Himi的base64代码

Himi的base64代码

//

//  DataHimi.cpp

//  Oh!MonsterMR

//

//  Created by Himi on 12-3-8.

//  Copyright (c) 2012年 Augustimpression. All rights reserved.

//

#include "DataBase64Himi.h"

static const std::string dataChars =

"ABCDEFGHIJKLMNOPQRSTUVWXYZ"

"abcdefghijklmnopqrstuvwxyz"

"0123456789+/";

static inline bool baseData(unsigned char c) {

    return (isalnum(c) || (c == '+') || (c == '/'));

}

std::string himiSaveData(unsigned char const* bytes_to_encode, unsigned int in_len) {

    std::string ret;

    int i = 0;

    int j = 0;

    unsigned char char_array_3[3];

    unsigned char char_array_4[4];

    while (in_len--) {

        char_array_3[i++] = *(bytes_to_encode++);

        if (i == 3) {

            char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;

            char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);

            char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);

            char_array_4[3] = char_array_3[2] & 0x3f;

            for(i = 0; (i <4) ; i++)

                ret += dataChars[char_array_4[i]];

            i = 0;

        }

    }

    if (i)

    {

        for(j = i; j < 3; j++)

            char_array_3[j] = '\0';

        char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;

        char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);

        char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);

        char_array_4[3] = char_array_3[2] & 0x3f;

        for (j = 0; (j < i + 1); j++)

            ret += dataChars[char_array_4[j]];

        while((i++ < 3))

            ret += '=';

    }

    return ret;

}

std::string himiParseData(std::string const& encoded_string) {

    int in_len = encoded_string.size();

    int i = 0;

    int j = 0;

    int in_ = 0;

    unsigned char char_array_4[4], char_array_3[3];

    std::string ret;

    while (in_len-- && ( encoded_string[in_] != '=') && baseData(encoded_string[in_])) {

        char_array_4[i++] = encoded_string[in_]; in_++;

        if (i ==4) {

            for (i = 0; i <4; i++)

                char_array_4[i] = dataChars.find(char_array_4[i]);

            char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);

            char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);

            char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];

            for (i = 0; (i < 3); i++)

                ret += char_array_3[i];

            i = 0;

        }

    }

    if (i) {

        for (j = i; j <4; j++)

            char_array_4[j] = 0;

        for (j = 0; j <4; j++)

            char_array_4[j] = dataChars.find(char_array_4[j]);

        char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);

        char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);

        char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];

        for (j = 0; (j < i - 1); j++) ret += char_array_3[j];

    }

    return ret;

}