#include "ttem_endian_port.h"

struct  termio  termio_struct1, termio_struct2;
int     	ch_status_flag1, ch_status_flag2;
int     	shmid, target_pid;
char    	*shm_addr;
CSR_TYPE 	*csr;

void    sigfun(int sig)
{
  int   i,j,k;

  shmctl(shmid, IPC_RMID, 0);
  ioctl(DEVCONIN, TCSETA, &termio_struct1);
  fcntl(DEVCONIN, F_SETFL, ch_status_flag1);
  printf("\n\nTTY EMULATOR DRIVER GOING DOWN ON SIGNAL %d \n\n", sig);
  kill(target_pid, SIGTERM);
  exit(sig);
}

int     main(int argc, char *argv[])
{
  struct 	sigaction new;
  sigset_t   	mask_sigs;
  int   	i,j,k, nsigs;
  int   	buf_used, high_watermark, low_watermark;
  int   	in,out,xmtr_off;
  char  	inbuf[INBUFSIZE],inchar;
  int sigs[] = 	{SIGHUP,SIGINT,SIGQUIT,
                 SIGSEGV, SIGBUS, SIGTERM, SIGXFSZ};

  nsigs = sizeof(sigs)/sizeof(int);
  target_pid = atoi(argv[1]);
  in=out=0;
  buf_used=0;
  xmtr_off = 1;
  /*  high_watermark = HIGHWTRMRK;  */
  /*  low_watermark  = LOWWTRMRK;   */
  printf("\n terminal emulator starting\n");
  sigemptyset(&mask_sigs);
  for(i=0; i< nsigs; i++)
       sigaddset(&mask_sigs, sigs[i]);
  for(i=0; i< nsigs; i++){
      new.sa_handler = sigfun;
      new.sa_mask = mask_sigs;
      new.sa_flags = SA_RESTART;
      if(sigaction(sigs[i], &new, NULL) == -1){
         perror("can't set signals: ");
         exit(1);
      }
  }
  ioctl(DEVCONIN, TCGETA, &termio_struct1);
  termio_struct2 = termio_struct1;

  ch_status_flag1 = fcntl(DEVCONIN, F_GETFL, 0);
  ch_status_flag2 = ch_status_flag1;

  termio_struct2.c_lflag &= ~(ISIG | ICANON | ECHO | ECHOK);
  termio_struct2.c_iflag &= ~(ICRNL | ISTRIP);
  // termio_struct2.c_oflag &= ~OPOST;
  termio_struct2.c_cc[4]  = 1;
  termio_struct2.c_cc[5]  = 1;

  if(ioctl(DEVCONIN, TCSETA, &termio_struct2) == -1){
        perror("ioctl tcset1 error");
        exit(1);
  }

  ch_status_flag2 |= O_NONBLOCK;

  if(fcntl(DEVCONIN, F_SETFL, ch_status_flag2) == -1){
        perror("fcntl f_setfl1 error");
        exit(1);
  }

  if((shmid = shmget(SHKEY, 4096, 0)) == -1){
        perror("shmget error");
        sigfun( -1 );
  }

  if((shm_addr = shmat(shmid, 0, 0)) == (char *)-1){
        perror("shmat error");
        sigfun( -1 );
  }

  csr = (CSR_TYPE *)shm_addr;

  while(1){
        if(buf_used < (INBUFSIZE - 1)){
           switch(read(DEVCONIN, &inchar, 1)){
                case -1: if(errno == EWOULDBLOCK |
                            errno == EAGAIN){
                           break;
                         }else{
                           perror("read error");
                           sigfun( -1 );
                         }
                case 0:  perror("read at EOF");
                         sigfun( -1 );
                case 1:  if(buf_used < (INBUFSIZE - 1)){
                              inbuf[in] = inchar;
                              in = (in + 1)%INBUFSIZE;
                              ++buf_used;
			 }
			 if(inchar == '\r' && buf_used < (INBUFSIZE - 1)){
                              inbuf[in] = '\n';
                              in = (in + 1)%INBUFSIZE;
                              ++buf_used;
                         }
                         break;
                default: perror("unknown read return");
                         sigfun( -1 );
           }
        }
        if(buf_used != 0 && csr->rcsr.rcsr_bit.done == 0){
           csr->rbuf.RBUF = inbuf[out];
           out = (out + 1)%INBUFSIZE;
           --buf_used;
           csr->rcsr.rcsr_bit.done = 1;
	   // if interrupts are enabled send an interrupt
	   if(csr->rcsr.rcsr_bit.int_enbl == 1){
             if(kill(target_pid,SIGUSR1) == -1){
                perror("signal recv error");
                sigfun( -1 );
             }
	   }
        }
 
 
	// if transmitter is asking to wake up
        if(xmtr_off && csr->xcsr.xcsr_bit.int_enbl == 1 &&
                    csr->xcsr.xcsr_bit.done == 0){
	   // wake up quiesced transmitter
           if(kill(target_pid,SIGUSR2) == -1){
                perror("signal xmit error");
                sigfun( -1 );
           }
	   xmtr_off = 0;
        }

	// if transmitter has a character for the screen
        if(csr->xcsr.xcsr_bit.done == 1){
	   if(write(DEVCONOUT, &(csr->xbuf.XBUF), 1)
                                                    == -1){
                perror("write to console error");
                sigfun( -1 );
           }
           csr->xcsr.xcsr_bit.done = 0;
	   if(csr->xbuf.xbuf_bit.byte == 'Q')sigfun( -1 );
	   if(csr->xcsr.xcsr_bit.int_enbl == 1){
	   // if interrupts are enabled send an interrupt
             if(kill(target_pid,SIGUSR2) == -1){
                perror("signal xmit error");
                sigfun( -1 );
             }
	   }
        }

	if(csr->xcsr.xcsr_bit.int_enbl == 0)xmtr_off = 1;
  }
}