Disk reading partly done
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@@ -17,6 +17,8 @@ os_start_cli:
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os_read_cli:
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pusha
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mov si, user_input
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call os_upper_case ; Make the input uppercase so it's case insensitive
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.output_the_user_input:
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call os_print_newline
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@@ -0,0 +1,175 @@
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; Reset the disk system using int 13h / AH = 00h
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disk_reset:
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pusha
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stc
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mov ah, 00h
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int 13h
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popa
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ret
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; ------------------------------------
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; Load the root directory into memory (into disk_buffer which is 24000h)
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disk_load_root:
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pusha
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mov ax, 19 ; First sector of root entry
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call math_lba_to_chs ; Assigns ch, cl and dh the correct values
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xor ax,ax
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mov dl, [ebr_drive_number] ; Drive number
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mov ah, 02h ; BIOS ah code for read disk sectors to memory
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mov al, 0Ch ; Root directory has 12 sectors
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mov si, root_buffer ; ES:BX should point to our buffer
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mov bx, si
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; repeat drive read 3 times (incase of random error)
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mov di, 3 ; counter
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; This is basically
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; for di in range(3,1,1):
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; We test to see if we can read the disk 3 times
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.try_read_disk: ; Try read the floppy three times
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; When the disk is tried to be read, the CF flag will be
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; set if there's an error, so we just clear it to return it to
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; the default state
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stc ; sets the cf flag
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int 13h
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jnc .done_read ; jump if cf = 0
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call disk_reset ; Reset drivers of disk
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dec di ; di -= 1
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test di, di ; if di = 0
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jnz .try_read_disk
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jmp .disk_error
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.disk_error:
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mov si, disk_read_fail
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call os_print_string
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popa
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ret
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.done_read:
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popa
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ret
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; ---------------------------------------------
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; Reads a certain number of sectors into memory
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; int 13h/ah = 02h read disk sectors into memory
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; al = number of sectors to read
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; ch = cylinder number
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; cl = sector number
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; dh = head number
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; dl = drive number
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; es:bx = points to data buffer
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disk_read:
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push ax
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push bx
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push cx
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push dx
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push di
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; cl = sector
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; ch = cylinder
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; dh = head
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; dl = drive
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call math_lba_to_chs ; Get the chs address
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mov ah, 02h ; BIOS ah code for read disk sectors to memory
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; repeat drive read 3 times (incase of random error)
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mov di, 3 ; counter
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; This is basically
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; for di in range(3,1,1):
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; We test to see if we can read the disk 3 times
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.retry:
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; When the disk is tried to be read, the CF flag will be
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; set if there's an error, so we just clear it to return it to
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; the default state
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stc ; sets the cf flag
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int 13h
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jnc .done_read ; jump if cf = 0
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call .disk_reset ; Reset drivers of disk
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dec di ; di -= 1
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test di, di ; if di = 0
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jnz .retry
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.fail_disk_read:
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pop di
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pop dx
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pop cx
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pop bx
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pop ax
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ret
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; int 13h / ah = 00h reset disk system
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.disk_reset:
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pusha
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mov ah, 0 ; Reset drive
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stc
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int 13h
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jc .fail_disk_read
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popa
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ret
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.done_read:
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pop di
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pop dx
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pop cx
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pop bx
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pop ax
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ret
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; -------------------------------------
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disk_load_file:
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pusha
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mov di, fat12_file_name
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call os_format_fat_filename
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; Prepare values
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mov si, root_buffer
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xor bx,bx
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.search_root:
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mov di, fat12_file_name ; Move the name of the kernel into di
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mov cx, 11 ; length of 'KERNEL BIN'
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push si ; Preserve si
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repe cmpsb ; Repeat a comparison of bytes between file name and current bytes until it finds a match
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pop si ; Retrieve si
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je .found_file
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add si, 32 ; increment di to the next directory entry
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inc bx
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cmp bx, [bdb_dir_entries_count] ; Have we reached the number of directories that exist
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jl .search_root ; Repeat search
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jmp .file_not_found ; If the last dir has been searched, then there is no kernel
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.found_file:
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mov ax, [si+26] ; ax is now a pointer to the pointer to the file relative to the data segments :D
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add ax, 20h
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mov [file_cluster], ax
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; Setup registers for disk read
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mov bx, data_buffer
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mov dl, [ebr_drive_number]
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call disk_read ; Load file from disk into memory
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jmp .done
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.file_not_found:
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mov si, file_not_found
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call os_print_string
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jmp .done
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.done:
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popa
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ret
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section .data:
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disk_read_fail: db 'Error: Could not read disk\n', 0
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file_not_found: db 'File not found\n', 0
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file_found: db 'File found\n', 0
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loading_root: db 'Loading root diretory\n', 0
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file_cluster: dw 0
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fat12_file_name: db ' '
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@@ -5,6 +5,7 @@
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; H = T % heads
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; C = T / headers
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; input, LBA index: ax
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; ouput:
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; sector number: cl
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; cylinder: ch
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; head: dh
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@@ -29,7 +30,7 @@
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; cylinder (ch) = 02h
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; head (cl) = 00h
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; sector (dh) = 09h
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os_lba_to_chs:
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math_lba_to_chs:
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push ax
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push dx
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@@ -48,6 +48,31 @@ os_print_string:
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popa
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ret
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; This is similar to the previous, however it prints
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; raw output (including null) and prints the number
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; of character defined by ax
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; IN:
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; SI = pointer to start of string to be printed
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; AX = Length of string to print
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text_raw_output:
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pusha
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mov di, ax
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mov ah, 0Eh ; int 10h teletype function, we're telling the BIOS we will print something
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.repeat:
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lodsb ; Get char from si into al
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int 10h ; Otherwise, print it
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dec di
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cmp di, 00h
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je .done
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jne .repeat
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.done:
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popa
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ret
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; --------------------------------------------
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os_print_newline:
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@@ -48,24 +48,24 @@ game_pong:
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mov dx, [p1_y]
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sub dx, 5
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mov [p1_y], dx
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jmp .detect_input
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ret
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.p1_down:
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mov dx, [p1_y]
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add dx, 5
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mov [p1_y], dx
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jmp .detect_input
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ret
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; Player 2 movements
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.p2_up:
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mov dx, [p2_y]
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sub dx, 5
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mov [p2_y], dx
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jmp .detect_input
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ret
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.p2_down:
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mov dx, [p2_y]
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add dx, 5
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mov [p2_y], dx
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jmp .detect_input
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ret
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; Ball bouncing
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; This should move the ball along one frame
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@@ -97,17 +97,17 @@ game_pong:
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; Player 1
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cmp al, 77h ; Pressed 'w' (player 1 up)
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je .p1_up
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call .p1_up
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cmp al, 73h ; Pressed 's' (player 1 down)
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je .p1_down
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call .p1_down
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; Player 2
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cmp al, 5bh ; Pressed '[' (player 2 up)
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je .p2_up
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call .p2_up
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cmp al, 27h ; Pressed ''' (player 2 down)
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je .p2_down
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call .p2_down
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call .bounce_ball
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;call .bounce_ball
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call .draw_screen
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jmp .detect_input
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@@ -1,12 +1,17 @@
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ORG 0h
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ORG 00h
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BITS 16
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root_buffer equ 24000h
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data_buffer equ 26000h
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start:
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mov si, boot_message
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call os_print_string
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mov si, help_text
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call os_print_string
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call disk_load_root ; Loads the root directory into disk_buffer
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; Physical address = (segment * 16) + offset
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mov si, file_name
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call disk_load_file
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call os_start_cli
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hlt
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@@ -14,7 +19,31 @@ start:
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halt:
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jmp halt
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boot_message: db 'OK] Kernel successfully loaded!\n', 0
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boot_message: db 'OK] Kernel successfully loaded!\n\n', 0
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file_name: db 'hello.cws', 0
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; Define Fat12 header
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bdb_oem: db 'MSWIN4.1' ; ignore
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bdb_bytes_per_sector: dw 200h ; = 512d
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bdb_sectors_per_cluster: db 01h ; sector = cluster
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bdb_reserved_sectors: dw 01h
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bdb_fat_count: db 02h ; We've got a fat1 and fat2
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bdb_dir_entries_count: dw 0E0h ; Maximum number of root directory entries
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bdb_total_sectors: dw 0B40h ; = 2880d
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bdb_media_descriptor_type: db 0F0h ; ignore
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bdb_sectors_per_fat: dw 09h
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bdb_sectors_per_track: dw 12h ; = 18d
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bdb_number_of_heads: dw 02h ; top and bottom of the floppy disk
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bdb_hidden_sectors: dd 0 ; ignore
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bdb_large_sector_count: dd 0 ; total sector count for fat32 (0 for fat12 or fat16)
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; extended boot record
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ebr_drive_number: db 0 ; ignore
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db 0 ; ignore
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ebr_signature: db 29h ; boot signature, indicates that the next three fields are present (0x29)
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ebr_volume_id: db 12h, 34h, 56h, 78h ; unique id for volume tracking
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ebr_volume_label: db 'CrawShaw OS' ; must be 11 bytes
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ebr_system_id: db 'FAT12 ' ; must be 8 bytes
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; ------------------------------------------------------------------
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; FEATURES -- Code to pull into the kernel
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@@ -25,5 +54,8 @@ boot_message: db 'OK] Kernel successfully loaded!\n', 0
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%INCLUDE "source/kernel/features/strings.asm"
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%INCLUDE "source/kernel/features/graphics.asm"
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%INCLUDE "source/kernel/features/disk.asm"
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%INCLUDE "source/kernel/features/math.asm"
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; GAMES -- Games that I wrote for it
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%INCLUDE "source/kernel/games/pong.asm"
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