/*--------------------------------------------------------------------------
**
**  Copyright (c) 2003, Tom Hunter (see license.txt)
**
**  Name: channel.c
**
**  Description:
**      Perform simulation of CDC 6600 channels.
**
**--------------------------------------------------------------------------
*/

/*
**  -------------
**  Include Files
**  -------------
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "const.h"
#include "types.h"
#include "proto.h"

/*
**  -----------------
**  Private Constants
**  -----------------
*/

/*
**  -----------------------
**  Private Macro Functions
**  -----------------------
*/

/*
**  -----------------------------------------
**  Private Typedef and Structure Definitions
**  -----------------------------------------
*/

/*
**  ---------------------------
**  Private Function Prototypes
**  ---------------------------
*/

/*
**  ----------------
**  Public Variables
**  ----------------
*/
ChSlot *channel;
ChSlot *activeChannel;
DevSlot *activeDevice;
u8 channelCount;

/*
**  -----------------
**  Private Variables
**  -----------------
*/
static u8 ch = 0;

/*
**--------------------------------------------------------------------------
**
**  Public Functions
**
**--------------------------------------------------------------------------
*/


/*--------------------------------------------------------------------------
**  Purpose:        Initialise channels.
**
**  Parameters:     Name        Description.
**                  count       channel count
**
**  Returns:        Nothing.
**
**------------------------------------------------------------------------*/
void channelInit(u8 count)
    {
    /*
    **  Allocate channel structures.
    */
    channelCount = count;
    channel = calloc(count, sizeof(ChSlot));
    if (channel == NULL)
        {
        fprintf(stderr, "Failed to allocate channel control blocks\n");
        exit(1);
        }

    /*
    **  Initialise all channels.
    */
    for (ch = 0; ch < channelCount; ch++)
        {
        channel[ch].id = ch;
        }

    /*
    **  Print a friendly message.
    */
    printf("Channels initialised (number of channels %o)\n", channelCount);
    }

/*--------------------------------------------------------------------------
**  Purpose:        Return device control block attached to a channel.
**
**  Parameters:     Name        Description.
**                  channelNo   channel number to attach to.
**                  devType     device type
**
**  Returns:        Pointer to device slot.
**
**------------------------------------------------------------------------*/
DevSlot *channelFindDevice(u8 channelNo, u8 devType)
    {
    DevSlot *device;
    ChSlot *cp;

    cp = channel + channelNo;
    device = cp->firstDevice;

    /*
    **  Try to locate device control block.
    */
    while (device != NULL) 
        {
        if (device->devType == devType)
            {
            return(device);
            }

        device = device->next;
        }

    return(NULL);
    }

/*--------------------------------------------------------------------------
**  Purpose:        Attach device to channel.
**
**  Parameters:     Name        Description.
**                  channelNo   channel number to attach to.
**                  devType     device type
**
**  Returns:        Pointer to device slot.
**
**------------------------------------------------------------------------*/
DevSlot *channelAttach(u8 channelNo, u8 devType)
    {
    DevSlot *device;

    activeChannel = channel + channelNo;
    device = activeChannel->firstDevice;

    /*
    **  Try to locate existing device control block.
    */
    while (device != NULL) 
        {
        if (device->devType == devType)
            {
            return(device);
            }

        device = device->next;
        }

    /*
    **  No device control block of this type found, allocate new one.
    */
    device = calloc(1, sizeof(DevSlot));
    if (device == NULL)
        {
        fprintf(stderr, "Failed to allocate control block for Channel %d\n",channelNo);
        exit(1);
        }

    /*
    **  Link device control block into the chain of devices hanging of this channel.
    */
    device->next = activeChannel->firstDevice;
    activeChannel->firstDevice = device;
    device->channel = activeChannel;
    device->devType = devType;

    return(device);
    }

/*--------------------------------------------------------------------------
**  Purpose:        Issue a function code to all attached devices.
**
**  Parameters:     Name        Description.
**                  funcCode    function code
**
**  Returns:        Nothing.
**
**------------------------------------------------------------------------*/
void channelFunction(PpWord funcCode)
    {
    FcStatus status = FcDeclined;

#if 0
    if (activeChannel->id == 010 && funcCode == 0)
        {
        activeChannel->ioDevice = NULL;
        activeChannel->full = TRUE;
        activeChannel->active = TRUE;
        return;
        }
#endif

    for (activeDevice = activeChannel->firstDevice; activeDevice != NULL; activeDevice = activeDevice->next)
        {
        status = activeDevice->func(funcCode);
        if (status == FcAccepted)
            {
            /*
            **  Device has claimed function code - select it for I/O.
            */
            activeChannel->ioDevice = activeDevice;
            break;
            }

        if (status == FcProcessed)
            {
            /*
            **  Device has processed function code - no need for I/O.
            */
            break;
            }
        }

    if (activeDevice == NULL || status == FcDeclined)
        {
        /*
        **  No device has claimed the function code - keep channel active
        **  and full, but disconnect device.
        */
//        traceChannelFunction(funcCode);
        activeChannel->ioDevice = NULL;
        activeChannel->full = TRUE;
        activeChannel->active = TRUE;
        }
    }

/*--------------------------------------------------------------------------
**  Purpose:        Activate a channel and let attached device know.
**
**  Parameters:     Name        Description.
**                  channelNo   channel number activated
**
**  Returns:        Nothing.
**
**------------------------------------------------------------------------*/
void channelActivate(void)
    {
    activeChannel->active = TRUE;

    if (activeChannel->ioDevice != NULL)
        {
        activeDevice = activeChannel->ioDevice;
        activeDevice->activate();
        }
    }

/*--------------------------------------------------------------------------
**  Purpose:        Disconnect a channel and let active device know.
**
**  Parameters:     Name        Description.
**
**  Returns:        Nothing.
**
**------------------------------------------------------------------------*/
void channelDisconnect(void)
    {
    activeChannel->active = FALSE;
    activeChannel->full = FALSE;

    if (activeChannel->ioDevice != NULL)
        {
        activeDevice = activeChannel->ioDevice;
        activeDevice->disconnect();
        }
    }

/*--------------------------------------------------------------------------
**  Purpose:        IO on a channel.
**
**  Parameters:     Name        Description.
**
**  Returns:        Nothing
**
**------------------------------------------------------------------------*/
void channelIo(void)
    {
    /*
    **  Perform request.
    */
    if (   (activeChannel->active || activeChannel->id == 014)
        && activeChannel->ioDevice != NULL)
        {
        activeDevice = activeChannel->ioDevice;
        activeDevice->io();
        }
    }

/*---------------------------  End Of File  ------------------------------*/