port programming

[bahati]

HI,
i have written the code below. I need help on how to modify the program so that it takes its input (reads) from a file and then the data read from the port is returned to another new file specified by a user. This program has been written to send data to and read from an encrypting circuitry ( stream cipher).

SOFTWARE DESIGN.

/* *******************************************************/
/*This program is intended to WRITE and READ data to and from the SPP port */

/*Author: Mr.Kebungo Dominic. */

/*Date: 8-12 Feb. 2005.
/*Reference:

http://www.bibinjohn.tk

. */

/******************************************************************/
#include <stdio.h> /* required so as to access the filesystem*/
#include <dos.h>
#include <time.h>
#define DATA 0x378 /*Data Register base address*/
#define STATUS DATA+1 /* Status Register address*/
#define CONTROL DATA+2 /*Control Register address*/

main()
{
char s;
char c;
c='A';


outport(CONTROL,inportb(CONTROL)&0xF0|0x04); /*initialise the
CONTROL port for data input*/

outportb(DATA, c); /*write c to the DATA register*/
delay(4);/*allow for propagation delay time*/

s=(inportb(STATUS)&0xF0); /* read MSnibble*/

s=s|(inportb(CONTROL)&0x0F);/*Read LSnibble*/

s=s^0x84; /*toggle bit 2 and 7 */
/*pins 11 and 14 are hardware inverted*/

printf("character: %c becomes: %c\n", c,s);

return (0);

}

 

[Salem]

Well first of all, write a function to do the work

char encrypt ( char c ) {
    char s;
    outport(CONTROL,inportb(CONTROL)&0xF0|0x04);
    /* initialise the CONTROL port for data input*/
    outportb(DATA, c);   /*write c to the DATA register*/
    delay(4);/*allow for  propagation delay time*/

    s=(inportb(STATUS)&0xF0);  /* read MSnibble*/
    s=s|(inportb(CONTROL)&0x0F);/*Read LSnibble*/
    s=s^0x84; /*toggle bit 2 and 7 */
                 /*pins 11 and 14 are hardware inverted*/
    return s;
}

Then your main would be

int main() {
    char c = 'A';
    char s = encrypt(c);
    printf("character: %c becomes: %c\n", c,s);
    return 0;
}

Now all you need do is
- open and close files (fopen, fclose)
- read and write characters (fgetc, fputc)

Oh, and that delay(4) will really hurt your performance when you're reading large files.

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