/* xdlc.h
 * Define *DLC frame types, and routine to dissect the control field of
 * a *DLC frame.
 *
 * $Id: xdlc.h 27217 2009-01-13 06:54:06Z guy $
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

#ifndef __XDLC_H__
#define __XDLC_H__

/*
 * Low-order bits of first (extended) or only (basic) octet of control
 * field, specifying the frame type.
 */
#define XDLC_I_MASK		0x01	/* Mask to test for I or not I */
#define XDLC_I			0x00	/* Information frames */
#define XDLC_S_U_MASK		0x03	/* Mask to test for S or U */
#define XDLC_S			0x01	/* Supervisory frames */
#define XDLC_U			0x03	/* Unnumbered frames */

/*
 * N(S) and N(R) fields, in basic and extended operation.
 */
#define XDLC_N_R_MASK		0xE0	/* basic */
#define XDLC_N_R_SHIFT		5
#define XDLC_N_R_EXT_MASK	0xFE00	/* extended */
#define XDLC_N_R_EXT_SHIFT	9
#define XDLC_N_S_MASK		0x0E	/* basic */
#define XDLC_N_S_SHIFT		1
#define XDLC_N_S_EXT_MASK	0x00FE	/* extended */
#define XDLC_N_S_EXT_SHIFT	1

/*
 * Poll/Final bit, in basic and extended operation.
 */
#define XDLC_P_F	0x10	/* basic */
#define XDLC_P_F_EXT	0x0100	/* extended */

/*
 * S-format frame types.
 */
#define XDLC_S_FTYPE_MASK	0x0C
#define XDLC_RR			0x00	/* Receiver ready */
#define XDLC_RNR		0x04	/* Receiver not ready */
#define XDLC_REJ		0x08	/* Reject */
#define XDLC_SREJ		0x0C	/* Selective reject */

/*
 * U-format modifiers.
 */
#define XDLC_U_MODIFIER_MASK	0xEC
#define XDLC_UI		0x00	/* Unnumbered Information */
#define XDLC_UP		0x20	/* Unnumbered Poll */
#define XDLC_DISC	0x40	/* Disconnect (command) */
#define XDLC_RD		0x40	/* Request Disconnect (response) */
#define XDLC_UA		0x60	/* Unnumbered Acknowledge */
#define XDLC_SNRM	0x80	/* Set Normal Response Mode */
#define XDLC_TEST	0xE0	/* Test */
#define XDLC_SIM	0x04	/* Set Initialization Mode (command) */
#define XDLC_RIM	0x04	/* Request Initialization Mode (response) */
#define XDLC_FRMR	0x84	/* Frame reject */
#define XDLC_CFGR	0xC4	/* Configure */
#define XDLC_SARM	0x0C	/* Set Asynchronous Response Mode (command) */
#define XDLC_DM		0x0C	/* Disconnected mode (response) */
#define XDLC_SABM	0x2C	/* Set Asynchronous Balanced Mode */
#define XDLC_SARME	0x4C	/* Set Asynchronous Response Mode Extended */
#define XDLC_SABME	0x6C	/* Set Asynchronous Balanced Mode Extended */
#define XDLC_RESET	0x8C	/* Reset */
#define XDLC_XID	0xAC	/* Exchange identification */
#define XDLC_SNRME	0xCC	/* Set Normal Response Mode Extended */
#define XDLC_BCN	0xEC	/* Beacon */

/*
 * This macro takes the control field of an xDLC frame, as returned by
 * "get_xdlc_control()" or "dissect_xdlc_control()", and evaluates to
 * TRUE if the frame is an "information" frame and FALSE if it isn't.
 * Note that frames other than information frames can have data in them,
 * e.g. TEST frames.
 */
#define XDLC_IS_INFORMATION(control) \
	(((control) & XDLC_I_MASK) == XDLC_I || (control) == (XDLC_UI|XDLC_U))

/*
 * This macro takes the control field of an xDLC frame, and a flag saying
 * whether we're doing basic or extended operation, and evaluates to
 * the length of that field (if it's an Unnumbered frame, or we're not
 * in extended mode, it's 1 byte long, otherwise it's 2 bytes long).
 */
#define XDLC_CONTROL_LEN(control, is_extended) \
	((((control) & XDLC_S_U_MASK) == XDLC_U || !(is_extended)) ? 1 : 2)

/*
 * Structure containing pointers to hf_ values for various subfields of
 * the control field.
 */
typedef struct {
	int	*hf_xdlc_n_r;
	int	*hf_xdlc_n_s;
	int	*hf_xdlc_p;
	int	*hf_xdlc_f;
	int	*hf_xdlc_s_ftype;
	int	*hf_xdlc_u_modifier_cmd;
	int	*hf_xdlc_u_modifier_resp;
	int	*hf_xdlc_ftype_i;
	int	*hf_xdlc_ftype_s_u;
} xdlc_cf_items;

extern const value_string ftype_vals[];
extern const value_string stype_vals[];
extern const value_string modifier_vals_cmd[];
extern const value_string modifier_vals_resp[];

extern int get_xdlc_control(const guchar *pd, int offset, gboolean is_extended);

/*
 * Check whether the control field of the packet looks valid.
 */
extern gboolean check_xdlc_control(tvbuff_t *tvb, int offset,
  const value_string *u_modifier_short_vals_cmd,
  const value_string *u_modifier_short_vals_resp, gboolean is_response,
  gboolean is_extended _U_);

extern int dissect_xdlc_control(tvbuff_t *tvb, int offset, packet_info *pinfo,
  proto_tree *xdlc_tree, int hf_xdlc_control, gint ett_xdlc_control,
  const xdlc_cf_items *cf_items_nonext, const xdlc_cf_items *cf_items_ext,
  const value_string *u_modifier_short_vals_cmd,
  const value_string *u_modifier_short_vals_resp, gboolean is_response,
  gboolean is_extended, gboolean append_info);

#endif
