/* * comm.c * * These functions perform serial I/O action on IBM PC */ #include #include #include #include "comm.h" /* Globals */ static void (interrupt far * oldvec) (); void interrupt serint (); static uint intv; /* interrupt number to usurp */ static int dat8250, /* 8250 data register */ stat8250, /* 8250 line-status register */ com8250, /* 8250 line-control register */ c_in_buf = 0, /* count of characters received */ xoffpt, /* amount of buffer that forces XOFF */ xonpt, /* amount of buffer that unXOFFs */ xonxoff = 0, /* auto xon/xoff support flag */ xofsnt = 0, /* XOFF transmitted flag */ xofrcv = 0; /* XOFF received flag */ static char en8259, /* 8259 IRQ enable mask */ dis8259, /* 8259 IRQ disable mask */ buffer[CBS], /* Communications circular buffer */ * inptr = buffer, /* input address of circular buffer */ * outptr = buffer; /* output address of circular buffer */ /* Functions */ void interrupt serint () { * inptr++ = inp (dat8250); /* Store character in buffer */ c_in_buf++; /* and increment count */ if (xonxoff) { /* if xon/xoff auto-support is on */ if (c_in_buf > xoffpt && ! xofsnt) { /* buffer nearly full */ comm_putc (XOFF); /* send an XOFF */ xofsnt = 1; /* and say so */ } } _disable (); /* ints off for ptr change */ if (inptr == & buffer[CBS]) /* wrap buffer input pointer if end */ inptr = buffer; _enable (); outp (0x20, 0x20); /* Generic EOI to 8259 */ } /* installs comm interrupts */ int comm_open (portid, speed) int portid; uint speed; { uint be = _bios_equiplist (); /* to get # installed serial ports */ be <<= 4; /* shift-wrap high bits off */ be >>= 13; /* shift down to low bits */ if (be >= portid) { if (portid == 1) { dat8250 = MDMDAT1; stat8250 = MDMSTS1; com8250 = MDMCOM1; dis8259 = MDMINTC; en8259 = MDMINTO; intv = MDMINTV; } else if (portid == 2) { dat8250 = MDMDAT2; stat8250 = MDMSTS2; com8250 = MDMCOM2; dis8259 = MDINTC2; en8259 = MDINTO2; intv = MDINTV2; } else return (0); dobaud (speed); /* set baud */ inptr = outptr = buffer; /* set circular buffer values */ c_in_buf = 0; oldvec = _dos_getvect (intv); /* Save old int vector */ _dos_setvect (intv, serint); /* Set up SERINT as com ISR */ outp (com8250, 0x03); /* 8 bits no parity, 1 stop */ outp (com8250 + 1, 0x0B); /* Assert OUT2, RTS, and DTR */ inp (dat8250); outp (dat8250 + 1, 0x01); /* Receiver-Data-Ready int */ /* Enable 8259 interrupts */ outp (INTCONT, en8259 & inp (INTCONT)); xoffpt = CBS / 50 * 49; /* chars in buff to send XOFF */ xonpt = CBS - xoffpt; /* chars in buff to send XON */ } else be = 0; return ((int) be); } static void dobaud (baudrate) uint baudrate; { uchar portval, blo, bhi; switch (baudrate) { /* Baud rate LSB's and MSB's */ case 50 : bhi = 0x9; blo = 0x00; break; case 75 : bhi = 0x6; blo = 0x00; break; case 110 : bhi = 0x4; blo = 0x17; break; case 150 : bhi = 0x3; blo = 0x00; break; case 300 : bhi = 0x1; blo = 0x80; break; case 600 : bhi = 0x0; blo = 0xC0; break; case 1200 : bhi = 0x0; blo = 0x60; break; case 1800 : bhi = 0x0; blo = 0x40; break; case 2000 : bhi = 0x0; blo = 0x3A; break; case 2400 : bhi = 0x0; blo = 0x30; break; case 4800 : bhi = 0x0; blo = 0x18; break; case 9600 : bhi = 0x0; blo = 0x0C; break; case 19200 : bhi = 0x0; blo = 0x06; break; default : return; } portval = inp (com8250); /* read Line-Control Reg val */ outp (com8250, portval | 0x80); /* set high bit for baud init */ outp (dat8250, blo); /* Send LSB for baud rate */ outp (dat8250 + 1, bhi); /* Send MSB for baud rate */ outp (com8250, portval); /* Reset initial value at LCR */ } /* restore previous settings of 8259 */ void comm_close () { /* Disable com interrupt at 8259 */ outp (INTCONT, dis8259 | inp (INTCONT)); _dos_setvect (intv, oldvec); /* Reset original interrupt vector */ } /* returns # characters available in buffer */ int comm_avail () { return (c_in_buf); } /* send a char out port */ void comm_putc (c) uchar c; { while ((inp (stat8250) & 0x20) == 0) ; /* Wait until transmitter is ready */ outp (dat8250, c); /* then send it */ } /* get a char from buffer */ int comm_getc () { register char * ptr; int c; if (c_in_buf < xonpt && xofsnt) { /* Check if we need to send */ xofsnt = 0; /* an XON to the host after */ comm_putc (XON); /* we had to send an XOFF */ } while (c_in_buf == 0 && ! kbhit ())/* If character not ready and no key hit on keyboard*/ ; /* then wait til character is available*/ ptr = outptr; c = * ptr++; /* Get next character in circular buff */ if (ptr == & buffer[CBS]) /* Check for end of circular buffer */ ptr = buffer; /* start from bottom of buff */ _disable (); /* no interrupts during pointer manips */ outptr = ptr; /* set character output pointer */ c_in_buf--; /* and decrement the character count */ _enable (); /* then allow interrupts to continue */ return (c); /* Return the character */ } /* flush all chars out of buffer */ void comm_flush () { if (xofsnt) { /* Check if XON needs to be sent */ xofsnt = 0; comm_putc (XON); } _disable (); /* no interrupts during pointer manips */ inptr = outptr = buffer; /* reset buffer pointers */ c_in_buf = 0; /* and indicate no chars received */ _enable (); } /* * data read (dread), read data from the circular buffer */ int dread (buffer, wanted, seconds) uchar * buffer; int wanted, seconds; { register int i; long start; int pending, elapsed; start = time ((long *) NULL); for (;;) { pending = comm_avail (); if (pending >= wanted) { /* got enough in the buffer? */ for (i = 0; i < wanted; i++) * buffer++ = comm_getc (); return TRUE; } else { elapsed = time ((long *) NULL) - start; if (elapsed >= seconds) return FALSE; } } } int dput (ptr) unsigned char * ptr; { while (* ptr) comm_putc (* ptr++); } int dgets (buffer) uchar * buffer; { char * ptr; ptr = buffer; while (! kbhit ()) { * buffer = comm_getc (); /* get char if there */ if (* buffer++== 0x0d && ptr != buffer) { * buffer = 0; break; } } }