1 files changed, 284 insertions, 0 deletions
diff --git a/console.asm b/console.asm
new file mode 100644
index 0000000..f992705
--- /dev/null
+++ b/console.asm
@@ -0,0 +1,284 @@
+%ifndef _CONSOLE_ASM
+%define _CONSOLE_ASM
+
+%include "constants.asm"
+%include "stdio.asm"
+%include "string.asm"
+%include "keyboard.asm"
+
+MAX_ROWS equ 25
+MAX_COLS equ 80
+
+putc:
+	; Write single character at cursor position
+	push bp
+	mov bp, sp
+	pusha
+
+	cmp al, 20h
+	jl .non_graphical
+
+	mov ah, 0ah		; BIOS - write character
+	mov bx, 00h		; video page zero
+	mov cx, 01h		; repeat character N times
+	int 10h			; BIOS video service
+
+.non_graphical:
+	push ax
+	call console_driver
+	add sp, 2
+
+	popa
+	mov sp, bp
+	pop bp
+	ret
+
+
+console_scroll_up:
+	cmp dh, MAX_ROWS - 1
+	jne .no_action
+
+	mov dh, MAX_ROWS - 2
+	push dx
+	call setcursor
+	add sp, 2
+
+	; scroll window up:
+	mov     ah, 06h ; scroll up function id.
+	mov     al, 1   ; lines to scroll.
+	mov     bx, 0700h  ; attribute for new lines.
+	mov     cl, 0   ; upper col.
+	mov     ch, 0   ; upper row.
+	mov     dl, MAX_COLS   ; lower col.
+	mov     dh, MAX_ROWS   ; lower row.
+	int     10h
+.no_action:
+	ret
+
+
+console_driver:
+	push bp
+	mov bp, sp
+
+	call console_cursor_getpos
+	mov dh, [cursor_row]
+	mov dl, [cursor_col]
+
+	mov ax, [bp + 4]
+
+.do_fn:
+.do_scancode:
+	cmp al, 00h			; when AL is 00h, check scan-code
+	jne .do_ascii
+
+	cmp ah, SC_ARROW_LEFT
+	je .handle_sc_arrow_left
+
+	cmp ah, SC_ARROW_RIGHT
+	je .handle_sc_arrow_right
+
+
+.handle_sc_arrow_left:
+	dec dl
+	jmp .return
+
+.handle_sc_arrow_right:
+	inc dl
+	jmp .return
+
+.do_ascii:
+	; ASCII control block
+	cmp al, SPC
+	jae .handle_SPC
+
+	cmp al, TAB
+	je .handle_TAB
+
+	cmp al, BS
+	je .handle_BS
+
+	cmp al, CR
+	je .handle_CR
+
+	cmp al, LF
+	je .handle_LF
+
+	; etc...
+	jmp .return
+
+
+.handle_SPC:
+	inc dl
+	cmp dl, MAX_COLS
+	jge .handle_CR
+	jmp .return
+
+.handle_TAB:
+	add dl, 4
+	jmp .return
+
+.handle_BS:
+	dec dl
+	cmp dl, 0
+	jl .skip_bs
+
+	push dx
+	call setcursor
+	add sp, 2
+
+.skip_bs:
+	mov ah, 0ah
+	mov al, 20h
+	mov bx, 00h
+	mov cx, 1
+	int 10h
+	jmp .return_noupdate
+
+.handle_CR:
+	mov dl, 0		; set column zero
+	; fall through
+
+.handle_LF:
+	inc dh			; increment row
+	jmp .return
+
+
+.return:
+	push dx
+	call setcursor
+	add sp, 2
+
+
+.return_noupdate:
+	call console_scroll_up
+	mov sp, bp
+	pop bp
+	ret
+
+
+cls:
+	push bp
+	mov bp, sp
+	pusha
+
+	mov ah, 07h		; BIOS - scroll down
+	mov al, 00h		; lines to scroll (0 == entire screen)
+	mov bx, 0700h		; color white/black
+				; & video page zero
+	mov cx, 0
+	mov dh, 24		; rows
+	mov dl, 79		; cols
+	int 10h			; BIOS video service
+	popa
+
+	mov sp, bp
+	pop bp
+	ret
+
+console_cursor_getpos:
+	push bp
+	mov bp, sp
+	pusha
+
+	mov ah, 03h		; BIOS - query cursor position and size
+	mov bh, 00h		; video page zero
+	int 10h
+
+	mov [cursor_sl_start], byte ch	; record data
+	mov [cursor_sl_end], byte cl
+	mov [cursor_row], byte dh
+	mov [cursor_col], byte dl
+
+	popa
+	mov sp, bp
+	pop bp
+	ret
+
+console_cursor_read:
+	push bp
+	mov bp, sp
+	push ax
+	push bx
+
+	mov ah, 08h		; BIOS - read character/attr at cursor
+	mov bh, 00h		; video page zero
+	int 10h
+
+	mov [cursor_attr], byte ah
+	mov [cursor_char], byte al
+
+	pop bx
+	pop ax
+	mov sp, bp
+	pop bp
+	ret
+
+console_cursor_read_last:
+	push bp
+	mov bp, sp
+	push dx
+
+	call console_cursor_getpos
+	mov dh, [cursor_row]
+	mov dl, [cursor_col]
+
+	cmp dh, 0		; is this column zero?
+	je .finalize
+
+	sub dl, 1		; previous column
+	js .prev_row		; column went negative
+	jmp .finalize
+
+.prev_row:
+	cmp dh, 0		; is this row zero?
+	je .return
+
+	sub dh, 1		; go up one row
+	add dl, 80		; return to last column of row (-1 + 80 = 79)
+
+.finalize:
+	push dx
+	call setcursor
+	call console_cursor_getpos
+	call console_cursor_read
+
+	; restore original cursor position
+	mov dh, [cursor_row]
+	mov dl, [cursor_col]
+	push dx
+	call setcursor
+.return:
+	add sp, 4
+	pop dx
+	mov sp, bp
+	pop bp
+	ret
+
+
+setcursor:
+	push bp
+	mov bp, sp
+	pusha
+
+	mov ah, 02h		; BIOS - set cursor position
+	mov bh, 0		; video page zero
+	mov dx, [bp + 4]	; address of new cursor value
+	int 10h			; BIOS video service
+
+	popa
+	mov sp, bp
+	pop bp
+	ret
+
+
+; data
+cursor_sl_start: db 0
+cursor_sl_end: db 0
+cursor_row: db 0
+cursor_col: db 0
+cursor_row_vram: dw 0
+cursor_col_vram: dw 0
+cursor_vram: dw 0
+cursor_attr: db 0
+cursor_char: db 0
+%endif