Starting writing an ed implementation

source/kernel/programs/ed.asm

@@ -0,0 +1,35 @@
+; Planned commands:
+; i insert
+; a append
+; l prints lines
+; w save to disk
+; q quit
+ed:
+	pusha
+	mov si, ed_welcome
+	call os_print_string
+	.main_loop:
+		mov ax, ed_prompt
+		mov bx, 40
+		call keyboard_display_input ; AX = string location, BX = max prompt length
+		mov si, ed_prompt
+		jmp .get_token
+
+	; Types of tokens:
+	; Number: eg 123
+	; Doller (refers to the last line) $
+	; Comma ,
+	; Command: eg i
+	; 123
+	.get_token:
+		xor ax,ax
+		lodsb
+		call check_is_number
+		jmp .exit
+
+	.exit:
+		popa
+		ret
+
+ed_prompt:	times 40 db 0
+ed_welcome: db "This is ED\n", 0