/*
 * Copyright (c) 1995-2001 Kungliga Tekniska Högskolan
 * (Royal Institute of Technology, Stockholm, Sweden).
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * 3. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <stdlib.h>
#include <string.h>

#include "dma.h"

static char base64_chars[] =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

static int
pos(char c)
{
        char *p;
        for (p = base64_chars; *p; p++)
                if (*p == c)
                        return p - base64_chars;
        return -1;
}


int
base64_encode(const void *data, int size, char **str)
{
    char *s, *p;
    int i;
    int c;
    const unsigned char *q;

    p = s = (char *) malloc(size * 4 / 3 + 4);
    if (p == NULL)
        return -1;
    q = (const unsigned char *) data;
    i = 0;
    for (i = 0; i < size;) {
        c = q[i++];
        c *= 256;
        if (i < size)
            c += q[i];
        i++;
        c *= 256;
        if (i < size)
            c += q[i];
        i++;
        p[0] = base64_chars[(c & 0x00fc0000) >> 18];
        p[1] = base64_chars[(c & 0x0003f000) >> 12];
        p[2] = base64_chars[(c & 0x00000fc0) >> 6];
        p[3] = base64_chars[(c & 0x0000003f) >> 0];
        if (i > size)
            p[3] = '=';
        if (i > size + 1)
            p[2] = '=';
        p += 4;
    }
    *p = 0;
    *str = s;
    return strlen(s);
}

#define DECODE_ERROR 0xffffffff

static unsigned int
token_decode(const char *token)
{
        int i;
        unsigned int val = 0;
        int marker = 0;
        if (strlen(token) < 4)
                return DECODE_ERROR;
        for (i = 0; i < 4; i++) {
                val *= 64;
                if (token[i] == '=')
                        marker++;
                else if (marker > 0)
                        return DECODE_ERROR;
                else
                        val += pos(token[i]);
        }
        if (marker > 2)
                return DECODE_ERROR;
        return (marker << 24) | val;
}

int
base64_decode(const char *str, void *data)
{
        const char *p;
        unsigned char *q;

        q = data;
        for (p = str; *p && (*p == '=' || strchr(base64_chars, *p)); p += 4) {
                unsigned int val = token_decode(p);
                unsigned int marker = (val >> 24) & 0xff;
                if (val == DECODE_ERROR)
                        return -1;
                *q++ = (val >> 16) & 0xff;
                if (marker < 2)
                        *q++ = (val >> 8) & 0xff;
                if (marker < 1)
                        *q++ = val & 0xff;
        }
        return q - (unsigned char *) data;
}