also, there is key_force.x and key_force.y. Key_force.x will return a 1 or a -1 if the left/right keys are pressed and return a zero if no arrow key is pressed.

for example,
my.speedY = 5 * (key_cul - key_cur);
becomes
my.speedY = 5 * key_force.x.

key_force.y works the same way with the up/down

there is also mouse_force.x and mouse_force.y which works the same way and is a good way to make the player turn via the mouse.