/*
 * Dumper, by Dan Gookin
 * Displays the contents of a file in
 * hexadecimal and ASCII
 */

#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <ctype.h>
#include <string.h>

void main(int argc,char *argv[])
{
    FILE *dump_me;              //File handle storage
    int i,t,x,b;
    char c;
    char buffer[16];

/* Check to see if a filename was typed */

    if(argc<2)
    {
        puts("Format: DUMPER filename");
        exit(0);
    }

/* Open the file and make sure it's okay */

    dump_me = fopen(argv[1],"rb");
    if(dump_me==NULL)
    {
        printf("Error opening %s\n",argv[1]);
        exit(1);
    }

/*
 * The file is open. It's displayed in upper case using
 * the STRUPR function.
 * Read each byte in the file and display it
 * using the format:
 *
 * OFFSET - 16 HEX bytes - 16 ASCII chars
 *
 * Each row contains 16 hex bytes and 16 ASCII
 * Variable X is the file length counter
 * Variable B counts to 16 for each row
 */

    x = b = 0;

    printf("%s:\n",strupr(argv[1]));

    printf("%0.4X: ",x);        //starting offset = 0

/*
 * The while loop continues until the EOF is encountered.
 * The character read is stored in integer variable I
 */

    while((i=fgetc(dump_me))!= EOF)
    {
        printf("%0.2X ",i);     //show char as 2-digit HEX
        x++;                    //increment file size count
        buffer[b] = i;          //store char in buffer
        b++;                    //increment buffer count

/*
 * X MOD 16 returns ZERO every time X is divisible by 16
 * So you can use if(!(x%16)) to determine whenever 16
 * characters have been read from the file
 */

        if(!(x%16))
        {
            printf("  ");       //two spaces

/*
 * The following displays the ASCII values of the characters
 * read and stored in the BUFFER. The ISCNTRL function
 * determines if the character is a control character. If so,
 * a dot is displayed. Otherwise, the character is displayed.
 */

            for(t=0;t<16;t++)
            {
                if(iscntrl(buffer[t]))
                    putchar('.');
                else
                    putchar(buffer[t]);
            }

/*
 * After the ASCII display, a new line is shown, starting
 * with the offset. Then B is re-initialized back to zero
 */

            printf("\n%0.4X: ",x);
            b = 0;
        }

/* 384 is 24 rows of 16 items--a screen. So after each screen
 * A "Press Enter" message is dispalyed. The same MOD logic
 * is used in this IF comparision.
 * The \R in the PRINTF statement allows the "Press Enter"
 * message to overwrite the initial offset value that would
 * otherwise appear there.
 * The KBHIT function sits and waits for any character to be
 * pressed. However, if the ESC key (code '\x1b') is pressed
 * then the program quits. Otherwise, the offset value is
 * re-printed and the program continues with the next 16
 * characters.
 */

        if(!(x%384))
        {
            printf("\rPress Enter:");
            while(!kbhit())
                ;
            c = getch();
            if(c=='\x1b') exit(0);
            printf("\n%0.4X: ",x);
        }
    }
    fclose(dump_me);            //ALWAYS CLOSE YOUR FILES!

/*
 * Display summary information
 * STRUPR converts the filename to ALL CAPS
 */

    printf("\n%s: size = %u bytes\n",strupr(argv[1]),x);
}