Split of LAPDm into a core part and a GSM specific part
Instead of mixing together the GSM layer 1 interface and RSL interface
with the implementation of LAPD, the core function of LAPD is now
extracted from LAPDm. The core implementation is now in lapd_core.c
and lapd_core.h respectively.
The lapd_core.c implements exactly one datalink instance for one SAP.
The surrounding implementation "lapdm.c" codes/decodes the layer 2
headers and handles multiplexing and datalink instances, as well as
translates primitives from/to RSL layer.
lapd_core.c can now be used for other LAPD implementations. (ISDN/ABIS)
diff --git a/include/osmocom/gsm/lapd_core.h b/include/osmocom/gsm/lapd_core.h
new file mode 100644
index 0000000..0f4e889
--- /dev/null
+++ b/include/osmocom/gsm/lapd_core.h
@@ -0,0 +1,171 @@
+#ifndef _OSMOCOM_LAPD_H
+#define _OSMOCOM_LAPD_H
+
+#include <stdint.h>
+
+#include <osmocom/core/timer.h>
+#include <osmocom/core/msgb.h>
+#include <osmocom/gsm/prim.h>
+
+/*! \defgroup lapd LAPD implementation common part
+ * @{
+ */
+
+/*! \file lapd.h */
+
+/* primitive related sutff */
+
+/*! \brief LAPD related primitives (L2<->L3 SAP)*/
+enum osmo_dl_prim {
+ PRIM_DL_UNIT_DATA, /*!< \brief DL-UNIT-DATA */
+ PRIM_DL_DATA, /*!< \brief DL-DATA */
+ PRIM_DL_EST, /*!< \brief DL-ESTABLISH */
+ PRIM_DL_REL, /*!< \brief DL-RLEEASE */
+ PRIM_DL_SUSP, /*!< \brief DL-SUSPEND */
+ PRIM_DL_RES, /*!< \brief DL-RESUME */
+ PRIM_DL_RECON, /*!< \brief DL-RECONNECT */
+ PRIM_MDL_ERROR, /*!< \brief MDL-ERROR */
+};
+
+/* Uses the same values as RLL, so no conversion for GSM is required. */
+#define MDL_CAUSE_T200_EXPIRED 0x01
+#define MDL_CAUSE_REEST_REQ 0x02
+#define MDL_CAUSE_UNSOL_UA_RESP 0x03
+#define MDL_CAUSE_UNSOL_DM_RESP 0x04
+#define MDL_CAUSE_UNSOL_DM_RESP_MF 0x05
+#define MDL_CAUSE_UNSOL_SPRV_RESP 0x06
+#define MDL_CAUSE_SEQ_ERR 0x07
+#define MDL_CAUSE_UFRM_INC_PARAM 0x08
+#define MDL_CAUSE_SFRM_INC_PARAM 0x09
+#define MDL_CAUSE_IFRM_INC_MBITS 0x0a
+#define MDL_CAUSE_IFRM_INC_LEN 0x0b
+#define MDL_CAUSE_FRM_UNIMPL 0x0c
+#define MDL_CAUSE_SABM_MF 0x0d
+#define MDL_CAUSE_SABM_INFO_NOTALL 0x0e
+#define MDL_CAUSE_FRMR 0x0f
+
+/*! \brief for MDL-ERROR.ind */
+struct mdl_error_ind_param {
+ uint8_t cause; /*!< \brief generic cause value */
+};
+
+/*! \brief for DL-REL.req */
+struct dl_rel_req_param {
+ uint8_t mode; /*!< \brief release mode */
+};
+
+/*! \brief primitive header for LAPD DL-SAP primitives */
+struct osmo_dlsap_prim {
+ struct osmo_prim_hdr oph; /*!< \brief generic primitive header */
+ union {
+ struct mdl_error_ind_param error_ind;
+ struct dl_rel_req_param rel_req;
+ } u; /*!< \brief request-specific data */
+};
+
+/*! \brief LAPD mode/role */
+enum lapd_mode {
+ LAPD_MODE_USER, /*!< \brief behave like user */
+ LAPD_MODE_NETWORK, /*!< \brief behave like network */
+};
+
+/*! \brief LAPD state (Figure B.2/Q.921)*/
+enum lapd_state {
+ LAPD_STATE_NULL = 0,
+ LAPD_STATE_TEI_UNASS,
+ LAPD_STATE_ASS_TEI_WAIT,
+ LAPD_STATE_EST_TEI_WAIT,
+ LAPD_STATE_IDLE,
+ LAPD_STATE_SABM_SENT,
+ LAPD_STATE_DISC_SENT,
+ LAPD_STATE_MF_EST,
+ LAPD_STATE_TIMER_RECOV,
+};
+
+/*! \brief LAPD message format (I / S / U) */
+enum lapd_format {
+ LAPD_FORM_UKN = 0,
+ LAPD_FORM_I,
+ LAPD_FORM_S,
+ LAPD_FORM_U,
+};
+
+/*! \brief LAPD message context */
+struct lapd_msg_ctx {
+ struct lapd_datalink *dl;
+ int n201;
+ /* address */
+ uint8_t cr;
+ uint8_t sapi;
+ uint8_t tei;
+ uint8_t lpd;
+ /* control */
+ uint8_t format;
+ uint8_t p_f; /* poll / final bit */
+ uint8_t n_send;
+ uint8_t n_recv;
+ uint8_t s_u; /* S or repectivly U function bits */
+ /* length */
+ int length;
+ uint8_t more;
+};
+
+struct lapd_cr_ent {
+ uint8_t cmd;
+ uint8_t resp;
+};
+
+struct lapd_history {
+ struct msgb *msg; /* message to be sent / NULL, if histoy is empty */
+ int more; /* if message is fragmented */
+};
+
+/*! \brief LAPD datalink */
+struct lapd_datalink {
+ int (*send_dlsap)(struct osmo_dlsap_prim *dp,
+ struct lapd_msg_ctx *lctx);
+ int (*send_ph_data_req)(struct lapd_msg_ctx *lctx, struct msgb *msg);
+ struct {
+ /*! \brief filled-in once we set the lapd_mode above */
+ struct lapd_cr_ent loc2rem;
+ struct lapd_cr_ent rem2loc;
+ } cr;
+ enum lapd_mode mode; /*!< \brief current mode of link */
+ int use_sabme; /*!< \brief use SABME instead of SABM */
+ int reestablish; /*!< \brief enable reestablish support */
+ int n200, n200_est_rel; /*!< \brief number of retranmissions */
+ struct lapd_msg_ctx lctx; /*!< \brief LAPD context */
+ int maxf; /*!< \brief maximum frame size (after defragmentation) */
+ uint8_t k; /*!< \brief maximum number of unacknowledged frames */
+ uint8_t v_range; /*!< \brief range of sequence numbers */
+ uint8_t v_send; /*!< \brief seq nr of next I frame to be transmitted */
+ uint8_t v_ack; /*!< \brief last frame ACKed by peer */
+ uint8_t v_recv; /*!< \brief seq nr of next I frame expected to be received */
+ uint32_t state; /*!< \brief LAPD state (\ref lapd_state) */
+ int seq_err_cond; /*!< \brief condition of sequence error */
+ uint8_t own_busy; /*!< \brief receiver busy on our side */
+ uint8_t peer_busy; /*!< \brief receiver busy on remote side */
+ int t200_sec, t200_usec; /*!< \brief retry timer (default 1 sec) */
+ int t203_sec, t203_usec; /*!< \brief retry timer (default 10 secs) */
+ struct osmo_timer_list t200; /*!< \brief T200 timer */
+ struct osmo_timer_list t203; /*!< \brief T203 timer */
+ uint8_t retrans_ctr; /*!< \brief re-transmission counter */
+ struct llist_head tx_queue; /*!< \brief frames to L1 */
+ struct llist_head send_queue; /*!< \brief frames from L3 */
+ struct msgb *send_buffer; /*!< \brief current frame transmitting */
+ int send_out; /*!< \brief how much was sent from send_buffer */
+ struct lapd_history *tx_hist; /*!< \brief tx history structure array */
+ uint8_t range_hist; /*!< \brief range of history buffer 2..2^n */
+ struct msgb *rcv_buffer; /*!< \brief buffer to assemble the received message */
+ struct msgb *cont_res; /*!< \brief buffer to store content resolution data on network side, to detect multiple phones on same channel */
+};
+
+void lapd_dl_init(struct lapd_datalink *dl, uint8_t k, uint8_t v_range,
+ int maxf);
+void lapd_dl_exit(struct lapd_datalink *dl);
+void lapd_dl_reset(struct lapd_datalink *dl);
+int lapd_set_mode(struct lapd_datalink *dl, enum lapd_mode mode);
+int lapd_ph_data_ind(struct msgb *msg, struct lapd_msg_ctx *lctx);
+int lapd_recv_dlsap(struct osmo_dlsap_prim *dp, struct lapd_msg_ctx *lctx);
+
+#endif /* _OSMOCOM_LAPD_H */