#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include <time.h>
#include <errno.h>

void hex_dump( unsigned char *ptr, int size ) 
{
    static char hex_ascii[] = 
        { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
    int i;
    unsigned char line[80];
    unsigned char *ascii, *hex;
    unsigned char *endptr;
    static unsigned long offset = 0;

    endptr = ptr + size;
    memset( line, ' ', 80 );
    line[69] = 0;
    while( ptr != endptr ) {
        hex = &line[2];
        ascii = &line[52];
        for( i = 0; i < 16; i++ ) {
            if( isprint( *ptr ) ) {
                *ascii++ = *ptr;
            }
            else {
                *ascii++ = '.';
            }
            *hex++ = hex_ascii[*ptr >> 4];
            *hex++ = hex_ascii[*ptr & 0x0f];
            *hex++ = ' ';
            ptr++;
            if( ptr == endptr ) {
                /* clean out whatever is left from the last line */ 
                memset( hex, ' ', ( 15 - i ) * 3 );
                memset( ascii, ' ', 15 - i );
                break;
            }
        }
        printf( "%#08lx %s\n", offset, line );
        offset += 16;
    }
}

#define MAX_BUFFER 128
unsigned char buffer[MAX_BUFFER];

int main( int argc, char **argv ) 
{
    FILE * infile;
    int len;

    if( argc > 1 ) {
        infile = fopen( argv[1], "rb" );
        if( infile == NULL ) {
            fprintf( stderr, "unable to open %s : %s\n", argv[1], strerror(errno) );
            exit(1);
        }
        while( !feof( infile ) ) {
            len = fread( buffer, 1, MAX_BUFFER, infile );
            hex_dump( buffer, len );
        }
        fclose( infile );
    }
    
    else {
        while( !feof( stdin ) ) {
            len = fread( buffer, 1, MAX_BUFFER, stdin );
            hex_dump( buffer, len );
        }
    }
    return 0;
}