#include "BaseEncoding.h"

Static Public Member Functions
static constexpr std::size_t	EncodedSize (std::size_t size)

static constexpr std::size_t	DecodedSize (std::size_t size)

static std::string	Encode (std::vector< uint8 > const &data)

static Optional< std::vector< uint8 > >	Decode (std::string const &data)

Static Public Attributes
static constexpr std::size_t	BITS_PER_CHAR = Encoding::BITS_PER_CHAR

static constexpr std::size_t	PAD_TO = std::lcm(8u, BITS_PER_CHAR)

static constexpr uint8	DECODE_ERROR = Encoding::DECODE_ERROR

static constexpr char	PADDING = Encoding::PADDING

Detailed Description

template<typename Encoding>
struct Acore::Impl::GenericBaseEncoding< Encoding >

Member Function Documentation

◆ Decode()

template<typename Encoding >

static Optional< std::vector< uint8 > > Acore::Impl::GenericBaseEncoding< Encoding >::Decode ( std::string const & data )

inlinestatic

        {
            auto it = data.begin(), end = data.end();
            if (it == end)
            {
                return std::vector<uint8>();
            }
 
            std::vector<uint8> v;
            v.reserve(DecodedSize(data.size()));
 
            uint8 currentByte = 0;
            uint8 bitsLeft = 8; // in current byte
            while ((it != end) && (*it != PADDING))
            {
                uint8 cur = Encoding::Decode(*(it++));
                if (cur == DECODE_ERROR)
                    return {};
 
                if (bitsLeft > BITS_PER_CHAR)
                {
                    bitsLeft -= BITS_PER_CHAR;
                    currentByte |= (cur << bitsLeft);
                }
                else
                {
                    bitsLeft = BITS_PER_CHAR - bitsLeft; // in encoded char
                    currentByte |= (cur >> bitsLeft);
                    v.push_back(currentByte);
                    currentByte = (cur & ((1 << bitsLeft) - 1));
                    bitsLeft = 8 - bitsLeft; // in byte again
                    currentByte <<= bitsLeft;
                }
            }
 
            if (currentByte)
                return {}; // decode error, trailing non-zero bits
 
            // process padding
            while ((it != end) && (*it == PADDING) && (bitsLeft != 8))
            {
                if (bitsLeft > BITS_PER_CHAR)
                {
                    bitsLeft -= BITS_PER_CHAR;
                }
                else
                {
                    bitsLeft += (8 - BITS_PER_CHAR);
                }
                ++it;
            }
 
            // ok, all padding should be consumed, and we should be at end of string
            if (it == end)
            {
                return v;
            }
 
            // anything else is an error
            return {};
        }

References Acore::Impl::GenericBaseEncoding< Encoding >::BITS_PER_CHAR, Acore::Impl::GenericBaseEncoding< Encoding >::DECODE_ERROR, Acore::Impl::GenericBaseEncoding< Encoding >::DecodedSize(), and Acore::Impl::GenericBaseEncoding< Encoding >::PADDING.

Referenced by Acore::Encoding::Base32::Decode(), and Acore::Encoding::Base64::Decode().

◆ DecodedSize()

template<typename Encoding >

static constexpr std::size_t Acore::Impl::GenericBaseEncoding< Encoding >::DecodedSize ( std::size_t size )

inlinestaticconstexpr

        {
            size *= BITS_PER_CHAR; // bits in input
            if (size % PAD_TO) // pad to boundary
            {
                size += (PAD_TO - (size % PAD_TO));
            }
            return (size / 8);
        }

References Acore::Impl::GenericBaseEncoding< Encoding >::BITS_PER_CHAR, and Acore::Impl::GenericBaseEncoding< Encoding >::PAD_TO.

Referenced by Acore::Impl::GenericBaseEncoding< Encoding >::Decode().

◆ Encode()

template<typename Encoding >

static std::string Acore::Impl::GenericBaseEncoding< Encoding >::Encode ( std::vector< uint8 > const & data )

inlinestatic

        {
            auto it = data.begin(), end = data.end();
            if (it == end)
            {
                return "";
            }
 
            std::string s;
            s.reserve(EncodedSize(data.size()));
 
            uint8 bitsLeft = 8; // in current byte
            do
            {
                uint8 thisC = 0;
                if (bitsLeft >= BITS_PER_CHAR)
                {
                    bitsLeft -= BITS_PER_CHAR;
                    thisC = ((*it >> bitsLeft) & ((1 << BITS_PER_CHAR) - 1));
                    if (!bitsLeft)
                    {
                        ++it;
                        bitsLeft = 8;
                    }
                }
                else
                {
                    thisC = (*it & ((1 << bitsLeft) - 1)) << (BITS_PER_CHAR - bitsLeft);
                    bitsLeft += (8 - BITS_PER_CHAR);
                    if ((++it) != end)
                    {
                        thisC |= (*it >> bitsLeft);
                    }
                }
                s.append(1, Encoding::Encode(thisC));
            } while (it != end);
 
            while (bitsLeft != 8)
            {
                if (bitsLeft > BITS_PER_CHAR)
                {
                    bitsLeft -= BITS_PER_CHAR;
                }
                else
                {
                    bitsLeft += (8 - BITS_PER_CHAR);
                }
                s.append(1, PADDING);
            }
 
            return s;
        }

References Acore::Impl::GenericBaseEncoding< Encoding >::BITS_PER_CHAR, Acore::Impl::GenericBaseEncoding< Encoding >::EncodedSize(), and Acore::Impl::GenericBaseEncoding< Encoding >::PADDING.

Referenced by Acore::Encoding::Base32::Encode(), and Acore::Encoding::Base64::Encode().

◆ EncodedSize()

template<typename Encoding >

static constexpr std::size_t Acore::Impl::GenericBaseEncoding< Encoding >::EncodedSize ( std::size_t size )

inlinestaticconstexpr

        {
            size *= 8; // bits in input
            if (size % PAD_TO) // pad to boundary
            {
                size += (PAD_TO - (size % PAD_TO));
            }
            return (size / BITS_PER_CHAR);
        }