assimp/code/AssetLib/FBX/FBXUtil.cpp

/*
Open Asset Import Library (assimp)
----------------------------------------------------------------------

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  copyright notice, this list of conditions and the
  following disclaimer.

* Redistributions in binary form must reproduce the above
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

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*/

/** @file  FBXUtil.cpp
 *  @brief Implementation of internal FBX utility functions
 */

#include "FBXUtil.h"
#include "FBXTokenizer.h"

#include <assimp/TinyFormatter.h>
#include <string>
#include <cstring>

#ifndef ASSIMP_BUILD_NO_FBX_IMPORTER

namespace Assimp {
namespace FBX {
namespace Util {

// ------------------------------------------------------------------------------------------------
const char* TokenTypeString(TokenType t)
{
    switch(t) {
        case TokenType_OPEN_BRACKET:
            return "TOK_OPEN_BRACKET";

        case TokenType_CLOSE_BRACKET:
            return "TOK_CLOSE_BRACKET";

        case TokenType_DATA:
            return "TOK_DATA";

        case TokenType_COMMA:
            return "TOK_COMMA";

        case TokenType_KEY:
            return "TOK_KEY";

        case TokenType_BINARY_DATA:
            return "TOK_BINARY_DATA";
    }

    ai_assert(false);
    return "";
}


// ------------------------------------------------------------------------------------------------
std::string GetOffsetText(size_t offset)
{
    return static_cast<std::string>( Formatter::format() << " (offset 0x" << std::hex << offset << ") " );
}

// ------------------------------------------------------------------------------------------------
std::string GetLineAndColumnText(unsigned int line, unsigned int column)
{
    return static_cast<std::string>( Formatter::format() << " (line " << line << " <<  col " << column << ") " );
}

// ------------------------------------------------------------------------------------------------
std::string GetTokenText(const Token* tok)
{
    if(tok->IsBinary()) {
        return static_cast<std::string>( Formatter::format() <<
            " (" << TokenTypeString(tok->Type()) <<
            ", offset 0x" << std::hex << tok->Offset() << ") " );
    }

    return static_cast<std::string>( Formatter::format() <<
        " (" << TokenTypeString(tok->Type()) <<
        ", line " << tok->Line() <<
        ", col " << tok->Column() << ") " );
}

// Generated by this formula: T["ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"[i]] = i;
static const uint8_t base64DecodeTable[128] = {
    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 62, 255, 255, 255, 63,
    52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 255, 255, 255, 255, 255, 255,
    255, 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, 255, 255, 255, 255, 255,
    255, 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, 255, 255, 255, 255, 255
};

uint8_t DecodeBase64(char ch)
{
    const auto idx = static_cast<uint8_t>(ch);
    if (idx > 127)
        return 255;
    return base64DecodeTable[idx];
}

size_t ComputeDecodedSizeBase64(const char* in, size_t inLength)
{
    if (inLength < 2)
    {
        return 0;
    }
    const size_t equals = size_t(in[inLength - 1] == '=') + size_t(in[inLength - 2] == '=');
    const size_t full_length = (inLength * 3) >> 2; // div by 4
    if (full_length < equals)
    {
        return 0;
    }
    return full_length - equals;
}

size_t DecodeBase64(const char* in, size_t inLength, uint8_t* out, size_t maxOutLength)
{
    if (maxOutLength == 0 || inLength < 2) {
        return 0;
    }
    const size_t realLength = inLength - size_t(in[inLength - 1] == '=') - size_t(in[inLength - 2] == '=');
    size_t dst_offset = 0;
    int val = 0, valb = -8;
    for (size_t src_offset = 0; src_offset < realLength && dst_offset < maxOutLength; ++src_offset)
    {
        const uint8_t table_value = Util::DecodeBase64(in[src_offset]);
        if (table_value == 255)
        {
            return 0;
        }
        val = (val << 6) + table_value;
        valb += 6;
        if (valb >= 0)
        {
            out[dst_offset++] = static_cast<uint8_t>((val >> valb) & 0xFF);
            valb -= 8;
            val &= 0xFFF;
        }
    }
    return dst_offset;
}

static const char to_base64_string[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
char EncodeBase64(char byte)
{
    return to_base64_string[(size_t)byte];
}

/** Encodes a block of 4 bytes to base64 encoding
*
*  @param bytes Bytes to encode.
*  @param out_string String to write encoded values to.
*  @param string_pos Position in out_string.*/
void EncodeByteBlock(const char* bytes, std::string& out_string, size_t string_pos)
{
    char b0 = (bytes[0] & 0xFC) >> 2;
    char b1 = (bytes[0] & 0x03) << 4 | ((bytes[1] & 0xF0) >> 4);
    char b2 = (bytes[1] & 0x0F) << 2 | ((bytes[2] & 0xC0) >> 6);
    char b3 = (bytes[2] & 0x3F);

    out_string[string_pos + 0] = EncodeBase64(b0);
    out_string[string_pos + 1] = EncodeBase64(b1);
    out_string[string_pos + 2] = EncodeBase64(b2);
    out_string[string_pos + 3] = EncodeBase64(b3);
}

std::string EncodeBase64(const char* data, size_t length)
{
    // calculate extra bytes needed to get a multiple of 3
    size_t extraBytes = 3 - length % 3;

    // number of base64 bytes
    size_t encodedBytes = 4 * (length + extraBytes) / 3;

    std::string encoded_string(encodedBytes, '=');

    // read blocks of 3 bytes
    for (size_t ib3 = 0; ib3 < length / 3; ib3++)
    {
        const size_t iByte = ib3 * 3;
        const size_t iEncodedByte = ib3 * 4;
        const char* currData = &data[iByte];

        EncodeByteBlock(currData, encoded_string, iEncodedByte);
    }

    // if size of data is not a multiple of 3, also encode the final bytes (and add zeros where needed)
    if (extraBytes > 0)
    {
        char finalBytes[4] = { 0,0,0,0 };
        memcpy(&finalBytes[0], &data[length - length % 3], length % 3);

        const size_t iEncodedByte = encodedBytes - 4;
        EncodeByteBlock(&finalBytes[0], encoded_string, iEncodedByte);

        // add '=' at the end
        for (size_t i = 0; i < 4 * extraBytes / 3; i++)
            encoded_string[encodedBytes - i - 1] = '=';
    }
    return encoded_string;
}

} // !Util
} // !FBX
} // !Assimp

#endif