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/*

 *      LAPB release 002

 *

 *      This code REQUIRES 2.1.15 or higher/ NET3.038

 *

 *      This module:

 *              This module 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.

 *

 *      History

 *      LAPB 001        Jonathan Naylor Started Coding

 *      LAPB 002        Jonathan Naylor New timer architecture.

 */

#include <linux/errno.h>

#include <linux/types.h>

#include <linux/socket.h>

#include <linux/in.h>

#include <linux/kernel.h>

#include <linux/sched.h>

#include <linux/timer.h>

#include <linux/string.h>

#include <linux/sockios.h>

#include <linux/net.h>

#include <linux/inet.h>

#include <linux/skbuff.h>

#include <net/sock.h>

#include <asm/uaccess.h>

#include <asm/system.h>

#include <linux/fcntl.h>

#include <linux/mm.h>

#include <linux/interrupt.h>

#include <net/lapb.h>

/*

 *  This procedure is passed a buffer descriptor for an iframe. It builds

 *  the rest of the control part of the frame and then writes it out.

 */

static void lapb_send_iframe(lapb_cb *lapb, struct sk_buff *skb, int poll_bit)

{

        unsigned char *frame;

        if (skb == NULL)

                return;

        if (lapb->mode & LAPB_EXTENDED) {

                frame = skb_push(skb, 2);

                frame[0] = LAPB_I;

                frame[0] |= (lapb->vs << 1);

                frame[1] = (poll_bit) ? LAPB_EPF : 0;

                frame[1] |= (lapb->vr << 1);

        } else {

                frame = skb_push(skb, 1);

                *frame = LAPB_I;

                *frame |= (poll_bit) ? LAPB_SPF : 0;

                *frame |= (lapb->vr << 5);

                *frame |= (lapb->vs << 1);

        }

#if LAPB_DEBUG > 1

        printk(KERN_DEBUG "lapb: (%p) S%d TX I(%d) S%d R%d\n", lapb->token, lapb->state, poll_bit, lapb->vs, lapb->vr);

#endif

        lapb_transmit_buffer(lapb, skb, LAPB_COMMAND);

}

void lapb_kick(lapb_cb *lapb)

{

        struct sk_buff *skb, *skbn;

        unsigned short modulus, start, end;

        modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS;

        start = (skb_peek(&lapb->ack_queue) == NULL) ? lapb->va : lapb->vs;

        end   = (lapb->va + lapb->window) % modulus;

        if (!(lapb->condition & LAPB_PEER_RX_BUSY_CONDITION) &&

            start != end                                &&

            skb_peek(&lapb->write_queue) != NULL) {

                lapb->vs = start;

                /*

                 * Dequeue the frame and copy it.

                 */

                skb  = skb_dequeue(&lapb->write_queue);

                do {

                        if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {

                                skb_queue_head(&lapb->write_queue, skb);

                                break;

                        }

                        if (skb->sk != NULL)

                                skb_set_owner_w(skbn, skb->sk);

                        /*

                         * Transmit the frame copy.

                         */

                        lapb_send_iframe(lapb, skbn, LAPB_POLLOFF);

                        lapb->vs = (lapb->vs + 1) % modulus;

                        /*

                         * Requeue the original data frame.

                         */

                        skb_queue_tail(&lapb->ack_queue, skb);

                } while (lapb->vs != end && (skb = skb_dequeue(&lapb->write_queue)) != NULL);

                lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;

                if (!lapb_t1timer_running(lapb))

                        lapb_start_t1timer(lapb);

        }

}

void lapb_transmit_buffer(lapb_cb *lapb, struct sk_buff *skb, int type)

{

        unsigned char *ptr;

        ptr = skb_push(skb, 1);

        if (lapb->mode & LAPB_MLP) {

                if (lapb->mode & LAPB_DCE) {

                        if (type == LAPB_COMMAND)

                                *ptr = LAPB_ADDR_C;

                        if (type == LAPB_RESPONSE)

                                *ptr = LAPB_ADDR_D;

                } else {

                        if (type == LAPB_COMMAND)

                                *ptr = LAPB_ADDR_D;

                        if (type == LAPB_RESPONSE)

                                *ptr = LAPB_ADDR_C;

                }

        } else {

                if (lapb->mode & LAPB_DCE) {

                        if (type == LAPB_COMMAND)

                                *ptr = LAPB_ADDR_A;

                        if (type == LAPB_RESPONSE)

                                *ptr = LAPB_ADDR_B;

                } else {

                        if (type == LAPB_COMMAND)

                                *ptr = LAPB_ADDR_B;

                        if (type == LAPB_RESPONSE)

                                *ptr = LAPB_ADDR_A;

                }

        }

#if LAPB_DEBUG > 2

        printk(KERN_DEBUG "lapb: (%p) S%d TX %02X %02X %02X\n", lapb->token, lapb->state, skb->data[0], skb->data[1], skb->data[2]);

#endif

        if (!lapb_data_transmit(lapb, skb))

                kfree_skb(skb);

}

void lapb_establish_data_link(lapb_cb *lapb)

{

        lapb->condition = 0x00;

        lapb->n2count   = 0;

        if (lapb->mode & LAPB_EXTENDED) {

#if LAPB_DEBUG > 1

                printk(KERN_DEBUG "lapb: (%p) S%d TX SABME(1)\n", lapb->token, lapb->state);

#endif

                lapb_send_control(lapb, LAPB_SABME, LAPB_POLLON, LAPB_COMMAND);

        } else {

#if LAPB_DEBUG > 1

                printk(KERN_DEBUG "lapb: (%p) S%d TX SABM(1)\n", lapb->token, lapb->state);

#endif

                lapb_send_control(lapb, LAPB_SABM, LAPB_POLLON, LAPB_COMMAND);

        }

        lapb_start_t1timer(lapb);

        lapb_stop_t2timer(lapb);

}

void lapb_enquiry_response(lapb_cb *lapb)

{

#if LAPB_DEBUG > 1

        printk(KERN_DEBUG "lapb: (%p) S%d TX RR(1) R%d\n", lapb->token, lapb->state, lapb->vr);

#endif

        lapb_send_control(lapb, LAPB_RR, LAPB_POLLON, LAPB_RESPONSE);

        lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;

}

void lapb_timeout_response(lapb_cb *lapb)

{

#if LAPB_DEBUG > 1

        printk(KERN_DEBUG "lapb: (%p) S%d TX RR(0) R%d\n", lapb->token, lapb->state, lapb->vr);

#endif

        lapb_send_control(lapb, LAPB_RR, LAPB_POLLOFF, LAPB_RESPONSE);

        lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;

}

void lapb_check_iframes_acked(lapb_cb *lapb, unsigned short nr)

{

        if (lapb->vs == nr) {

                lapb_frames_acked(lapb, nr);

                lapb_stop_t1timer(lapb);

                lapb->n2count = 0;

        } else {

                if (lapb->va != nr) {

                        lapb_frames_acked(lapb, nr);

                        lapb_start_t1timer(lapb);

                }

        }

}

void lapb_check_need_response(lapb_cb *lapb, int type, int pf)

{

        if (type == LAPB_COMMAND && pf)

                lapb_enquiry_response(lapb);

}