#include #include #define COM_PORT 2 /* serial port definitions for COM2 */ #define COMPARMS 0x83 /* comm. parameters for 1200-n-8-1 */ #include "serial.h" /* definitions and constants for this program */ main() /* main program initializes the hardware, then enters a */ { /* loop where it moves characters from receive serial port */ int ch; /* to screen, and from keyboard to transmit serial port */ install(); /* install interrupt handler, initialize COM port */ atexit(cleanup);/* post removal routine to execute at program end */ while( 1 ) { /* main program loop, repeat over and over */ while ((ch = sgetch()) != S_EOF) { /* if serial char available */ putch(ch); /* put it on the screen */ if (translation && ch == '\r') /* if translation in effect */ putch('\n'); /* add line feeds to C/R's */ } if (kbhit()) { /* keyboard handler, execute if key has been hit */ ch = getch(); /* read the character from the keyboard */ if (ch == 0) /* if zero, next character is scan code */ switch (ch = getch()) { /* read scan code from the keyboard */ case 0x12: /* if character is Alt-E */ echo = !echo; /* toggle the screen echo */ if (echo) printf("\nEcho on.\n"); else printf("\nEcho off.\n"); break; case 0x14: /* if character is Alt-T */ translation = !translation; /* toggle the translation */ if (translation) printf("\nTranslation on.\n"); else printf("\nTranslation off.\n"); break; /* if character is Alt-S */ case 0x1f: /* print the modem status */ ch = inportb(ACE_MODEM_STAT_REG); /* get current status */ printf("\nStatus: DCD=%1d DSR=%1d CTS=%1d\n", (ch & DCD) ? 1:0, (ch & DSR) ? 1:0, (ch & CTS) ? 1:0); if (break_detect || frame_error || char_overrun || parity_error) { printf("Errors:\n"); /* error report */ printf(" overrun = %4d\n", char_overrun); printf(" frame error = %4d\n", frame_error ); printf(" break detect = %4d\n", break_detect); printf(" parity error = %4d\n", parity_error); break_detect = frame_error = char_overrun = parity_error = 0; } else printf("No errors.\n"); if (echo) printf("Echo on.\n"); if (translation) printf("Translation on.\n"); break; case 0x2d: /* if character is Alt-X */ exit(); /* terminate the program */ } else { /* otherwise, the character was a normal character */ sputch(ch); /* so send it to the serial transmitter */ if (echo) { /* if echo is on */ putch(ch); /* echo char to the screen */ if (ch == '\r') putch('\n'); /* add line feeds to C/R's */ } } } /* end of keyboard handler */ if (ring_detect) { /* if ring is detected, beep the speaker */ putch('\a'); /* requires modem cable pin 22 connected */ ring_detect = 0; /* then reset ring detect for next time */ } } } void interrupt serial_isr(void) /* interrupt service routine */ { /* executed when receive data is */ char ch; /* available, or when line status */ int temp_index; /* or modem status changes */ enable(); /* re-enable the other interrupts */ ch = inportb(ACE_INT_IDENT_REG); /* examine IIR for cause of int. */ switch (ch) { case 6: /* if line status interrupt */ ch = inportb(ACE_LINE_STAT_REG); /* read line status register */ if (ch & PE) parity_error++; /* then increment the error */ if (ch & OE) char_overrun++; /* counters according to */ if (ch & FE) frame_error++; /* which error bits are set */ if (ch & BI) break_detect++; inportb(ACE_DATA_REG); /* read the data register to empty it */ break; case 4: /* if received data available */ ch = inportb(ACE_DATA_REG); /* read character from the ACE */ temp_index = input_index + 1; /* temporary value */ if (temp_index >= QUELEN) /* test for index past buf. end */ temp_index = 0; /* if so, reset to beginning */ if (temp_index != output_index) { /* test for queue overflow */ queue[temp_index] = ch; /* put character into queue */ input_index = temp_index; /* and update the index */ } /* if the queue overflows, characters are lost */ break; case 0: /* if modem status interrupt */ ch = inportb(ACE_MODEM_STAT_REG); /* read modem status reg. */ if (ch & DCTS) { /* if clear to send changed */ /* a routine to handle CTS changes may go here */ } if (ch & DDSR) { /* if data set ready changed */ /* a routine to handle DSR changes may go here */ } if (ch & TERI) { /* if trailing edge ring indicator was */ ring_detect = 1; /* asserted, turn on ring detect */ } if (ch & DDCD) { /* if data carrier detect changed */ /* a routine to handle DCD changes may go here */ } } outportb(PIC_CTL_REG, NON_SPEC_EOI); /* finally, send the */ /* non-specific EOI to re-enable the PIC */ } int sgetch(void) /* read a character from the serial input buffer */ { char ch; int temp_index; /* temporary index value avoids a conflict with */ /* interrupt routine updating the same variable */ if (output_index != input_index) { /* test for char. available */ temp_index = output_index + 1; /* increment temporary index */ if (temp_index >= QUELEN) /* is index past buffer end ? */ temp_index = 0; /* if so, reset to beginning */ ch = queue[temp_index]; /* get character from buffer */ output_index = temp_index; /* update the output index */ return(ch); /* character is return value */ } else return(S_EOF); /* if no chars available, return serial EOF */ } void sputch(char ch) /* output a character to serial transmitter */ { while( inportb(ACE_LINE_STAT_REG) & THRE == 0 ) /* buffer empty ? */ ; /* if transmit buffer not empty, wait, do nothing */ outportb(ACE_DATA_REG, ch); /* when empty, send char to the 8250 */ } void install(void) /* installs the interrupt service routine and */ { /* initializes the 8250 for active communications */ char ch; bioscom(0, COMPARMS, COM_PORT - 1); /* set communications params. */ /* enable ACA modem status, line status & receive data interrupts */ outportb(ACE_INT_ENB_REG, 0xd); /* enable modem/line/rcvdata ints */ inportb(ACE_DATA_REG); /* empty receive data register */ inportb(ACE_LINE_STAT_REG); /* clear the line status register */ old_vector = getvect(COM_INT_NUM); /* save previous int. vector */ setvect(COM_INT_NUM, *serial_isr); /* set vector to our routine */ ch = inportb(PIC_INT_MASK_REG); /* get current interrupt mask */ ch &= IRQ_MASK; /* unmask our IRQ (set it to 0) */ outportb(PIC_INT_MASK_REG, ch); /* and write it back to the PIC */ outportb(ACE_MODEM_CTL_REG, 0xb); /* set RTS, DTR to enable modem */ /* and turn on OUT2 to enable the 8250's IRQ interrupt to system */ printf("\nCOM%d initialized.\n", COM_PORT); /* sign-on message */ } void cleanup(void) /* routine resets the serial port at exit time */ { char ch; outportb(ACE_INT_ENB_REG, 0); /* disable all 8250 interrupts */ outportb(ACE_MODEM_CTL_REG, 0);/* clear RTS, DTR to disable modem */ /* and turn off OUT2 to disable the 8250's IRQ int. to system */ ch = inportb(PIC_INT_MASK_REG); /* get current interrupt mask */ ch |= !IRQ_MASK; /* mask our IRQ (set it to 1) */ outportb(PIC_INT_MASK_REG, ch); /* and write it back to the PIC */ setvect(COM_INT_NUM, old_vector); /* restore previous int. vector */ printf("\nProgram terminated.\n\n"); /* sign-off message */ } /* end of program */