DOS下串口收发例程

#define DEBUG /* comment me to eliminate main() /* From CompuServe's BPROGB Borland Int'l forum * * #: 11879 S4/Turbo C * 02-Jun-88 18:54:50 * Sb: #11817-VT100 * Fm: Jerry Joplin 70441,2627 * To: Pete Gontier 72261,1754 (X) * * Pete, here are the communication ISR's I've been using. Hope these * don't overflow the message data base for BPROGB. :-) * I think all is included to set up COM1/COM2 for receiver interrupts. * * Also, these are straight ports from routines in MSKERMIT 2.30 and CKERMIT * for UNIX, which are public domain but copyrighted (c) by Columbia * University. */ /* Modification, to support other compiler(s): * Pete Gontier, July 20th, 1988 * This code is no longer portable to the UNIX systems mentioned. * The function names were in accordance with the TT teletype conventions, * and I couldn't stand for it. So sue me. */ /* Modification, to support comm ports 3 & 4 * Al Sharpe, June 7, 1989 * Minor changes added to handle DTR on port close. * * New function added : * flsh_dtr( ) - drops DTR for 200 milliseconds * * Old function modified : * comm_getc( unsigned seconds ) - (1) gets a char from input buffer * with timeout * (2) if a key is pressed a Timeout * is returned */ /* Last modification by Al Sharpe, April 28, 1990. * * - corrected comm_close() to drop RTS and DTR, not just DTR. * - correct flsh_dtr( ) to drop only DTR and leave RTS active. * - flsh_dtr( ) duration extented to 1/2 second. * - correct all bugs in function main( ) so test program will work. * - removed global CARRIER as it was redundant. * - conio.h added for cprintf( ) function. */ #include <dos.h> #include <bios.h> #include <conio.h> #define TCICOMM /* avoid extern declaration in... */ #include "comm.h" /* comm prototypes */ /** macros for absolute data ************************************************/ #define MDMDAT1 0x03F8 /* Address of modem port 1 data */ #define MDMSTS1 0x03FD /* Address of modem port 1 status */ #define MDMCOM1 0x03FB /* Address of modem port 1 command */ #define MDMDAT2 0x02F8 /* Address of modem port 2 data */ #define MDMSTS2 0x02FD /* Address of modem port 2 status */ #define MDMCOM2 0x02FB /* Address of modem port 2 command */ #define MDMDAT3 0x03E8 /* Address of modem port 3 data */ #define MDMSTS3 0x03ED /* Address of modem port 3 status */ #define MDMCOM3 0x03EB /* Address of modem port 3 command */ #define MDMDAT4 0x02E8 /* Address of modem port 4 data */ #define MDMSTS4 0x02ED /* Address of modem port 4 status */ #define MDMCOM4 0x02EB /* Address of modem port 4 command */ #define MDMINTV 0x000C /* Com 1 & 3 interrupt vector */ #define MDINTV2 0x000B /* Com 2 & 4 interrupt vector */ #define MDMINTO 0x0EF /* Mask to enable IRQ3 for port 1 & 3 */ #define MDINTO2 0x0F7 /* Mask to enable IRQ4 for port 2 & 4 */ #define MDMINTC 0x010 /* Mask to Disable IRQ4 for port 1 & 3 */ #define MDINTC2 0x008 /* Mask to Disable IRQ3 for port 2 & 4 */ #define INTCONT 0x0021 /* 8259 interrupt controller ICW2-3 */ #define INTCON1 0x0020 /* Address of 8259 ICW1 */ #define CBS 2048 /* Communications port buffer size */ #define XOFF 0x13 /* XON/XOFF */ #define XON 0x11 #define CARRIER_ON 0x80 /* Return value for carrier detect */ /** globals not externally accessible ***************************************/ static int MODEM_STAT; /* 8250 modem status register */ static int dat8250; /* 8250 data register */ static int stat8250; /* 8250 line-status register */ static int com8250; /* 8250 line-control register */ static char en8259; /* 8259 IRQ enable mask */ static char dis8259; /* 8259 IRQ disable mask */ static unsigned int intv; /* interrupt number to usurp */ static char buffer[CBS]; /* Communications circular buffer */ static char *inptr; /* input address of circular buffer */ static char *outptr; /* output address of circular buffer */ static int c_in_buf = 0; /* count of characters received */ static int xoffpt; /* amount of buffer that forces XOFF */ static int xonpt; /* amount of buffer that unXOFFs */ static void interrupt ( far *oldvec ) ( ); /* vector of previous comm interrupt */ int xonxoff = 0; /* auto xon/xoff support flag */ int xofsnt = 0; /* XOFF transmitted flag */ int xofrcv = 0; /* XOFF received flag */ void interrupt serint ( void ) { /* ISR to receive character */ *inptr++ = inportb ( 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 ) { /* then if buf nearly full */ comm_putc ( XOFF ); /* send an XOFF */ xofsnt = 1; /* and say so */ } } disable ( ); /* ints off for ptr change */ if ( inptr == &buffer[CBS] ) /* Set buffer input pointer */ inptr = buffer; enable ( ); outportb ( 0x20, 0x20 ); /* Generic EOI to 8259 */ } void comm_close ( void ) { /* restore previous settings of 8259 */ outportb ( com8250 + 1, 0x08 ); /* Drop OUT2 */ outportb ( com8250 + 1, 0x00 ); /* Drop DTR and RTS /* outportb ( INTCONT, dis8259 | inportb ( INTCONT ) ); /* Disable com interrupt at 8259 */ setvect ( intv, oldvec ); /* Reset original interrupt vector */ } void dobaud ( unsigned baudrate ) { /* parses baud integer to mask, * re-inits port accordingly */ unsigned char portval; unsigned char 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 = inportb ( com8250 ); /* read Line-Control Reg val */ outportb ( com8250, portval | 0x80 ); /* set high bit for baud init */ outportb ( dat8250, blo ); /* Send LSB for baud rate */ outportb ( dat8250 + 1, bhi ); /* Send MSB for baud rate */ outportb ( com8250, portval ); /* Reset initial value at LCR */ } /* installs comm interrupts */ int comm_open ( int portid, unsigned speed ) { int be = biosequip ( ); /* to get # installed serial ports */ be <<= 4; /* shift-wrap high bits off */ be >>= 13; /* shift down to low bits */ i