch:
-    mov di, userInput
-    pop bx
-    inc bx
-    jmp .nextCh
-.notFound:
-    mov si, fileNotFoundMsg
-    call print
-    jmp input
-    
-foundProgram:
-    mov al, [es:bx]
-    cmp al, 0       ; Loop until we find the extension
-    jne .getMetadata    
-    inc bx
-    jmp foundProgram
-.getMetadata:
-    mov al, [es:bx]
-    mov [fileExt], al
-    inc bx
-    mov al, [es:bx]
-    mov [fileExt+1], al
-    inc bx
-    mov al, [es:bx]
-    mov [fileExt+2], al
-    inc bx
-
-    inc bx          ; Ignore Number of FT entries for now
-
-    ; mov cl, [es:bx] ; Starting sector
-    ; inc bx
-    ; mov al, [es:bx] ; Number of sectors to read
-    ; push ax         ; Save file size
-
-    ; mov ah, 0       ; Reset disk system
-    ; mov dl, byte [driveNum]
-    ; int 0x13
-
-    ; mov bx, PROGRAM_LOC
-    ; mov es, bx
-    ; xor bx, bx      ; [es:bx] - Place to load out program
-
-    ; mov ah, 2       ; Read sectors into memory
-    ; mov dl, byte [driveNum]
-    ; mov ch, 0       ; Cylinder
-    ; mov dh, 0       ; Head
-    ; int 0x13
-
-    mov byte dl, [driveNum] ; Drive number
-    push word userInput     ; Filename
-    push word PROGRAM_LOC   ; Dest. segment
-    push word 0x0000        ; Dest. offset
-    call loadFile
-
-    cmp byte al, 0
-    je .loaded     ; Loaded file successfully
-
-    mov si, programLoadFailMsg
-    call print
-
-    jmp input
-.loaded:
-    ; Check file extension. If 'bin', then run, if 'txt', print
-    pop ax      ; Restore file size
-
-    mov cx, 3   ; Check file extension
-    mov si, fileExt 
-    mov ax, 0x2000
-    mov es, ax
-    mov di, binExt
-    repe cmpsb
-    jne .printText  ; TODO: Check for more file extensions
-
-    mov dl, [driveNum]
-
-    mov ax, PROGRAM_LOC
-    mov ds, ax
-    mov es, ax
-    mov fs, ax
-    mov gs, ax
-
-    jmp PROGRAM_LOC:0x0000
-.printText:
-    mov bx, PROGRAM_LOC
-    mov es, bx
-    xor bx, bx
-    mov cx, 512
-    mul cx
-    mov cx, ax
-    mov ah, 0x0e
-.textLoop:
-    mov al, [es:bx]
-    cmp al, 0
-    je .rep
-    int 0x10
-.rep:
-    inc bx
-    dec cx
-    jnz .textLoop
-
-    mov si, newline
-    call print
-    jmp input
-
-;
-; Help - Prints the help message (helpMsg)
-;
-help:
-    mov si, helpMsg
-    call print
-    jmp input
-
-;
-; Clears the screen
-;
-clear:
-    call clearText
-    jmp input
-
-;
-; Shuts the system down
-; Only works for QEMU
-;
-shutdown:
-    mov ax, 0x2000
-    mov dx, 0x0604
-    out dx, ax
-
-;
-; Remove file (rm)
-;
-rmFile:
-    call removeFile
-    jmp input
-
-;
-; File list (ls)
-;
-fileList:
-    mov bx, FILETAB_LOC
-    mov es, bx
-    xor bx, bx
-
-    mov al, 2       ; Read from disk
-    mov byte dl, [driveNum]
-    mov ch, 0       ; Cylinder
-    mov dh, 0       ; Head
-    mov cl, 2       ; Sector
-    mov al, 1       ; Read 1 sector
-    int 0x13        ; Move filetable to es:bx
-
-    mov si, fileListMsg
-    call print
-
-; Prints the filetable
-printFiletable:
-    mov bx, FILETAB_LOC
-    mov es, bx
-    xor bx, bx
-    xor cx, cx      ; Entry byte couter
-    mov ah, 0x0e    ; Prepare for printing
-.filenameLoop:
-    mov al, [es:bx] ; Get filename character
-    cmp al, 0       ; Check if it's NULL
-    je .filenameEnd ; If so, end the filename reading
-    cmp cx, 9       ; Check if we already read 10 Bytes
-    je .filenameEnd 
-    int 0x10        ; Else print the character
-    inc cx          ; Increment byte counter
-    inc bx
-    jmp .filenameLoop
-.filenameEnd:
-    push cx
-.skipNull:
-    cmp cx, 0
-    je .done
-    cmp cx, 10      ; Check if we're at the end of filename
-    je .fileExt     ; If so, print extension
-    inc cx
-    inc bx
-    jmp .skipNull
-.fileExt:
-    ; push cx         ; Save the counter
-    mov al, '.'     ; Print a "." to separate filename from extension
-    int 0x10
-.fileExtLoop:
-    mov al, [es:bx]
-    cmp cx, 13      ; Check if we printed 3 characters
-    je .fileExtEnd
-    cmp al, 0
-    je .fileExtEnd
-    int 0x10
-    inc cx
-    inc bx
-    jmp .fileExtLoop
-.fileExtEnd:
-    cmp cx, 13
-    je .whitespace
-    inc cx
-    inc bx
-    mov al, ' '     ; Print whitespace
-    int 0x10
-    jmp .fileExtEnd
-.whitespace:
-    pop cx
-.wsLoop:
-    cmp cx, 11      ; Max filename length + 1 for spacing
-    je .fileInfo
-    mov al, ' '
-    int 0x10
-    inc cx
-    jmp .wsLoop
-.fileInfo:
-    ; Entry number
-    mov dl, [es:bx]
-    call printHexByte
-    inc bx
-    mov al, ' '
-    int 0x10
-    ; Start sector
-    mov dl, [es:bx]
-    call printHexByte
-    inc bx
-    mov al, ' '
-    int 0x10
-    int 0x10
-    int 0x10
-    ; File size
-    mov al, [es:bx]
-    inc bx
-    cmp al, 1
-    je .oneSector       ; Only print 512B
-    shr al, 1           ; Divide by 2
-    jc .oneHalf         ; We had an odd number of sectors
-    add al, '0'
-    int 0x10
-    mov si, kilobyteText
-    call print
-    jmp .repeat
-.oneHalf:
-    add al, '0'
-    int 0x10
-    mov si, oneHalfText
-    call print
-    jmp .repeat
-.oneSector:
-    mov si, sectorLenText
-    call print
-.repeat:
-    mov si, newline
-    call print
-    xor cx, cx
-    jmp .filenameLoop
-.done:
-    jmp input
-
-;
-; Graphics Mode Test
-;
-graphicsTest:
-    call resetGraphicsMode
-
-    ; Test square
-    mov ah, 0x0c        ; Write gfx pixel
-    mov al, 0x02        ; Green
-    mov bh, 0           ; Page number
-
-    mov cx, 100         ; Column number
-    mov dx, 100         ; Row number
-    int 0x10
-.colLoop:
-    inc cx
-    int 0x10
-    cmp cx, 150
-    jne .colLoop
-
-    inc dx
-    int 0x10
-    mov cx, 99
-    cmp dx, 150
-    jne .colLoop
-.done:
-    mov si, startMsg
-    call print
-
-    xor ax, ax
-    int 0x16
-
-    call resetTextMode
-    jmp input
-
-;
-; Reboots the OS
-;
-reboot: jmp 0xffff:0x0000
-
-;; Includes
-%include "./src/lib/print.asm"
-%include "./src/lib/screen.asm"
-%include "./src/lib/disk.asm"
-
-;; Variables
-driveNum: db 0
-
-startMsg: db "kern.", ENDL, ENDL, 0 ; The bootup message
-prompt: db "> ", 0 ; Prompt for input
-fileNotFoundMsg: db "File not found!", ENDL, 0 ; User tries to load nonexistent file
-programLoadFailMsg: db "Couldn't load file!", ENDL, 0 ; File load fail
-sectorLenText: db "512B", 0
-kilobyteText: db "kB", 0
-oneHalfText: db ".5kB", 0
-
-fileListMsg: db " Filename      E# St   Size ", ENDL, \
-                "----------    ------- ------", ENDL, 0
-
-helpMsg: db "Available Commands:", ENDL, \
-            " clear  | Clears the screen", ENDL, \
-            " edit   | Opens the code editor", ENDL, \
-            " exit   | Shuts the system down", ENDL, \
-            " gfx    | Graphics mode test", ENDL, \
-            " help   | Prints this message", ENDL, \
-            " ls     | List all files", ENDL, \
-            " reboot | Reboots the system", ENDL, \
-            " rm     | Removes a file", ENDL, ENDL, 0
-
-; Commands
-; TODO: Put these into a file or something
-clearCmd: db "clear", 0
-exitCmd: db "exit"
-gfxCmd: db "gfx", 0
-helpCmd: db "help", 0
-lsCmd: db "ls", 0
-rebootCmd: db "reboot", 0
-rmCmd: db "rm", 0
-
-; Files
-fileExt: db "   ", 0
-binExt: db "bin", 0
-txtExt: db "txt", 0
-
-inputLen: db 0
-tokenCount: db 0
-userInput: times 80 db 0
-
-;; Constants
-FILETAB_LOC equ 0x1000
-PROGRAM_LOC equ 0x8000
-
-times 4*512-($-$$) db 0

src/kernel/entry.asm

@@ -0,0 +1,9 @@
+[bits 32]
+[global _start]
+
+[extern main]
+
+_start:
+    call main
+    cli
+    hlt

src/kernel/main.c

@@ -0,0 +1,6 @@
+#include "screen.h"
+
+void main() {
+    print("Hello, World!", 0x0f);
+}
+

src/kernel/screen.c

@@ -0,0 +1,21 @@
+#include "screen.h"
+
+unsigned int cursor = 0;
+
+void putc(char c, char attr) {
+    int mem = VIDMEM + cursor * 2;
+    *(char*)(mem) = c;
+    *(char*)(mem+1) = attr;
+
+    cursor++;
+}
+
+void print(char* s, char attr) {
+    int i = 0;
+    char c = *s;
+    while (c != '\0') {
+        putc(c, attr);
+        c = *(s + ++i);
+    }
+}
+

src/kernel/screen.h

@@ -0,0 +1,9 @@
+#ifndef SCREEN_H
+#define SCREEN_H
+
+#define VIDMEM 0xb8000
+
+void putc(char c, char attr);
+void print(char* s, char attr);
+
+#endif

src/lib/disk.asm

@@ -1,334 +0,0 @@
-;
-; Loads a file from the filetable into a memory location
-; Params:
-;   dl - Disk number (byte)
-;   Filename (Null terminated)
-;   Destination location segment
-;   Destination location offset
-;
-; Returns:
-;   al - Exit code : 0 - Success; 1 - File not found; 2 - Disk error
-;
-loadFile:
-    ; Func prologue
-    push bp
-    mov bp, sp
-    push bx
-    push fs
-    push cx
-    push dx
-    push si
-    push es
-
-    mov byte [diskNum], dl
-    mov bx, [bp+4]      ; src Offset
-    mov fs, [bp+6]      ; src Segment
-    mov si, [bp+8]      ; Filename
-
-    push bx
-
-    mov cx, 10
-    mov di, fileName
-.getFilename:
-    lodsb           ; mov byte al, [si]; inc si
-    cmp al, 0       ; End of fileName
-    je .filenamePad
-    stosb
-    loop .getFilename
-    jmp .filenameDone
-.filenamePad: 
-    dec si          ; Fill the rest with Null
-.filenamePadLoop:
-    stosb
-    loop .filenamePadLoop
-.filenameDone:
-    mov si, fileName
-    call print
-
-    mov ax, FILETAB_LOC
-    mov es, ax
-    xor di, di      ; es:di - Filetable location
-    mov si, fileName
-.fileNameCheck:
-    mov al, [es:di]
-    cmp al, 0       ; End of filetable
-    je .notFound
-
-    cmp al, [si]
-    je .beginCmp
-
-    add di, 16
-    jmp .fileNameCheck
-.beginCmp:
-    push di
-    mov cl, 10
-.cmpLoop:
-    mov al, [es:di]
-    inc di
-    cmp al, [si]
-    jne .redoCheck
-
-    dec cl 
-    jz .found
-    inc si
-    jmp .cmpLoop
-.redoCheck:
-    mov si, fileName
-    pop di
-    add di, 16
-    jmp .fileNameCheck
-.notFound:
-    mov byte [exitCode], NOT_FOUND
-    jmp .done
-.found:
-    add di, 3       ; Skip extension
-    inc di          ; Skip Number of entries
-
-    xor ax, ax      ; Reset disk
-    mov dl, [diskNum]
-    int 0x13
-
-    mov ch, 0       ; Cylinder
-    mov dh, 0       ; Head
-    mov cl, [es:di] ; Sector
-    inc di
-    mov al, [es:di] ; Length in sectors
-    mov bx, fs
-    mov es, bx
-    pop bx
-    mov dx, bx
-    call printHexByte
-    mov ah, 2       ; Read from disk
-    int 0x13
-
-    jnc .done
-
-    mov byte [exitCode], DISK_ERROR
-.done:
-    ; Func epilogue
-    pop es
-    pop si
-    pop dx
-    pop cx
-    pop fs
-    pop bx
-    mov sp, bp
-    pop bp
-    mov byte al, [exitCode]
-    ret
-
-;
-; Saves a file to the disk and updates filetable
-; dl - Disk number
-; Params:
-;   Filename (Null terminated)
-;   Filetype (Null terminated)
-;   Filesize (Byte)
-;   Source location segment
-;   Source location offset
-;
-; Returns:
-;   al - Exit code : 0 - Success; 1 - File not found; 2 - Disk error
-;
-saveFile:
-    ; Func prologue
-    push bp
-    mov bp, sp
-    push bx
-    push fs
-    push cx
-    push dx
-    push si
-    push es
-
-    mov byte [diskNum], dl
-    mov bx, [bp+4]      ; src Offset
-    mov fs, [bp+6]      ; src Segment
-    mov cx, [bp+8]      ; Filesize 
-    mov ax, [bp+10]     ; Filetype
-
-    push bx
-
-    mov byte [filesize], cl
-
-    mov si, ax
-    mov di, filetype
-    mov cx, 3
-    rep movsb
-
-    mov si, [bp+12] ; Filename
-    mov cx, 10
-    mov di, fileName
-.getFilename:
-    lodsb           ; mov byte al, [si]; inc si
-    cmp al, 0       ; End of fileName
-    je .filenamePad
-    stosb
-    loop .getFilename
-    jmp .filenameDone
-.filenamePad: 
-    dec si          ; Fill the rest with Null
-.filenamePadLoop:
-    stosb
-    loop .filenamePadLoop
-.filenameDone:
-    mov ax, FILETAB_LOC
-    mov es, ax
-    xor di, di      ; es:di - Filetable location
-    mov si, fileName
-.fileNameCheck:
-    mov byte al, [es:di+14] ; Starting sector
-    cmp al, 0       ; No file, create one
-    je createFile
-
-    add byte al, [es:di+15] ; Filesize 
-    mov byte [availableSector], al
-
-    mov al, [es:di]
-    cmp al, 0       ; End of filetable
-    je createFile   ; File doesn't exist, create new one
-
-    cmp al, [si]
-    je .beginCmp
-
-    add di, 16
-    jmp .fileNameCheck
-.beginCmp:
-    push di
-    mov cl, 10
-.cmpLoop:
-    mov al, [es:di]
-    inc di
-    cmp al, [si]
-    jne .redoCheck
-
-    dec cl 
-    jz .found
-    inc si
-    jmp .cmpLoop
-.redoCheck:
-    mov si, fileName
-    pop di
-    add di, 16
-    jmp .fileNameCheck
-.found:             ; File already exists (override)
-    ; TODO: Ask user if they want to override file
-    add di, 3       ; Skip extension
-    inc di          ; Skip Number of entries
-
-    xor ax, ax      ; Reset disk
-    mov dl, [diskNum]
-    int 0x13
-
-    ; TODO: Override current file
-    ; push fs
-    ; mov ch, 0       ; Cylinder
-    ; mov dh, 0       ; Head
-    ; mov cl, [es:di] ; Sector
-    ; inc di
-    ; mov al, [es:di] ; Length in sectors
-    ; mov ah, 3       ; Write to disk
-    ; pop es          ; es:bx - Destination
-    ; int 0x13
-
-    ; jnc returnToCaller
-
-    mov byte [exitCode], DISK_ERROR
-    jmp returnToCaller  ; TODO: Fix this
-
-createFile:             ; Appends a file to the filetable.
-    mov di, FILETAB_LOC
-    mov es, di
-    xor di, di
-
-.filetabEnd:            ; Move to the end of filetable
-    cmp byte [es:di], 0
-    je .filetabEndDone
-    add di, 16
-    jmp .filetabEnd
-.filetabEndDone:
-    mov cx, 10
-    mov si, fileName
-    rep movsb           ; Append the fileName
-    mov cx, 3
-    mov si, filetype
-    rep movsb           ; Append the extension
-    mov byte [es:di], 0 ; Number of entries
-    inc di
-    mov byte al, [availableSector]
-    stosb               ; Starting sector
-    mov byte al, [filesize]
-    stosb               ; File length in sectors
-
-    ; Write changed filetable to disk
-    ;! If filetable size changes, this will have to change (probably)
-    mov bx, FILETAB_LOC
-    mov es, bx
-    xor bx, bx          ; es:bx - Filetable location
-    mov dl, [diskNum]
-    mov ah, 3           ; Write to disk
-    mov al, 1           ; Write 1 sector
-    mov ch, 0           ; Cylinder
-    mov dh, 0           ; Head
-    mov cl, 2           ; Sector
-    int 0x13
-
-    jnc writeFileData
-
-    mov byte [exitCode], DISK_ERROR
-    jmp returnToCaller
-
-writeFileData:          ; Writes file data to the disk
-    mov ax, 0x8000          ; Source segment
-    mov es, ax
-    pop bx              ; es:bx - Source
-    mov ah, 3           ; Write to disk
-    mov byte al, [filesize]
-    mov dl, [diskNum]
-    mov ch, 0           ; Cylinder
-    mov dh, 0           ; Head
-    mov byte cl, [availableSector]
-    int 0x13
-
-    jnc returnToCaller
-
-    mov byte [exitCode], DISK_ERROR  ; Exit code - Disk Error
-
-returnToCaller:
-    ; Func epilogue
-    pop es
-    pop si
-    pop dx
-    pop cx
-    pop fs
-    pop bx
-    mov sp, bp
-    pop bp
-    mov byte al, [exitCode]
-    ret
-
-;
-; Removes a file from the disk/filetable
-;
-; Params:
-;   Filename
-;
-removeFile:
-    ret
-    
-;; Variables
-availableSector: db 0
-exitCode: db 0
-
-diskNum: db 0
-filesize: db 0
-filetype: times 3 db 0
-fileName: times 10 db 0
-
-;; Constants
-FILETAB_LOC equ 0x1000
-
-; Exit codes
-SUCCESS equ 0
-NOT_FOUND equ 1
-DISK_ERROR equ 2

src/lib/print.asm

@@ -1,129 +0,0 @@
-;
-; Prints a string
-; si - Pointer to NULL terminated string
-;
-print:
-    pusha
-    mov ah, 0x0e
-    mov bl, 0x1f
-    mov bh, 0
-.loop:
-    lodsb           ; Load [si] into al; Increment si
-    or al, al
-    jz .done
-    int 0x10
-    jmp .loop
-.done:
-    popa
-    ret
-
-;
-; Prints a hex value
-; dx - Value to print in Hex
-;
-printHex:
-    pusha
-    xor cx, cx      ; Init counter
-.loop:
-    cmp cx, 4       ; Check for loop end
-    je .done
-    mov ax, dx      ; Copy dx to ax
-    and ax, 0x000f  ; Get last nibble (4 bits) of ax
-    add ax, '0'     ; Convert number to an ASCII number (0-9)
-    cmp ax, '9'     ; Check if number was less than 9, meaning we can use it
-    jle .addChar
-    add ax, 0x07    ; Convert to letter (A-F)
-.addChar:
-    mov bx, hexString + 5
-    sub bx, cx      ; Get position of current hex character
-    mov [bx], al
-    ror dx, 4       ; Rotate bits of dx (0x1a2b -> 0xb1a2)
-    inc cx          ; Increment the counter
-    jmp .loop
-.done: 
-    mov si, hexString
-    call print
-    popa
-    ret
-
-;
-; Prints a hex byte
-; dl - Hex byte
-;
-printHexByte:
-    pusha
-    xor cx, cx
-    mov bh, 0
-    mov bl, 0x1f    ; White on blue
-.loop:
-    mov al, dl
-    and al, 0xF0
-    ror al, 4
-    add al, '0'
-    cmp al, '9'
-    jle .hexNum
-    add al, 7
-.hexNum:
-    mov ah, 0x0e
-    int 0x10
-    inc cx
-    cmp cx, 2
-    je .done
-    ror dl, 4
-    jmp .loop
-.done:
-    popa
-    ret
-
-hexString: db "0x0000", 0
-
-;
-; Clears the screen in text mode
-; Assumes VGA text 3 - 80x25, 16 color
-;
-clearText:
-    pusha
-    push es
-    mov ax, 0x0b800
-    mov es, ax
-    xor di, di      ; es:di - b800:0000
-
-    mov al, ' '     ; Fill with spaces
-    mov ah, 0x17    ; White on blue
-    mov cx, 80*25 
-    rep stosw 
-
-    mov ah, 2
-    xor dx, dx      ; Set cursor to 0,0
-    int 0x10
-
-    pop es
-    popa
-    ret
-
-;
-; Writes a string into video memory
-; di - Video memory offset
-; si - string
-;
-drawString:
-    pusha
-    push es         ; For some reason doesn't get stored in pusha
-    mov ax, VIDMEM
-    mov es, ax
-.loop:
-    cmp byte [si], 0
-    je .after
-    movsb
-    mov byte [es:di], 0x1f  ; White on blue
-    inc di
-    jmp .loop
-.after:
-    pop es
-    popa
-    ret
-
-; Usefull definitions
-%define ENDL 0x0a, 0x0d
-VIDMEM equ 0x0b800
-newline: db ENDL, 0 ; CRLF

src/lib/screen.asm

@@ -1,24 +0,0 @@
-resetTextMode: 
-    pusha
-
-    mov ah, 0       ; Set mode
-    mov al, 0x03    ; 25x80, Text mode
-    int 0x10
-
-    mov ah, 0x0b    ; Change color/palette
-    mov bh, 0x00    ; Change BG color
-    mov bl, 0x01    ; Blue BG
-    int 0x10
-
-    popa
-    ret
-
-resetGraphicsMode:
-    pusha
-
-    mov ah, 0       ; Set mode
-    mov al, 0x13    ; 320x200, 256 color graphics mode
-    int 0x10
-
-    popa
-    ret

src/testing/hello.asm

@@ -1,25 +0,0 @@
-[bits 16]
-
-start:
-    mov ah, 0x0e
-    mov al, 'H'
-    int 0x10
-    mov al, 'e'
-    int 0x10
-    mov al, 'l'
-    int 0x10
-    int 0x10
-    mov al, 'o'
-    int 0x10
-    mov al, '!'
-    int 0x10
-
-    xor ax, ax
-    int 0x16
-
-    mov ax, 0x2000
-    mov ds, ax
-    mov es, ax
-    mov fs, ax
-    mov gs, ax
-    jmp 0x2000:0x0000