NM_RECORD_REG_OFFSET
base = (ch->dir == PCMDIR_PLAY)? NM_PLAYBACK_REG_OFFSET : NM_RECORD_REG_OFFSET;
#define NM_RECORD_ENABLE_REG (NM_RECORD_REG_OFFSET + 0)
#define NM_RBUFFER_START (NM_RECORD_REG_OFFSET + 0x4)
#define NM_RBUFFER_END (NM_RECORD_REG_OFFSET + 0x10)
#define NM_RBUFFER_WMARK (NM_RECORD_REG_OFFSET + 0xc)
#define NM_RBUFFER_CURRP (NM_RECORD_REG_OFFSET + 0x8)