/* DRIVERS.C */

#include <mem.h>
#include <dos.h>
#include <stdlib.h>     /* ANSI Standard only */
#include <conio.h>
#include <stdio.h>
#include "serial.h"
#include "protocol.h"

#ifndef TRUE
#define TRUE 1
#define FALSE 0
#endif 


/* size of the buffer to use for string incoming characters */
// #define COM_BUF_SIZE (62 * 1024)
#define COM_BUF_SIZE 2048


char *buffer_start;      /* beginning of the buffer */
char *buffer_end;        /* end of the buffer */ /* pointer to next place to put character in */
char *buffer_in;
char *buffer_out;        /* place to get next character from */

int count = 0;        /* number of characters in buffer */
int max_count;       /* max number of chars ever in buffer */


void init_buf(void)
{
	count = 0;
	max_count = 0;

	buffer_start = (char *) malloc( COM_BUF_SIZE );

	if( buffer_start == NULL )
	{
		printf( "\n** Can't malloc in init_buf(%u) **\n", COM_BUF_SIZE);
		exit( 1 );
	}

	buffer_in = buffer_start;
	buffer_out = buffer_start;
	buffer_end = buffer_start + COM_BUF_SIZE - 10;

	memset( buffer_start, '*', COM_BUF_SIZE );
}

/* init -- initialize the port */

/*  buf_getch -- get a character from the buffer
Update buffer_out  Returns  the character or ? if none  */

char buf_getch(void)
{
	char ch;        /* character we got */

	if (count == 0)
		return ('?');

	ch = *buffer_out; buffer_out++;

	if (buffer_out == buffer_end)
		buffer_out = buffer_start;

	disable();
	count--;
	enable();

	return(ch);
}
/*  serial_interrupt -- interrupt handler for serial input
Called in interrupt mode by the hardware when a character is received on the serial input */

//far
void interrupt serial_interrupt()
{
int     int_status;     /* status during interrupt */

	disable();
	int_status = inportb((int)&COM->status);

	/* tell device we have read interrupt */
	(void)inportb((int)&COM->interrupt_enable);
	(void)inportb((int)&COM->interrupt_id);

	if ((int_status & S_RxRDY) == 0) {
		enable();
		return;
	}

	*buffer_in = inportb((int)&COM->data) & 0x7F;
	buffer_in++;

	if (buffer_in == buffer_end)
		buffer_in = buffer_start;

	count++;

	if( count > max_count )
		max_count = count;

	outportb(0x20, 0x20);
	enable();
}