请问CYPRESS的USB芯片固件问题

在固件程序里（芯片为CY7C63723）有这么一段语句，不是很明白。请大虾指教。谢谢！
#pragma portrw USB_STATUS @ 0x1F; /*  USB upstream status and control */
#define VREG_ENABLE_MASK (1 << 6)
#define PS2_PULLUP_MASK (1 << 7)
#define PS2_INTERRUPT_MODE_MASK (1 << 5)
#define BUS_ACTIVITY_MASK (1 << 3)
#define BUS_ACTIVITY 3
#define NOT_FORCING             0b000
#define FORCE_K                 0b001
#define FORCE_J                 0b010
#define FORCE_SE0               0b011
#define FORCE_NEG_LOW_POS_OPEN  0b101
#define FORCE_NEG_OPEN_POS_LOW  0b110
#define FORCE_NEG_OPEN_POS_OPEN 0b111