Separate out mouse sensitivity

ponydos.asm

@@ -11,6 +11,9 @@ org 0x7c00
 COLUMNS equ 80
 ROWS equ 25
 
+X_SENSITIVITY equ 1
+Y_SENSITIVITY equ 2
+
 jmp 0:start
 
 initialize_mouse_error:
@@ -108,9 +111,9 @@ mainloop:
 	jz .mouse_change_end
 	.mouse_change:
 		mov cx, [di - mouse_column + mouse_x]
-		shr cx, 1
+		shr cx, X_SENSITIVITY
 		mov bx, [di - mouse_column + mouse_y]
-		shr bx, 2
+		shr bx, Y_SENSITIVITY
 		mov ch, bl
 
 		call flip_mouse_cursor
@@ -412,8 +415,8 @@ Y_OVERFLOW equ 0x80
 X_OVERFLOW equ 0x40
 BUTTONS equ 0x03
 
-X_MAX_VALUE equ 2*COLUMNS-1
-Y_MAX_VALUE equ 4*ROWS-1
+X_MAX_VALUE equ (1 << X_SENSITIVITY)*COLUMNS-1
+Y_MAX_VALUE equ (1 << Y_SENSITIVITY)*ROWS-1
 
 ; in:
 ;  si = non-zero for Y
@@ -484,8 +487,7 @@ mouse_handler:
 		inc si ; will be non-zero
 		mov ax, [bp+2*8+6]
 		mov cl, 2
-		;mov dx
-		mov dl, Y_MAX_VALUE
+		mov dx, Y_MAX_VALUE
 
 		test bl, Y_OVERFLOW
 		call xy_handler