/// (Ex9E) Skip next instruction if key with value Vx pressed.
(Ex9E) Skip next instruction if key with value Vx pressed.
( Ex9E ) Skip next instruction if key with value Vx pressed .
fn opcode_skp(&mut self) {
        let vx = self.v_reg[self.opcode.x()];
        if self.keypad[vx as usize] == 1 {
            self.pc += 2;
        }
        self.pc += 2;
    }
fn opcode_skp ( & mut self ) { let vx = self . v_reg [ self . opcode . x ( ) ] ; if self . keypad [ vx as usize ] == 1 { self . pc += 2 ; } self . pc += 2 ; }
(Ex9E) Skip next instruction if key with value Vx pressed.
( Ex9E ) Skip next instruction if key with value Vx pressed .
&mut self