DOS系统下的串口键盘编程驱动

/*------------------------------------------------------------------* SERIAL.CPP The following code shows how to take advantage of some of the Turbo C++ extensions to the C++ language to do asynchronous communications without having to write supporting assembly- language routines. This program bypasses the less-than-adequate PC BIOS communications routines and installs a serial interrupt handler. Direct access to PC hardware allows the program to run at faster baud rates and eliminates the need for the main program to continuously poll the serial port for data; thus implementing background communications. Data that enters the serial port is stored in a circular buffer. * Compile this program with Test Stack Overflow OFF. *------------------------------------------------------------------*/ #include <dos.h> #include <conio.h> #include <stdio.h> #include <string.h> #include "serial.h" #include "..\wba\gw\CusType.h" #include "..\UnGetch\UnGetch.h" #define VERSION 0x0101 #define FALSE 0 #define TRUE 1 #define NOERROR 0 /* No error */ #define BUFOVFL 1 /* Buffer overflowed */ #define ESC 0x1B /* ASCII Escape character */ #define ASCII 0x007F /* Mask ASCII characters */ #define SBUFSIZ 0x0010 /* Serial buffer size */ int SError = NOERROR; int portbase = 0; void interrupt(*oldvects[2])(...); static char ccbuf[SBUFSIZ]; unsigned int startbuf = 0; unsigned int endbuf = 0; UINT KeyCode = 0; /* Handle communications interrupts and put them in ccbuf */ void interrupt com_int(...) { disable(); /* if ((inportb(portbase + IIR) & RX_MASK) == RX_ID) { if (((endbuf + 1) & SBUFSIZ - 1) == startbuf) SError = BUFOVFL; ccbuf[endbuf++] = inportb(portbase + RXR); endbuf &= SBUFSIZ - 1; } */ /* Put the serial code into keyboard buffer */ KeyCode = inportb(portbase + RXR); if(KeyCode != 0x0a) //ignores the linefeed character '\n' { if(KeyCode == 0x0d) KeyCode = 0x1c0d; UnGetch(KeyCode); } /* Signal end of hardware interrupt */ outportb(ICR, EOI); enable(); } /* Output a character to the serial port */ serial& serial::operator<<( char x ) { long int timeout = 0x0000FFFFL; outportb(portbase + MCR, MC_INT | DTR | RTS); /* Wait for Clear To Send from modem */ while ((inportb(portbase + MSR) & CTS) == 0) if (!(--timeout)) return *this; timeout = 0x0000FFFFL; /* Wait for transmitter to clear */ while ((inportb(portbase + LSR) & XMTRDY) == 0) if (!(--timeout)) return *this; disable(); outportb(portbase + TXR, x); enable(); return *this; } /* Output a string to the serial port */ serial& serial::operator<<( char *string ) { while (*string) { (*this) << *string; string++; } return *this; } /* This routine returns the current value in the buffer */ serial &serial::operator>>( char &ch ) { if (endbuf == startbuf) { ch = -1; return *this; } ch = ccbuf[startbuf]; startbuf++; startbuf %= SBUFSIZ; return *this; } /* Install our functions to handle communications */ void setvects(void) { oldvects[0] = getvect(0x0B); oldvects[1] = getvect(0x0C); setvect(0x0B, com_int); setvect(0x0C, com_int); } /* Uninstall our vectors before exiting the program */ void resvects(void) { setvect(0x0B, oldvects[0]); setvect(0x0C, oldvects[1]); } /* Turn on communications interrupts */ void i_enable(int pnum) { int c; disable(); c = inportb(portbase + MCR) | MC_INT; outportb(portbase + MCR, c); outportb(portbase + IER, RX_INT); c = inportb(IMR) & (pnum == COM1 ? IRQ4 : IRQ3); outportb(IMR, c); enable(); } /* Turn off communications interrupts */ void i_disable(void) { int c; disable(); c = inportb(IMR) | ~IRQ3 | ~IRQ4; outportb(IMR, c); outportb(portbase + IER, 0); c = inportb(portbase + MCR) & ~MC_INT; outportb(portbase + MCR, c); enable(); } /* Tell modem that we're ready to go */ void comm_on(void) { int c, pnum; pnum = (portbase == COM1BASE ? COM1 : COM2); i_enable(pnum); c = inportb(portbase + MCR) | DTR | RTS; outportb(portbase + MCR, c); } /* Go off-line */ void serial::comm_off(void) { i_disable(); outportb(portbase + MCR, 0); } void serial::init_serial(void) { endbuf = startbuf = 0; setvects(); comm_on(); } serial::~serial() { comm_off(); resvects(); } /* Set the port number to use */ int serial::SetPort(int Port) { int Offset, far *RS232_Addr; switch (Port) { /* Sort out the base address */ case COM1 : Offset = 0x0000; break; case COM2 : Offset = 0x0002; break; default : return (-1); } RS232_Addr = (int far *)MK_FP(0x0040, Offset); /* Find out where the port is. */ if (*RS232_Addr == NULL) return (-1);/* If NULL then port not used. */ portbase = *RS232_Addr; /* Otherwise set portbase */ return (0); } /* This routine sets the speed; will accept funny baud rates. */ /* Setting the speed requires that the DLAB be set on. */ int serial::SetSpeed(int Speed) { char c; int divisor; if (Speed == 0) /* Avoid divide by zero */ return (-1); else divisor = (int) (115200L/Speed); if (portbase == 0) return (-1); disable(); c = inportb(portbase + LCR); outportb(portbase + LCR, (c | 0x80)); /* Set DLAB */ outportb(portbase + DLL, (divisor & 0x00FF)); outportb(portbase + DLH, ((divisor >> 8) & 0x00FF)); outportb(portbase + LCR, c); /* Reset DLAB */ enable(); return (0); } /* Set other communications parameters */ int serial::SetOthers(int Parity, int Bits, int StopBit) { int setting; if (portbase == 0) return (-1); if (Bits < 5 || Bits > 8) return (-1); if (StopBit != 1 && StopBit != 2) return (-1); if (Parity != NO_PARITY && Parity != ODD_PARITY && Parity != EVEN_PARITY) return (-1); setting = Bits-5; setting |= ((StopBit == 1) ? 0x00 : 0x04); setting |= Parity; disable(); outportb(portbase + LCR, setting); enable(); return (0); } /* Set up the port */ serial::serial(int Port, int Speed, int Parity, int Bits, int StopBit) { flag = 0; if (SetPort(Port)) flag = -1; if (SetSpeed(Speed)) flag = -1; if (SetOthers(Parity, Bits, StopBit)) flag = -1; if (!flag) init_serial(); } /* Control-Break interrupt handler */ int c_break(void) { i_disable(); fprintf(stderr, "\nStill online.\n"); return(0); }