// Created:10-23-98
// By Jeff Connelly

// Hex encoding/decoding, same purpose as UUE/XXE.

// Converts a binary file to a plain text file containing hex digits, two
// per byte.  Very inefficent, the file size is doubled!  Fast, simple.

#include "stdafx.h"
#define EXPORTING
#include "comprlib.h"

#include <stdio.h>

#define ddig(c) ((c) >= 0x0 && (c) <= 0x9)
#define hdig(c) ((c) >= 0xA && (c) <= 0xF)
#define MASK   0x0F

#define dchr(c) ((c) >= '0' && (c) <= '9')      // Decimal character?
#define hchr(c) ((c) >= 'A' && (c) <= 'F')      // Hexadecimal letter?

#define CLEAR   printf ("\033X");
#define BELL    printf ("\007");

// Convert an integer 'c' to a hex string 's' 
static char* itohex (register unsigned char c, register char *s)
{
    register char c1, c2;

    c1 = (c >> 4) & MASK;
    c2 = c & MASK;

    s[0] = ddig(c1) ? (c1 + '0') : (hdig(c1) ? (c1 - 0xA + 'A') : c1);
    s[1] = ddig(c2) ? (c2 + '0') : (hdig(c2) ? (c2 - 0xA + 'A') : c2);
    s[2] = 0;

    return s;
}

// Converts a hex string to an integer
static char hextoi(register char c1, register char c2)
{
    register char i;

    i = dchr(c1) ? c1 - '0' : (hchr(c1) ? c1 - 'A' + 0xA : c1);
    return (i << 4) + (dchr(c2) ? c2 - '0' : (hchr(c2) ? c2 - 'A' + 0xA : c2));
}

// Encode stream using "hex" scheme
void EXPORT hex_encode()
{
    // A byte is encoded in two hex digits
    register char a, b, c;
    register char* s = "abc";

    while (!end_of_data())
    {
        s[0] = 0;
        s[1] = 0;
        c = read_byte();
        s = itohex(c, s);
        a = s[0];
        b = s[1];
        write_byte(a);
        write_byte(b);
    }
}
        
// Decode hex-encoded data
void EXPORT hex_decode()
{
    // A byte is repersented in two hex digits
    register char a, b;

    while (!end_of_data())
    {
        a = read_byte();
        if (end_of_data())
            break;
        b = read_byte();

        write_byte(hextoi(a, b));
    }
}