Function Base64Encode

src/StringUtils.cpp:782–824

AString Base64Encode(const AString & a_Input)
{
	static const char BASE64[64] = {
		'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P',
		'Q','R','S','T','U','V','W','X','Y','Z','a','b','c','d','e','f',
		'g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v',
		'w','x','y','z','0','1','2','3','4','5','6','7','8','9','+','/'
	};

	AString output;
	output.resize(((a_Input.size() + 2) / 3) * 4);

	size_t output_index = 0;
	size_t size_full24 = (a_Input.size() / 3) * 3;

	for (size_t i = 0; i < size_full24; i += 3)
	{
		output[output_index++] = BASE64[(unsigned char)a_Input[i] >> 2];
		output[output_index++] = BASE64[((unsigned char)a_Input[i] << 4 | (unsigned char)a_Input[i + 1] >> 4) & 63];
		output[output_index++] = BASE64[((unsigned char)a_Input[i + 1] << 2 | (unsigned char)a_Input[i + 2] >> 6) & 63];
		output[output_index++] = BASE64[(unsigned char)a_Input[i + 2] & 63];
	}

	if (size_full24 < a_Input.size())
	{
		output[output_index++] = BASE64[(unsigned char)a_Input[size_full24] >> 2];
		if (size_full24 + 1 == a_Input.size())
		{
			output[output_index++] = BASE64[((unsigned char)a_Input[size_full24] << 4) & 63];
			output[output_index++] = '=';
		}
		else
		{
			output[output_index++] = BASE64[((unsigned char)a_Input[size_full24] << 4 | (unsigned char)a_Input[size_full24 + 1] >> 4) & 63];
			output[output_index++] = BASE64[((unsigned char)a_Input[size_full24 + 1] << 2) & 63];
		}

		output[output_index++] = '=';
	}
	ASSERT(output_index == output.size());

	return output;
}