/*==LICENSE==*

CyanWorlds.com Engine - MMOG client, server and tools
Copyright (C) 2011  Cyan Worlds, Inc.

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

You can contact Cyan Worlds, Inc. by email legal@cyan.com
 or by snail mail at:
      Cyan Worlds, Inc.
      14617 N Newport Hwy
      Mead, WA   99021

*==LICENSE==*/
/*****************************************************************************
*
*   $/Plasma20/Sources/Plasma/NucleusLib/pnUtils/Private/pnUtBase64.cpp
*   
***/

#include "../Pch.h"
#pragma hdrstop


/*****************************************************************************
*
*   Private
*
***/

static const char kEncode64[] = {
//   0000000000111111111122222222223333333333444444444455555555556666
//   0123456789012345678901234567890123456789012345678901234567890123
    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
};

// Note that the decode table contains one special entry:
// The '-' character (0x2d) maps to 63 just like '/' (0x2f)
// so that URLs will work with Base64Decode when we implement them.
#define kTerminator 127
#define xx kTerminator
static const char kDecode64[] = {
//   0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15
    xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,
    xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,
    xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,62,xx,63,xx,63,
    52,53,54,55,56,57,58,59,60,61,xx,xx,xx,xx,xx,xx,
    xx, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10,11,12,13,14,
    15,16,17,18,19,20,21,22,23,24,25,xx,xx,xx,xx,xx,
    xx,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,
    41,42,43,44,45,46,47,48,49,50,51,xx,xx,xx,xx,xx,
    xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,
    xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,
    xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,
    xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,
    xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,
    xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,
    xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,
    xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,
};
#undef xx

static const char kFillchar = '=';


/*****************************************************************************
*
*   Exports
*
***/

//============================================================================
unsigned Base64Encode (
    unsigned    srcChars,
    const byte  srcData[],
    unsigned    dstChars,
    char *      dstData
) {
    ASSERT(srcData);
    ASSERT(dstChars >= Base64EncodeSize(srcChars));
    ASSERT(dstData);
    
    ref(dstChars);

    const char * dstBase = dstData;
    const byte * srcTerm = srcData + srcChars;
    for (;;) switch (srcTerm - srcData) {
        case 0:
            *dstData++ = 0;
        return dstData - dstBase;

        case 1:
            *dstData++ = kEncode64[ ((srcData[0] >> 2) & 0x3f) ];
            *dstData++ = kEncode64[ ((srcData[0] << 4) & 0x30) ];
            *dstData++ = kFillchar;
            *dstData++ = kFillchar;
            *dstData++ = 0;
        return dstData - dstBase;

        case 2:
            *dstData++ = kEncode64[ ((srcData[0] >> 2) & 0x3f) ];
            *dstData++ = kEncode64[ ((srcData[0] << 4) & 0x30) + ((srcData[1] >> 4) & 0x0f) ];
            *dstData++ = kEncode64[ ((srcData[1] << 2) & 0x3c) ];
            *dstData++ = kFillchar;
            *dstData++ = 0;
        return dstData - dstBase;

        default:
            *dstData++ = kEncode64[ ((srcData[0] >> 2) & 0x3f) ];
            *dstData++ = kEncode64[ ((srcData[0] << 4) & 0x30) + ((srcData[1] >> 4) & 0x0f) ];
            *dstData++ = kEncode64[ ((srcData[1] << 2) & 0x3c) + ((srcData[2] >> 6) & 0x03) ];
            *dstData++ = kEncode64[ (srcData[2] & 0x3f) ];
            srcData   += 3;
        break;
    }
}

//============================================================================
unsigned Base64Decode (
    unsigned    srcChars,
    const char  srcData[],
    unsigned    dstChars,
    byte *      dstData
) {
    ASSERT(srcData);
    ASSERT(dstChars >= Base64DecodeSize(srcChars));
    ASSERT(dstData);
    ref(dstChars);

    const byte * dstBase = dstData;
    const char * srcTerm = srcData + srcChars;
    while (srcTerm - srcData >= 4) {

        *dstData++ = (byte) (
            (kDecode64[srcData[0]] << 2 & 0xfc)
           +(kDecode64[srcData[1]] >> 4 & 0x03)
        );

        if (kDecode64[srcData[2]] == kTerminator)
            break;

        *dstData++ = (byte) (
            (kDecode64[srcData[1]] << 4 & 0xf0)
           +(kDecode64[srcData[2]] >> 2 & 0x0f)
        );

        if (kDecode64[srcData[3]] == kTerminator)
            break;

        *dstData++ = (byte) (
            (kDecode64[srcData[2]] << 6 & 0xc0)
           +(kDecode64[srcData[3]])
        );

        srcData += 4;
    }

    return dstData - dstBase;
}