// Created:11-03-98
// By Jeff Connelly

// XXEncoding, similar to UUEncoding.

// XXE should be used instead of UUE because the alphabet is + and - 0-9, A-Z,
// and a-z.  The problems of translation from ASCII to other is fixed in XXE.

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

#define ENC(c) (set[(c) & 077])
// Character set
static char set[] =
    "+-0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

// Output a group of 3 bytes pointed to by 'p'
static void outenc(char* p)
{
    int c1, c2, c3, c4;

    c1 = *p >> 2;
    c2 = (*p << 4) & 060 | (p[1] >> 4) & 017;
    c3 = (p[1] << 2) & 074 | (p[2] >> 6) & 03;
    c4 = p[2] & 077;
    write_byte(ENC(c1));
    write_byte(ENC(c2));
    write_byte(ENC(c3));
    write_byte(ENC(c4));
}

static int fr(char* buf, int cnt)
{
    int c, i;

    for (i = 0; i < cnt; ++i)
    {
        c = read_byte();
        if (end_of_data())
            return i;
        buf[i] = c;
    }
    return cnt;
}

// Single character decoding
#define DEC(c) (table[(c) & 0177])
static char table[128];
static int replace;

// XXEncode to plain text
void xx_encode()
{
    char buf[80];
    int i, n;

    while (true)
    {
        // Read a 1 to 45 character line
        n = fr(buf, 45);
        write_byte(ENC(n));

        for (i = 0; i < n; i += 3)
            outenc(&buf[i]);

        write_byte('\n');

        if (n <= 0)
            break;
    }
}

static void outdec(char* p, int n)
{
    int c1, c2, c3;

    c1 = DEC(*p) << 2 | DEC(p[1]) >> 4;
    c2 = DEC(p[1]) << 4 | DEC(p[2]) >> 2;
    c3 = DEC(p[2]) << 6 | DEC(p[3]);
    if (n >= 1)
        write_byte(c1);

    if (n >= 2)
        write_byte(c2);

    if (n >= 3)
        write_byte(c3);
}

// Decode XXEncoded file
void xx_decode()
{
    char buf[80];
    char* bp;
    int n, i;

    bp = table;
    for (n = 128; n; --n)
        *(bp++) = 0;

    bp = set;
    for (n = 64; n; --n)
        table[*(bp++) & 0177] = 64 - n;

    while (true)
    {
        // Read an input line
        for (i = 0; i < sizeof(buf); ++i)
        {
            buf[i] = read_byte();
            if (end_of_data())
                break;
        }

        n = DEC(buf[0]);
        if (n <= 0)
            break;

        bp = &buf[1];

        while (n > 0)
        {
            if (replace)
                outdec(bp, n);
            bp += 4;
            n -= 3;
        }
    }
}