/**
 *  Hexdump.java
 *
 *  Dumps a binary file to a ascii, in hexadecimal.
 *  Copyright (c) 1999,2000 W.Finlay McWalter
 *
 */
import java.io.*;

public class Hexdump {
    private static final int BYTES_PER_LINE = 16;
    private static final int PADDING = 4;
    
    private static void printSpaces(int spaces){
	for(int x = 0; x < spaces; x++){
	    System.out.print(" ");
	}
    }
    
    private static char charFromHexDigit(int digit){
	if((digit >= 0) && (digit <=9))
	    return (char)(digit + '0');
	else
	    return (char)(digit -10 + 'a');
    }
    
    private static void printByte(byte b){
	int i = (b>=0)?b:(256+b);
	System.out.print(charFromHexDigit(i/16));
	System.out.print(charFromHexDigit(i%16) + " ");
    }
    
    /**
     *  Prints an unsigned hex value, with between
     *  1 and 8 digits.
     */
    private static void printUnsignedHex(int i, int digits){
	for(int d=(8-digits); d < digits; d++){
	    int digitValue = (int)(i >> (4*(7-d)))%16;

	    char c = charFromHexDigit((digitValue>=0)?digitValue
				      :(16+digitValue));

	    System.out.print(c);
	}
    }

    private static String MakeStringFromUnsigned(int i, int digits){
	char [] buffer = new char[10];
	for(int d=(8-digits); d < digits; d++){
	    int digitValue = (int)(i >> (4*(7-d)))%16;
	    buffer[d]= charFromHexDigit((digitValue>=0)?digitValue
				      :(16+digitValue));
	}
	return new String(buffer);
    }

    
    private static void dumpFile(FileInputStream in){
	try {
	    byte[] inBuf = new byte[BYTES_PER_LINE]; 
	    int count;
	    while((count = in.read(inBuf)) >0){
		// print offset
		
		// print hex values
		for(int x=0; x<count; x++){
		    printByte(inBuf[x]);
		}
		
		// print padding
		printSpaces(PADDING + ((BYTES_PER_LINE-count)*3));
		
		// print ascii
		for(int x=0; x<count; x++){
		    char v = (char)inBuf[x];
		    if((v >= ' ') && (v < (char)0x7f)){
			System.out.print(v);
		    }
		    else {
			System.out.print(".");
		    }
		}
		
		System.out.println();
	    }
	}
	catch (IOException e){
	    System.out.println("error reading file");
	}
    }
    
    public static final void main (String [] args){
	if(args.length == 1){
	    try {
		FileInputStream inStream = new FileInputStream(args[0]);
		dumpFile(inStream);
		inStream.close();
	    }
	    catch (FileNotFoundException e){
		System.out.println("File \"" + args[0] + "\" not found");
	    }
	    catch (IOException e){
		System.out.println("error closing file");
	    }
	}
	else {
	    System.out.println("usage:\n  java Hexdump <filename>\n");
	}
    }
}