include/bcmtcp.h

/*
 * Fundamental constants relating to TCP Protocol
 *
 * Copyright (C) 2024, Broadcom.
 *
 *      Unless you and Broadcom execute a separate written software license
 * agreement governing use of this software, this software is licensed to you
 * under the terms of the GNU General Public License version 2 (the "GPL"),
 * available at http://www.broadcom.com/licenses/GPLv2.php, with the
 * following added to such license:
 *
 *      As a special exception, the copyright holders of this software give you
 * permission to link this software with independent modules, and to copy and
 * distribute the resulting executable under terms of your choice, provided that
 * you also meet, for each linked independent module, the terms and conditions of
 * the license of that module.  An independent module is a module which is not
 * derived from this software.  The special exception does not apply to any
 * modifications of the software.
 *
 *
 * <<Broadcom-WL-IPTag/Dual:>>
 */

#ifndef _bcmtcp_h_
#define _bcmtcp_h_

#ifndef _TYPEDEFS_H_
#include <typedefs.h>
#endif

/* This marks the start of a packed structure section. */
#include <packed_section_start.h>


#define TCP_SRC_PORT_OFFSET	0	/* TCP source port offset */
#define TCP_DEST_PORT_OFFSET	2	/* TCP dest port offset */
#define TCP_SEQ_NUM_OFFSET	4	/* TCP sequence number offset */
#define TCP_ACK_NUM_OFFSET	8	/* TCP acknowledgement number offset */
#define TCP_HLEN_OFFSET		12	/* HLEN and reserved bits offset */
#define TCP_FLAGS_OFFSET	13	/* FLAGS and reserved bits offset */
#define TCP_CHKSUM_OFFSET	16	/* TCP body checksum offset */

#define TCP_PORT_LEN		2	/* TCP port field length */

/* 8bit TCP flag field */
#define TCP_FLAG_URG            0x20
#define TCP_FLAG_ACK            0x10
#define TCP_FLAG_PSH            0x08
#define TCP_FLAG_RST            0x04
#define TCP_FLAG_SYN            0x02
#define TCP_FLAG_FIN            0x01

#define TCP_HLEN_MASK           0xf000
#define TCP_HLEN_SHIFT          12

/* These fields are stored in network order */
BWL_PRE_PACKED_STRUCT struct bcmtcp_hdr
{
	uint16	src_port;	/* Source Port Address */
	uint16	dst_port;	/* Destination Port Address */
	uint32	seq_num;	/* TCP Sequence Number */
	uint32	ack_num;	/* TCP Sequence Number */
	uint16	hdrlen_rsvd_flags;	/* Header length, reserved bits and flags */
	uint16	tcpwin;		/* TCP window */
	uint16	chksum;		/* Segment checksum with pseudoheader */
	uint16	urg_ptr;	/* Points to seq-num of byte following urg data */
} BWL_POST_PACKED_STRUCT;

#define TCP_MIN_HEADER_LEN 20

#define TCP_HDRLEN_MASK 0xf0
#define TCP_HDRLEN_SHIFT 4
#define TCP_HDRLEN(hdrlen) (((hdrlen) & TCP_HDRLEN_MASK) >> TCP_HDRLEN_SHIFT)

#define TCP_FLAGS_MASK  0x1f
#define TCP_FLAGS(hdrlen) ((hdrlen) & TCP_FLAGS_MASK)

/* This marks the end of a packed structure section. */
#include <packed_section_end.h>

/* To address round up by 32bit. */
#define IS_TCPSEQ_GE(a, b) ((a - b) < NBITVAL(31))		/* a >= b */
#define IS_TCPSEQ_LE(a, b) ((b - a) < NBITVAL(31))		/* a =< b */
#define IS_TCPSEQ_GT(a, b) !IS_TCPSEQ_LE(a, b)		/* a > b */
#define IS_TCPSEQ_LT(a, b) !IS_TCPSEQ_GE(a, b)		/* a < b */

#endif	/* #ifndef _bcmtcp_h_ */