88 lines
2 KiB
C
Executable file
88 lines
2 KiB
C
Executable file
#include <stdio.h>
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#include <dos.h>
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#include "serial.h"
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int comport = 0;
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#define SER_LATCH_LO 0
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#define SER_LATCH_HI 1
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#define SER_TX 0
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#define SER_RX 0
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#define SER_IER 1
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#define SER_LCR 3
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#define SER_MCR 4
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#define SER_LSR 5
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#define PIC1 0x20
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#define OCW1 0x21
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#define PIC_EOI 0x20
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// COM1 - IRQ4, COM2 - IRQ3, COM3 - IRQ4, COM4 - IRQ3
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#define SER_IRQ(port) (4 - (port % 2))
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#define SER_VECTOR(irq) (0x08 + (irq))
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static char readbuf[SER_READ_BUFFER_SIZE];
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static int ireadbufStart = 0;
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static volatile int ireadbufLim = 0;
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static int irq = 0;
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static void interrupt (*oldSerISR)() = NULL;
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static void interrupt ser_isr() {
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while (inp(comport + SER_LSR) & 0x01) {
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readbuf[ireadbufLim] = inp(comport + SER_RX);
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ireadbufLim = (ireadbufLim + 1) % SER_READ_BUFFER_SIZE;
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}
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outp(PIC1, PIC_EOI);
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}
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static void ser_cleanup() {
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if (irq) {
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int ocw = inp(OCW1) | (1 << irq);
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outp(OCW1, ocw);
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setvect(SER_VECTOR(irq), oldSerISR);
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irq = 0;
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}
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}
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void ser_init(int port, int baudrate, int protocol) {
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int far *comport_addr = MK_FP(0x0040, 0x0000);
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int lcr, ocw;
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comport = comport_addr[port];
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irq = SER_IRQ(port);
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outp(comport + SER_LCR, 0x80);
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outp(comport + SER_LATCH_HI, baudrate >> 8);
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outp(comport + SER_LATCH_LO, baudrate & 0xff);
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outp(comport + SER_LCR, protocol);
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outp(comport + SER_MCR, 0x0b);
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oldSerISR = getvect(SER_VECTOR(irq));
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setvect(SER_VECTOR(irq), ser_isr);
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ocw = inp(OCW1) & ~(1 << irq);
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outp(OCW1, ocw);
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outp(comport + SER_IER, 0x01);
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atexit(ser_cleanup);
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}
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int ser_poll() {
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int result = SER_NODATA;
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if (ireadbufStart != ireadbufLim) {
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result = readbuf[ireadbufStart];
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ireadbufStart = (ireadbufStart + 1) % SER_READ_BUFFER_SIZE;
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}
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return result;
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}
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void ser_write_byte(char byte) {
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while (!(inp(comport + SER_LSR) & 0x20)) {}
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outp(comport + SER_TX, byte);
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}
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void ser_write(char *str) {
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for (; *str; str ++) {
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ser_write_byte(*str);
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}
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}
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