tsksio.cpp

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/*
   CPPTask - A Multitasking Kernel For C++

   Version 1.0 08-12-91

   Ported by Rich Smith from:

   Public Domain Software written by
      Thomas Wagner
      Patschkauer Weg 31
      D-1000 Berlin 33
      West Germany

   TSKSIO.CPP - Serial I/O interface routines.

   Subroutines:
      sioint3
      sioint4
      commport::chng_rts
      commport::transmit_ready
      commport::modem_status_int
      commport::receive_ready
      commport::sioint
      commport::commport
      commport::~commport
      commport::change_rts
      commport::change_dtr
      commport::change_baud
      commport::change_parity
      commport::change_wordlength
      commport::change_stopbits
      commport::watch_modem
      commport::protocol
      commport::send
      commport::receive
      commport::rcv_overrun
      commport::check
      commport::modem_status
      commport::complete
      commport::wait_complete
      commport::flush_receive

   The tables used are:

      port_list   The pointer to the list of defined ports. Newly
                  defined ports are added to the end of the list.
                  Ports can never be deleted. Each port descriptor
                  contains the hardware info for the port, plus a
                  pointer to the associated sio-control-block if the
                  port was initialized.
                  
      port_last   The pointer to the last element in port_list.

      irq_array   Is an array of pointers to sio-control-blocks. For
                  each possible IRQ-line the entry in this table points
                  to the first block active for this line. If the IRQ
                  is shared, sio-blocks are chained into this list via 
                  their "next" pointer.

      irq_procs   Contains the pointer to the interrupt handler function
                  for the corresponding IRQ-line.

      port_descr  Contains the statically defined port descriptor blocks.

   NOTE:    You can not dynamically define ports for IRQ-lines that
            have no interrupt handler function defined. To be completely
            flexible, you would have to define sioint-handlers for all
            possible IRQs and enter the addresses into the irq_procs array.

   CAUTION: Please restrict the installation and removal of comm-
            ports to *one* task. The manipulation of the lists is
            not protected, so simultaneous install/remove calls
            may cause trouble. Since ports are normally installed and
            removed in the main task, the protection of critical regions
            seemed unnecessary.

   CAUTION: Shared interrupt logic and IRQ-lines above 4 were not
            tested due to the lack of suitable hardware. Changes may
            be necessary in the handling of the modem control register
            OUT2 line that normally controls interrupt enable, depending
            on the multiport-hardware installed in the target system.

*/

#include "task.hpp"
#include "sio.hpp"

#define MAX_IRQ   16    /* Maximum number of interrupt lines, 
                           16 for AT, 8 for XT. Can be left at 16 */

#define CHAIN_IRQBIT    0x04  /* Chained int controller IRQ bit */

#define RESTORE_DEFAULT 1     /* Restore parameter for remove_all */

#define RTS       0x02
#define DTR       0x01
#define OUT2      0x08

#define ERR_MASK  0x1e

#define inta00    0x20   /* 8259 interrupt controller control-port */
#define inta01    0x21   /* 8259 interrupt controller mask-port */

#define inta10    0xa0   /* secondary 8259 control-port for IRQ 8-15 */
#define inta11    0xa1   /* secondary 8259 mask-port for IRQ 8-15 */

#define rdserv    0x0b   /* read service register control value */
#define eoi       0x20   /* end of interrupt signal for 8259 */

#define intdata   0x0b   /* Enable Interrupts except Line status */

#define rxreadybit 0x01
#define txemptybit 0x40
#define txreadybit 0x20
#define framingbit 0x08
#define breakbit   0x10

/* Note: In version 1.1, port offsets start at 0, not 8 */

#define linecontrol  0x03
#define linestatus   0x05
#define intid        0x02
#define intenable    0x01
#define modemcontrol 0x04
#define modemstatus  0x06
#define receivedata  0x00
#define transmitdata 0x00

#define baudreg_dll  0x00     /* baud rate least significant byte */
#define baudreg_dlm  0x01     /* baud rate most significant byte */

/*
   Default values for initialising the ports.
   Change to your liking (but remember that OUT2 must be set in the
   modem control register to allow interrupts to come through with 
   normal controllers).
*/

#define dflt_modcon 0x0b   /* Modem Control: Activate DTR, RTS, OUT2 */
#define dflt_baud   96     /* Baud Rate Divisor: 1200 Baud */
#define dflt_lcon   0x03   /* Line Control: No Parity, 1 Stop, 8 Data */

/*
   Defined baud rates. You may expand this table with non-standard
   rates if desired.
*/

local long baud_table [] = {
                               50L, 2304L,
                               75L, 1536L,
                              110L, 1047L,
                              134L,  857L,
                              150L,  768L,
                              300L,  384L,
                              600L,  192L,
                             1200L,   96L,
                             1800L,   64L,
                             2000L,   58L,
                             2400L,   48L,
                             3600L,   32L,
                             4800L,   24L,
                             7200L,   16L,
                             9600L,   12L,
                            19200L,    6L,
                            38400L,    3L,
                                0L,    0L };

local byte force_transmit_ready;       /* flag to indicate
                                          transmitter needs service */

/*-------------------------------------------------------------------------*/

/*
   To add static support for other COM-Ports, define
      - Port base
      - IRQ-Line
      - Interrupt vector
   here, and add the necessary data to the port_descr array.
   If the port does *not* share an IRQ with the predefined ports,
   define the corresponding interrupt function by duplicating siointx,
   and place the entry for this function into the irq_procs array.

*/

#define STATIC_PORTS  2       /* Number of statically defined ports */

/* Note: In version 1.1, port offsets start at 0, not 8 */

#define com1_base    0x3f8    /* COM1 port base */
#define com2_base    0x2f8    /* COM2 port base */

#define com1_irq     4        /* IRQ-Line for COM1 */
#define com2_irq     3        /* IRQ-Line for COM2 */

#define com1_vect    0x0c     /* Interrupt vector for COM1 */
#define com2_vect    0x0b     /* Interrupt vector for COM2 */

/*-------------------------------------------------------------------------*/


typedef void (interrupt far * intprocptr)(void);

void interrupt far sioint3 (void);
void interrupt far sioint4 (void);

/* 
   Table of Interrupt handler functions for each IRQ line.
*/

local intprocptr irq_procs [MAX_IRQ] = {  NULL,    /* IRQ 0 */
                                          NULL,    /* IRQ 1 */
                                          NULL,    /* IRQ 2 */
                                          (intprocptr)sioint3, /* IRQ 3 */
                                          (intprocptr)sioint4, /* IRQ 4 */
                                          NULL,    /* IRQ 5 */
                                          NULL,    /* IRQ 6 */
                                          NULL,    /* IRQ 7 */
                                          NULL,    /* IRQ 8 */
                                          NULL,    /* IRQ 9 */
                                          NULL,    /* IRQ 10 */
                                          NULL,    /* IRQ 11 */
                                          NULL,    /* IRQ 12 */
                                          NULL,    /* IRQ 13 */
                                          NULL,    /* IRQ 14 */
                                          NULL };  /* IRQ 15 */


/* When adding entries to port_descr, be sure to chain the 
   elements in ascending order via the first field, and to
   increase the internal port number in the second field. */

local port_data port_descr [STATIC_PORTS] = {
     { &port_descr[1], 0, NULL, com1_base, com1_irq, com1_vect },
     { NULL,           1, NULL, com2_base, com2_irq, com2_vect }
};

local commptr irq_array [MAX_IRQ] = { NULL };

local portptr port_list = &port_descr [0];
local portptr port_last = &port_descr [1];

local int ports = STATIC_PORTS;

extern funcptr v24_remove_func;

/*-------------------------------------------------------------------------*/


void commport::chng_rts (int on)
{
   rtsoff = (byte)(!on);
   cmodcontrol = (cmodcontrol & ~RTS) | ((on) ? RTS : 0);
   tsk_outp (port_base + modemcontrol, cmodcontrol);
}


void commport::transmit_ready (void)
{
   int i;

   force_transmit_ready = 0;

   if ((i = r_xoff) < 0)
      {
      tsk_outp (port_base + transmitdata, (i == -1) ? XOFF : XON);
      r_xoff = (i == -1) ? 1 : 0;
      xmit_pending = 1;
      return;
      }

   xmit_pending = 0;

   if (!(wait_xmit = (byte)(xmit_pipe.check_pipe () != -1)))
      return;

   if ((modem_flags & modstat) ^ modem_flags)
      return;

   if (flags & XONXOFF && t_xoff)
      return;

   wait_xmit = 0;

   if ((i = xmit_pipe.c_read_pipe ()) < 0)
      return;

   tsk_outp (port_base + transmitdata, (byte)i);
   xmit_pending = 1;
}


void commport::modem_status_int (void)
{
   modstat = tsk_inp (port_base + modemstatus);

   if (wait_xmit)
      transmit_ready ();
}


void commport::receive_ready (void)
{
   word status;
   word ch;

   while ((status = tsk_inp (port_base + linestatus)) & rxreadybit)
      {
      /* Correct for possible loss of transmit interrupt from IIR register */   
      if (status & txreadybit)
          force_transmit_ready = 1;

      tsk_nop ();
      ch = tsk_inp (port_base + receivedata);

      if (flags & XONXOFF)
         {
         if (ch == XON)
            {
            t_xoff = 0;
            if (wait_xmit)
               transmit_ready ();
            continue;
            }
         else if (ch == XOFF)
            {
            t_xoff = 1;
            continue;
            }
         if (!r_xoff &&
             rcv_pipe.wpipe_free () < xoff_threshold)
            {
            r_xoff = -1;
            if (!xmit_pending)
               transmit_ready ();
            }
         }

      if (flags & RTSCTS && !rtsoff)
         if (rcv_pipe.wpipe_free () < xoff_threshold)
            chng_rts (0);

      status = (status & ERR_MASK) << 8;
      if (rcv_pipe.c_write_wpipe (ch | status) < 0)
         overrun = 1;
      }
}


/*-------------------------------------------------------------------------*/


void commport::sioint (void)
{
   int id;

   force_transmit_ready = 0;

   while (!((id = tsk_inp (port_base + intid)) & 1))
      switch (id & 0x07)
         {
         case 0x00:  modem_status_int ();
                     break;

         case 0x02:  transmit_ready ();
                     break;

         case 0x04:  receive_ready ();
                     break;

/*       case 0x06:  line_status_int (); (currently not used)
                     break;
*/
         }
      if (force_transmit_ready)
         transmit_ready ();
}


void interrupt far sioint3 (void)
{
   commptr curr;

   tsk_sti ();
   for (curr = irq_array [3]; curr != NULL; curr = curr->next)
      curr->sioint ();

   tsk_cli ();
   /* NOTE: for IRQ's 8-15, add the following here:
      tsk_outp (inta10, eoi);
   */
   tsk_outp (inta00, eoi);
}


void interrupt far sioint4 (void)
{
   commptr curr;

   tsk_sti ();
   for (curr = irq_array [4]; curr != NULL; curr = curr->next)
      curr->sioint ();

   tsk_cli ();
   /* NOTE: for IRQ's 8-15, add the following here:
      tsk_outp (inta10, eoi);
   */
   tsk_outp (inta00, eoi);
}

/*-------------------------------------------------------------------------*/

commport::commport (int portnum, int init,
                          farptr rcvbuf, word rcvsize,
                          farptr xmitbuf, word xmitsize)
:xmit_pipe(xmitbuf, xmitsize), rcv_pipe(rcvbuf, rcvsize)
{
   portptr portp;
   int pbase;
   intprocptr far *intptr;
   int i, inta;

   if (port < 0 || !rcvsize || !xmitsize)
      return;

   portp = port_list;

   if (portnum & 0x80)     /* Relative port number */
      {
      portnum &= 0x7f;
      if (portnum > 4)
         return;
      pbase = *((wordptr)(MK_FP (0x40, portnum * 2)));
      if (!pbase)
         return;

      for (portnum = 0; portnum < ports; portnum++, portp = portp->next)
         if (portp->base == pbase)
            break;

      if (portnum >= ports)
         return;