hostchan.c

这个是LINUX下的GDB调度工具的源码

/* 
 * Copyright (C) 1995 Advanced RISC Machines Limited. All rights reserved.
 * 
 * This software may be freely used, copied, modified, and distributed
 * provided that the above copyright notice is preserved in all copies of the
 * software.
 */

/* -*-C-*-
 *
 * $Revision: 1.8 $
 *     $Date: 1999/11/01 15:32:59 $
 *
 *
 * hostchan.c - Semi Synchronous Host side channel interface for Angel.
 */

#include <stdio.h>

#ifdef HAVE_SYS_TIME_H
#  include <sys/time.h>
#else
#  include "winsock.h"
#  include "time.h"
#endif
#include "hsys.h"
#include "host.h"
#include "logging.h"
#include "chandefs.h"
#include "chanpriv.h"
#include "devclnt.h"
#include "buffers.h"
#include "drivers.h"
#include "adperr.h"
#include "devsw.h"
#include "hostchan.h"

#ifndef UNUSED
#define UNUSED(x) (x = x)  /* Silence compiler warnings for unused arguments */
#endif

#define HEARTRATE 5000000

/*
 * list of available drivers, declared in drivers.c
 */
extern DeviceDescr *devices[];

static DeviceDescr *deviceToUse = NULL;

static struct Channel {
    ChannelCallback callback;
    void *callback_state;
} channels[CI_NUM_CHANNELS];

static unsigned char HomeSeq;
static unsigned char OppoSeq;

/*
 * Handler for DC_APPL packets
 */
static DC_Appl_Handler dc_appl_handler = NULL;

/*
 * slots for registered asynchronous processing callback procedures
 */
#define MAX_ASYNC_CALLBACKS 8
static unsigned int             num_async_callbacks = 0;
static Adp_Async_Callback       async_callbacks[MAX_ASYNC_CALLBACKS];

/*
 * writeQueueRoot is the queue of write requests pending acknowledgement
 * writeQueueSend is the queue of pending write requests which will
 * be a subset of the list writeQueueRoot
 */
static Packet *writeQueueRoot = NULL;
static Packet *writeQueueSend = NULL;
static Packet *resend_pkt = NULL;
static int resending = FALSE;

/* heartbeat_enabled is a flag used to indicate whether the heartbeat is
 * currently turned on, heartbeat_enabled will be false in situations
 * where even though a heartbeat is being used it is problematical or
 * dis-advantageous to have it turned on, for instance during the 
 * initial stages of boot up
 */
unsigned int heartbeat_enabled = FALSE;
/* heartbeat_configured is set up by the device driver to indicate whether
 * the heartbeat is being used during this debug session.  In contrast to
 * heartbeat_enabled it must not be changed during a session.  The logic for
 * deciding whether to send a heartbeat is: Is heartbeat_configured for this
 * session? if and only if it is then if heartbeat[is currently]_enabled and
 * we are due to send a pulse then send it 
 */
unsigned int heartbeat_configured = TRUE;

void Adp_initSeq( void ) {
  Packet *tmp_pkt = writeQueueSend;

  HomeSeq = 0;
  OppoSeq = 0;
  if ( writeQueueSend != NULL) {
    while (writeQueueSend->pk_next !=NULL) {
      tmp_pkt = writeQueueSend;
      writeQueueSend = tmp_pkt->pk_next;
      DevSW_FreePacket(tmp_pkt);
    }
  }
  tmp_pkt = writeQueueRoot;
  if ( writeQueueRoot == NULL)
    return;

  while (writeQueueRoot->pk_next !=NULL) {
    tmp_pkt = writeQueueRoot;
    writeQueueRoot = tmp_pkt->pk_next;
    DevSW_FreePacket(tmp_pkt);
  }
  return;
}

/**********************************************************************/

/*
 *  Function: DummyCallback
 *   Purpose: Default callback routine to handle unexpected input
 *              on a channel
 *
 *    Params:
 *       Input: packet  The received packet
 *
 *              state   Contains nothing of significance
 *
 *   Returns: Nothing
 */
static void DummyCallback(Packet *packet, void *state)
{
    ChannelID chan;
    const char fmt[] = "Unexpected read on channel %u, length %d\n";
    char fmtbuf[sizeof(fmt) + 24];

    UNUSED(state);

    chan = *(packet->pk_buffer);
    sprintf(fmtbuf, fmt, chan, packet->pk_length);
    printf(fmtbuf);

    /*
     * junk this packet
     */
    DevSW_FreePacket(packet);
}

/*
 *  Function: BlockingCallback
 *   Purpose: Callback routine used to implement a blocking read call
 *
 *    Params:
 *       Input: packet  The received packet.
 *
 *      Output: state   Address of higher level's pointer to the received
 *                      packet.
 *
 *   Returns: Nothing
 */
static void BlockingCallback(Packet *packet, void *state)
{
    /*
     * Pass the packet back to the caller which requested a packet
     * from this channel.  This also flags the completion of the I/O
     * request to the blocking read call.
     */
    *((Packet **)state) = packet;
}

/*
 *  Function: FireCallback
 *   Purpose: Pass received packet along to the callback routine for
 *              the appropriate channel
 *
 *    Params:
 *       Input: packet  The received packet.
 *
 *   Returns: Nothing
 *
 * Post-conditions: The Target-to-Host sequence number for the channel
 *                      will have been incremented.
 */
static void FireCallback(Packet *packet)
{
    ChannelID chan;
    struct Channel *ch;

    /*
     * is this a sensible channel number?
     */
    chan = *(packet->pk_buffer);
    if (invalidChannelID(chan))
    {
        printf("ERROR: invalid ChannelID received from target\n");

        /*
         * free the packet's resources, 'cause no-one else will
         */
        DevSW_FreePacket(packet);
        return;
    }

    /*
     * looks OK - increment sequence number, and pass packet to callback
     */
    ch = channels + chan;
    (ch->callback)(packet, ch->callback_state);
}

/**********************************************************************/

/*
 * These are the externally visible functions.  They are documented
 * in hostchan.h
 */
void Adp_addToQueue(Packet **head, Packet *newpkt)
{
    /*
     * this is a bit of a hack
     */
    Packet *pk;

    /*
     * make sure that the hack we are about to use will work as expected
     */
    ASSERT(&(((Packet *)0)->pk_next) == 0, "bad struct Packet layout");

#if defined(DEBUG) && 0
    printf("Adp_addToQueue(%p, %p)\n", head, newpkt);
#endif

    /*
     * here's the hack - it relies upon the next
     * pointer being at the start of Packet.
     */
    pk = (Packet *)(head);

    /*
     * skip to the end of the queue
     */
    while (pk->pk_next != NULL)
        pk = pk->pk_next;

    /*
     * now add the new element
     */
    newpkt->pk_next = NULL;
    pk->pk_next = newpkt;
}

Packet *Adp_removeFromQueue(Packet **head)
{
    struct Packet *pk;

    pk = *head;

    if (pk != NULL)
        *head = pk->pk_next;

    return pk;
}

void Adp_SetLogEnable(int logEnableFlag)
{
  DevSW_SetLogEnable(logEnableFlag);
}

void Adp_SetLogfile(const char *filename)
{
  DevSW_SetLogfile(filename);
}

AdpErrs Adp_OpenDevice(const char *name, const char *arg,
                       unsigned int heartbeat_on)
{
    int i;
    AdpErrs retc;
    ChannelID chan;

#ifdef DEBUG
    printf("Adp_OpenDevice(%s, %s)\n", name, arg ? arg : "<NULL>");
#endif

    heartbeat_configured = heartbeat_on;
    if (deviceToUse != NULL)
        return adp_device_already_open;

    for (i = 0; (deviceToUse = devices[i]) != NULL; ++i)
        if (DevSW_Match(deviceToUse, name, arg) == adp_ok)
            break;

    if (deviceToUse == NULL)
        return adp_device_not_found;

    /*
     * we seem to have found a suitable device driver, so try to open it
     */
    if ((retc = DevSW_Open(deviceToUse, name, arg, DC_DBUG)) != adp_ok)
    {
        /* we don't have a device to use */
        deviceToUse = NULL;
        return retc;
    }

    /*
     * there is no explicit open on channels any more, so
     * initialise state for all channels.
     */
    for (chan = 0; chan < CI_NUM_CHANNELS; ++chan)
    {
        struct Channel *ch = channels + chan;

        ch->callback = DummyCallback;
        ch->callback_state = NULL;
        OppoSeq = 0;
        HomeSeq = 0;
    }

    return adp_ok;
}

AdpErrs Adp_CloseDevice(void)
{
    AdpErrs retc;

#ifdef DEBUG
    printf("Adp_CloseDevice\n");
#endif

    if (deviceToUse == NULL)
        return adp_device_not_open;

    heartbeat_enabled = FALSE;

    retc = DevSW_Close(deviceToUse, DC_DBUG);

    /*
     * we have to clear deviceToUse, even when the lower layers
     * faulted the close, otherwise the condition will never clear
     */
    if (retc != adp_ok)
        WARN("DevSW_Close faulted the call");

    deviceToUse = NULL;
    return retc;
}

AdpErrs Adp_Ioctl(int opcode, void *args)
{
#ifdef DEBUG
    printf("Adp_Ioctl\n");
#endif

    if (deviceToUse == NULL)
        return adp_device_not_open;

    return DevSW_Ioctl(deviceToUse, opcode, args);
}

AdpErrs Adp_ChannelRegisterRead(const ChannelID chan,
                                const ChannelCallback cbfunc,
                                void *cbstate)
{
#ifdef DEBUG
    printf("Adp_ChannelRegisterRead(%d, %p, %x)\n", chan, cbfunc, cbstate);
#endif

    if (deviceToUse == NULL)
        return adp_device_not_open;

    if (invalidChannelID(chan))
        return adp_bad_channel_id;

    if (cbfunc == NULL)
    {
        channels[chan].callback = DummyCallback;
        channels[chan].callback_state = NULL;
    }
    else
    {
        channels[chan].callback = cbfunc;
        channels[chan].callback_state = cbstate;
    }

    return adp_ok;
}

AdpErrs Adp_ChannelRead(const ChannelID chan, Packet **packet)
{
    struct Channel *ch;

#ifdef DEBUG
    printf("Adp_ChannelRead(%d, %x)\n", chan, *packet);
#endif

    if (deviceToUse == NULL)
        return adp_device_not_open;

    if (invalidChannelID(chan))
        return adp_bad_channel_id;

    /*
     * if a callback has already been registered for this
     * channel, then we do not allow this blocking read.
     */
    ch = channels + chan;
    if (ch->callback != DummyCallback)
        return adp_callback_already_registered;

    /*
     * OK, use our own callback to wait for a packet to arrive
     * on this channel
     */
    ch->callback = BlockingCallback;
    ch->callback_state = packet;
    *packet = NULL;

    /*
     * keep polling until a packet appears for this channel
     */
    while (((volatile Packet *)(*packet)) == NULL)
        /*
         * this call will block until a packet is read on any channel
         */
        Adp_AsynchronousProcessing(async_block_on_read);

    /*
     * OK, the packet has arrived: clear the callback
     */
    ch->callback = DummyCallback;
    ch->callback_state = NULL;

    return adp_ok;
}

static AdpErrs ChannelWrite(
    const ChannelID chan, Packet *packet, AsyncMode mode)
{
    struct Channel *ch;
    unsigned char *cptr;

#ifdef DEBUG
    printf( "Adp_ChannelWrite(%d, %x)\n", chan, packet );
#endif

    if (deviceToUse == NULL)
        return adp_device_not_open;

    if (invalidChannelID(chan))
        return adp_bad_channel_id;

    /*
     * fill in the channels header at the start of this buffer
     */
    ch = channels + chan;
    cptr = packet->pk_buffer;
    *cptr++ = chan;
    *cptr = 0;
    packet->pk_length += CHAN_HEADER_SIZE;

    /*
     * OK, add this packet to the write queue, and try to flush it out
     */

    Adp_addToQueue(&writeQueueSend, packet);
    Adp_AsynchronousProcessing(mode);

    return adp_ok;
}

AdpErrs Adp_ChannelWrite(const ChannelID chan, Packet *packet) {
  return ChannelWrite(chan, packet, async_block_on_write);
}

AdpErrs Adp_ChannelWriteAsync(const ChannelID chan, Packet *packet) {
  return ChannelWrite(chan, packet, async_block_on_nothing);
}

static AdpErrs send_resend_msg(DeviceID devid) {

  /*
   * Send a resend message, usually in response to a bad packet or
   * a resend request */
  Packet * packet;
  packet = DevSW_AllocatePacket(CF_DATA_BYTE_POS);
  packet->pk_buffer[CF_CHANNEL_BYTE_POS] = CI_PRIVATE;
  packet->pk_buffer[CF_HOME_SEQ_BYTE_POS] = HomeSeq;
  packet->pk_buffer[CF_OPPO_SEQ_BYTE_POS] = OppoSeq;
  packet->pk_buffer[CF_FLAGS_BYTE_POS] = CF_RELIABLE | CF_RESEND;
  packet->pk_length = CF_DATA_BYTE_POS;
  return DevSW_Write(deviceToUse, packet, devid);
}

static AdpErrs check_seq(unsigned char msg_home, unsigned char msg_oppo) {
  Packet *tmp_pkt;

  UNUSED(msg_oppo);
  /* 
   * check if we have got an ack for anything and if so remove it from the
   * queue
   */
  if (msg_home == (unsigned char)(OppoSeq+1)) {
    /*
     * arrived in sequence can increment our opposing seq number and remove
     * the relevant packet from our queue
     * check that the packet we're going to remove really is the right one
     */
    tmp_pkt = writeQueueRoot;
    while ((tmp_pkt->pk_next != NULL) &&
           (tmp_pkt->pk_next->pk_buffer[CF_HOME_SEQ_BYTE_POS]
            != OppoSeq)){
      tmp_pkt = tmp_pkt->pk_next;
    }
    OppoSeq++;
    if (tmp_pkt->pk_next == NULL) {
#ifdef DEBUG
      printf("trying to remove a non existant packet\n");
#endif
      return adp_bad_packet;
    }
    else {
      Packet *tmp = tmp_pkt->pk_next;
#ifdef RET_DEBUG
      printf("removing a packet from the root queue\n");
#endif
      tmp_pkt->pk_next = tmp_pkt->pk_next->pk_next;
      /* remove the appropriate packet */
      DevSW_FreePacket(tmp);
    return adp_ok;