BASIC interpreter

data/hello.bas

@@ -1,2 +1,4 @@
-PRINT "Hello World!"
+FOR A = 1 TO 10
+PRINT A
+NEXT A
 END

source/kernel/data.asm

@@ -40,6 +40,7 @@ command_result_text: db 'You typed: ', 0
 unknown_command: db 'Error: Unkown Command..\n ', 0
 stringified_int: db 0,0,0,0,0,0 ; Can store up to 6 digits
 
+int_tmp: dw 0
 ; Disk operations
 disk_read_fail: db 'Error: Could not read disk\n', 0
 file_not_found: db 'File not found\n', 0
@@ -59,3 +60,4 @@ read_write_flag: db 02
 empty_byte: db 0
 empty_word: dw 0
 empty_dword: dd 0
+tmp: db '97', 0

source/kernel/features/basic.asm

@@ -318,7 +318,6 @@ clear_ram:
 assign:
 	cmp ax, VARIABLE			; Are we starting with a number var?
 	je .do_num_var
-
 	mov di, string_vars			; Otherwise it's a string var
 	mov ax, 128
 	mul bx					; (BX = string number, passed back from get_token)

source/kernel/features/cli.asm

@@ -17,7 +17,7 @@ os_start_cli:
 
 os_read_cli:
 	pusha
-	mov si, user_input
+	mov ax, user_input
 	call string_upper_case ; Make the input uppercase so it's case insensitive
 
 .output_the_user_input:

source/kernel/features/disk.asm

@@ -308,6 +308,7 @@ disk_write_file:
 ; OUT
 ; output_buffer: the list (string)
 disk_list_contents:
+	call disk_load_root
 	pusha
 	mov si, root_buffer
 	mov di, output_buffer
@@ -322,38 +323,22 @@ disk_list_contents:
 			dec cx
 			cmp cx, 0
 			jne .space_loop
-
+		mov ax, [si+28d]
-		.file_attribute:
+		call string_cast_from_int
-			add si, 11d
-			lodsb
 		push si
-
+		mov si, stringified_int
-			mov si, read_only
+		lodsb
-			cmp al, 1h
+		.output_file_size_loop:
-			je .add_string
+			stosb
-			mov si, hidden
+			lodsb
-			cmp al, 2h
+			cmp al, 0
-			je .add_string
+			jne .output_file_size_loop
-			mov si, system
+		.after_fs_loop:
-			cmp al, 4h
-			je .add_string
-			mov si, volume
-			cmp al, 8h
-			je .add_string
-			mov si, directory
-			cmp al, 10h
-			je .add_string
-			mov si, archive
-			cmp al, 20h
-			je .add_string
-
-		.after_file_attributes:
 		pop si
-
 		mov al, 0Ah
 		stosb
 
-		add si, 20d
+		add si, 20h
 		lodsb ; +1
 		dec si ; -1
 		cmp al, 0 ; You've come to the end of the root entries
@@ -361,13 +346,6 @@ disk_list_contents:
 		cmp al, 00E5h	; E5h is a marker that the Fat entry is available
 		je .finish
 		jmp .loop
-	.add_string:
-		.add_string_loop:
-			lodsb
-			cmp ax, 00h
-			je .after_file_attributes
-			stosb
-			jmp .add_string_loop
 	.finish:
 		mov cx, output_buffer
 		sub di, cx

source/kernel/features/strings.asm

@@ -107,89 +107,84 @@ string_join:
 
 ; ------------------------------------------------------------------------
 ; TODO
+; Converts a null terminated string to an integer
+; IN: SI = string location (max 5 chars, up to '65536')
+; OUT: AX = number
 string_cast_to_int:
+	pusha
+	xor cx,cx
+	.loop:
+		xor ax,ax
+		lodsb
+		cmp al, 0
+		je .finish
+		sub al, 30h
+		mov bx, ax
+		mov ax, 10
+		mul cx ; Multiple the current value by 10
+		add ax, bx ; Then add the new digit
+		mov cx, ax
+		jmp .loop
+	.finish:
+		mov [int_tmp], cx
+		popa
+		mov ax, [int_tmp]
 		ret
 
 ; ------------------------------------------------------------------------
+; IN:  AX = integer (unsigned)
+; OUT: AX -> null-terminated string
 
-; IN: AX = int
+string_cast_from_int:
-; OUT: AX = string location (output buffer)
-string_cast_from_int: ; TODO I think this algorithm could be optimised
 	pusha
-	; Initialise base to decimal (base 10)
+	cld ; Write backwards
-	mov bx, 10
-	; clear the strigified int location
-	mov cx, 6
-	push ax
-	xor ax,ax
-	.clear_loop:
-		stosb
-		dec cx
-		cmp cx, 0
-		ja .clear_loop
-	; setup
-	pop ax
-	push ax
-	mov cx, -1
-	; loop over number to get the value of count (cx)
-	.count_loop:
-		xor dx,dx
-		div bx ; ax = ax // bx
-		inc cx
-		cmp ax, 0
-		ja .count_loop ; Jump if greater
-	pop ax
-	; loop over count downwards until count is 0
 	mov di, stringified_int
-	.stringify_loop:
+
-		mov cx,1 ;DEL
+	mov bx, 10			; base
-		push cx
+	mov cx, 0			; digit count
-		push bx
+
-		push ax
+	.convert_loop:
-		; Generate power of 10
+		xor dx, dx
-		mov ax, 1
+		div bx				; AX = AX / base, DX = remainder
-		mov cx,0 ;DEL
+		add dl, '0'
-		cmp cx, 1
+		push dx				; store digit
-		jl .after_power_loop
+		inc cx
-		.power_loop:
+		test ax, ax
-			mul bx
+		jnz .convert_loop
-			dec cx
+
-			cmp cx, 0
+	.write_loop:
-			ja .power_loop
-		.after_power_loop:
-		mov bx,ax
 		pop ax
-		pop cx
-		; ax = ax DIV bx
-		; dx = ax MOD bx
-		xor dx,dx
-		div bx
-		pop bx
-		add ax, 30h
 		stosb
-		mov ax, dx
+		loop .write_loop
-		dec cx
+
-		cmp cx, 0
+		mov al, 0
-		ja .stringify_loop
+		stosb				; null terminator
-	.finish:
+
 		popa
-		;mov ax, stringified_int
+		mov ax, stringified_int
 		ret
 
+;----------------------------------------------------------------------------
+
 ; Get the length of a string
 ; 'hello world', 0 is 11 characters long (excluding the terminator)
-; input: si points to the string to be counted
+; input: ax points to the string to be counted
-; output: cl holds the length
+; output: ax holds the length
 string_length:
    push si
-   xor cl,cl ; Clear the al register
+   push cx
+   mov si, ax
+   xor ax,ax ; Clear the cx register
+   xor cx,cx
 .loop:
    lodsb
    cmp al, 0
    je .finish
-   inc cl
+   inc cx
    jmp .loop
 .finish:
+	mov ax, cx
+	pop cx
    pop si
    ret
 
@@ -204,7 +199,9 @@ string_length:
 os_format_fat_filename:
 	pusha
 	call string_upper_case
+	mov ax, si
 	call string_length ; Stores the length of the string in cl
+	mov cl, al
 	xor ch,ch ; Clear ch to reset it to 0
 	.character_loop:
 	  lodsb
@@ -287,12 +284,15 @@ string_unformat_fat_filename:
 		popa
 		ret
 
+; -------------------------------------------------------------------------------------
+
 ; Convert a string to all upper/lower case
-; INPUT: si pointing to a string
+; INPUT: ax pointing to a string
 ; OUPUT: the same string in memory will now be capitalised/decapitalised
 string_upper_case: ; to upper case
 	pusha
-    mov di, si
+	mov si,ax
+	mov di,si 
 .loop:
 	lodsb ; Load the character into al
 	inc di
@@ -310,8 +310,9 @@ string_upper_case: ; to upper case
 	popa
 	ret
 
-os_lower_case: ; to lower case
+string_lower_case: ; to lower case
 	pusha
+	mov si, ax
 	mov di, si
 .loop:
 	lodsb ; Load the character into al
@@ -330,8 +331,6 @@ os_lower_case: ; to lower case
 	popa
 	ret
 
-string_lower_case:
-	ret
 string_input:
 	ret
 string_print_2hex:

source/kernel/features/utils.asm

@@ -17,7 +17,6 @@ util_cat:
 util_ls:
    pusha
 
-   call disk_load_root
    call disk_list_contents
 
    mov si, output_buffer

source/kernel/kernel.asm

@@ -11,11 +11,9 @@ start:
    mov si, boot_message
    call os_print_string
 
-   ; TESTING
+	mov si, tmp
-   ;mov ax, 3
+	mov ah, 0Eh
-   ;call string_cast_from_int
+	int 10h
-   ;mov si, stringified_int
-   ;call os_print_string
 
    call os_start_cli
    hlt

test-linux.sh

@@ -4,8 +4,8 @@ sudo make
 sudo chown $(whoami) disk_images/*
 qemu-system-i386\
 	-drive file=disk_images/crawos.img,if=floppy,format=raw\
-	-m 512m\
+	-m 8m\
-	-object memory-backend-file,id=pc.ram,size=512m,mem-path=/dev/shm/qemu-ram,share=on\
+	-object memory-backend-file,id=pc.ram,size=8m,mem-path=/dev/shm/qemu-ram,share=on\
 	-machine memory-backend=pc.ram\
 	-d in_asm,int -D ./detailed.log\
 	$1 $2