ESRC_IREGS
out = eap1371_src_read(sc, ESRC_ADC+ESRC_IREGS) & 0xff;
eap1371_src_write(sc, ESRC_ADC+ESRC_IREGS, out |
r = eap1371_src_read(sc, dac + ESRC_IREGS) & 0x00ff;
eap1371_src_write(sc, dac + ESRC_IREGS, r | ((freq >> 5) & 0xfc00));
eap1371_src_write(sc, ESRC_DAC1+ESRC_IREGS, ESRC_SET_VFI(16));
eap1371_src_write(sc, ESRC_DAC2+ESRC_IREGS, ESRC_SET_VFI(16));