MFP_IERA
mfp_base[MFP_IERA] = ((u_int8_t) (a))
#define mfp_get_iera() (mfp_base[MFP_IERA])
#define mfp_bit_set_iera(bits) mfp_bit_set(MFP_IERA, (bits))
#define mfp_bit_clear_iera(bits) mfp_bit_clear(MFP_IERA, (bits))