EMU_CHAN_PTRX
emu_wrptr(sc, ch, EMU_CHAN_PTRX, 0);
emu_wrptr(sc, ch, EMU_CHAN_PTRX, 0);
emu_wrptr(sc, v->vnum, EMU_CHAN_PTRX, (x << 8) | r);
emu_wrptr(sc, v->vnum, EMU_CHAN_PTRX, (v->amounts[0] << 8) | (v->amounts[1] << 0));
emu_wrptr(sc, ch, EMU_CHAN_PTRX, 0);
emu_wrptr(sc, ch, EMU_CHAN_PTRX, 0);
#define EMU_CHAN_PTRX_PITCHTARGET EMU_MKSUBREG(16, 16, EMU_CHAN_PTRX)
#define EMU_CHAN_PTRX_FXSENDAMOUNT_A EMU_MKSUBREG(8, 8, EMU_CHAN_PTRX)
#define EMU_CHAN_PTRX_FXSENDAMOUNT_B EMU_MKSUBREG(8, 0, EMU_CHAN_PTRX)