base64编解码的另外几个版本

#include "crypto/encode/base64.h"

static const std::string base64_chars =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "abcdefghijklmnopqrstuvwxyz"
    "0123456789+/";

static inline bool is_base64(unsigned char c)
{
    return (isalnum(c) || (c == '+') || (c == '/'));
}

std::string Base64::Encode(const std::string& src)
{
    std::string ret;
    unsigned char char_array_3[];
    unsigned char char_array_4[];

    size_t srcLen = src.length();
    const char* pSrc = src.c_str();

    size_t i = ;
    while (srcLen--) {
        char_array_3[i++] = *(pSrc++);
        if (i == ) {
            char_array_4[] = (char_array_3[] & 0xfc) >> ;
            char_array_4[] = ((char_array_3[] & 0x03) << ) + ((char_array_3[] & 0xf0) >> );
            char_array_4[] = ((char_array_3[] & 0x0f) << ) + ((char_array_3[] & 0xc0) >> );
            char_array_4[] = char_array_3[] & 0x3f;

            for (i = ; (i <); i++)
                ret += base64_chars[char_array_4[i]];
            i = ;
        }
    }

    size_t j = ;
    if (i)
    {
        for (j = i; j < ; j++)
            char_array_3[j] = '\0';

        char_array_4[] = (char_array_3[] & 0xfc) >> ;
        char_array_4[] = ((char_array_3[] & 0x03) << ) + ((char_array_3[] & 0xf0) >> );
        char_array_4[] = ((char_array_3[] & 0x0f) << ) + ((char_array_3[] & 0xc0) >> );
        char_array_4[] = char_array_3[] & 0x3f;

        for (j = ; (j < i + ); j++)
            ret += base64_chars[char_array_4[j]];

        while ((i++ < ))
            ret += '=';

    }

    return ret;
}

std::string Base64::Encode(const unsigned char* src, size_t dataLen)
{
    if ((src == NULL) || (dataLen == ))
    {
        return std::string();
    }

    std::string ret;
    unsigned char char_array_3[];
    unsigned char char_array_4[];

    size_t srcLen = dataLen;
    const char* pSrc = reinterpret_cast<const char*>(src);

    size_t i = ;
    while (srcLen--) {
        char_array_3[i++] = *(pSrc++);
        if (i == ) {
            char_array_4[] = (char_array_3[] & 0xfc) >> ;
            char_array_4[] = ((char_array_3[] & 0x03) << ) + ((char_array_3[] & 0xf0) >> );
            char_array_4[] = ((char_array_3[] & 0x0f) << ) + ((char_array_3[] & 0xc0) >> );
            char_array_4[] = char_array_3[] & 0x3f;

            for (i = ; (i <); i++)
                ret += base64_chars[char_array_4[i]];
            i = ;
        }
    }

    size_t j = ;
    if (i)
    {
        for (j = i; j < ; j++)
            char_array_3[j] = '\0';

        char_array_4[] = (char_array_3[] & 0xfc) >> ;
        char_array_4[] = ((char_array_3[] & 0x03) << ) + ((char_array_3[] & 0xf0) >> );
        char_array_4[] = ((char_array_3[] & 0x0f) << ) + ((char_array_3[] & 0xc0) >> );
        char_array_4[] = char_array_3[] & 0x3f;

        for (j = ; (j < i + ); j++)
            ret += base64_chars[char_array_4[j]];

        while ((i++ < ))
            ret += '=';
    }

    return ret;
}

bool Base64::Decode(const std::string& src, std::string& out)
{
    out.clear();

    size_t in_len = src.size();
    size_t i = ;
    size_t j = ;
    size_t in_ = ;
    unsigned char char_array_4[], char_array_3[];

    while (in_len-- && (src[in_] != '=') && is_base64(src[in_])) {
        char_array_4[i++] = src[in_]; in_++;
        if (i == ) {
            for (i = ; i <; i++)
                char_array_4[i] = (unsigned char)base64_chars.find(char_array_4[i]);

            char_array_3[] = (char_array_4[] << ) + ((char_array_4[] & 0x30) >> );
            char_array_3[] = ((char_array_4[] & 0xf) << ) + ((char_array_4[] & 0x3c) >> );
            char_array_3[] = ((char_array_4[] & 0x3) << ) + char_array_4[];

            for (i = ; (i < ); i++)
                out += char_array_3[i];
            i = ;
        }
    }

    if (i) {
        for (j = i; j <; j++)
            char_array_4[j] = ;

        for (j = ; j <; j++)
            char_array_4[j] = (unsigned char)base64_chars.find(char_array_4[j]);

        char_array_3[] = (char_array_4[] << ) + ((char_array_4[] & 0x30) >> );
        char_array_3[] = ((char_array_4[] & 0xf) << ) + ((char_array_4[] & 0x3c) >> );
        char_array_3[] = ((char_array_4[] & 0x3) << ) + char_array_4[];

        for (j = ; (j < i - ); j++)
            out += char_array_3[j];
    }

    return true;
}

bool Base64::Decode(const unsigned char* src, size_t srcLen, unsigned char* decoded, size_t& decoded_length)
{
    if ((src == NULL) || (srcLen < ))
        return false;
    if ((decoded == NULL) || (decoded_length < ))
        return false;

    size_t i = ;
    size_t j = ;
    size_t in_ = ;
    unsigned char char_array_4[];
    unsigned char char_array_3[];

    size_t offset = ;
    while (srcLen-- && (src[in_] != '=') && is_base64(src[in_])) {
        char_array_4[i++] = src[in_]; in_++;
        if (i == ) {
            for (i = ; i <; i++)
                char_array_4[i] = (unsigned char)base64_chars.find(char_array_4[i]);

            char_array_3[] = (char_array_4[] << ) + ((char_array_4[] & 0x30) >> );
            char_array_3[] = ((char_array_4[] & 0xf) << ) + ((char_array_4[] & 0x3c) >> );
            char_array_3[] = ((char_array_4[] & 0x3) << ) + char_array_4[];

            for (i = ; i < ; i++)
            {
                if (offset < decoded_length)
                    decoded[offset++] = char_array_3[i];
                else
                    return false;
            }
            i = ;
        }
    }

    if (i) {
        for (j = i; j <; j++)
            char_array_4[j] = ;

        for (j = ; j <; j++)
            char_array_4[j] = (unsigned char)base64_chars.find(char_array_4[j]);

        char_array_3[] = (char_array_4[] << ) + ((char_array_4[] & 0x30) >> );
        char_array_3[] = ((char_array_4[] & 0xf) << ) + ((char_array_4[] & 0x3c) >> );
        char_array_3[] = ((char_array_4[] & 0x3) << ) + char_array_4[];

        for (j = ; (j < i - ); j++)
        {
            if (offset < decoded_length)
                decoded[offset++] = char_array_3[j];
            else
                return false;
        }
    }

    decoded_length = offset;

    return true;
}

bool Base64::Decode(const unsigned char* src, size_t srcLen, std::vector<unsigned char>& out)
{
    out.clear();

    size_t i = ;
    size_t j = ;
    size_t in_ = ;
    unsigned char char_array_4[];
    unsigned char char_array_3[];

    while (srcLen-- && (src[in_] != '=') && is_base64(src[in_])) {
        char_array_4[i++] = src[in_]; in_++;
        if (i == ) {
            for (i = ; i <; i++)
                char_array_4[i] = (unsigned char)base64_chars.find(char_array_4[i]);

            char_array_3[] = (char_array_4[] << ) + ((char_array_4[] & 0x30) >> );
            char_array_3[] = ((char_array_4[] & 0xf) << ) + ((char_array_4[] & 0x3c) >> );
            char_array_3[] = ((char_array_4[] & 0x3) << ) + char_array_4[];

            for (i = ; (i < ); i++)
                out.push_back(char_array_3[i]);
            i = ;
        }
    }

    if (i) {
        for (j = i; j <; j++)
            char_array_4[j] = ;

        for (j = ; j <; j++)
            char_array_4[j] = (unsigned char)base64_chars.find(char_array_4[j]);

        char_array_3[] = (char_array_4[] << ) + ((char_array_4[] & 0x30) >> );
        char_array_3[] = ((char_array_4[] & 0xf) << ) + ((char_array_4[] & 0x3c) >> );
        char_array_3[] = ((char_array_4[] & 0x3) << ) + char_array_4[];

        for (j = ; (j < i - ); j++)
            out.push_back(char_array_3[j]);
    }

    return true;
}