HexDump.cc

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#include "HexDump.hh"
#include "narrow.hh"
#include "strCat.hh"
#include "xrange.hh"
#include <algorithm>
#include <cassert>
 
namespace HexDump {
 
using openmsx::MemBuffer;
 
[[nodiscard]] static constexpr char encode2(uint8_t x)
{
        return (x < 10) ? char(x + '0') : char(x - 10 + 'A');
}
[[nodiscard]] static auto encode(uint8_t x)
{
        return tmpStrCat(encode2(x >> 4), encode2(x & 15));
}
std::string encode(std::span<const uint8_t> input, bool newlines)
{
        std::string ret;
        size_t in = 0;
        auto len = input.size();
        while (len) {
                if (newlines && !ret.empty()) ret += '\n';
                auto t = int(std::min<size_t>(16, len));
                for (auto i : xrange(t)) {
                        ret += encode(input[in++]);
                        if (i != (t - 1)) ret += ' ';
                }
                len -= t;
        }
        return ret;
}
 
[[nodiscard]] static constexpr int decode(char x)
{
        if (('0' <= x) && (x <= '9')) {
                return x - '0';
        } else if (('A' <= x) && (x <= 'F')) {
                return x - 'A' + 10;
        } else if (('a' <= x) && (x <= 'f')) {
                return x - 'a' + 10;
        } else {
                return -1;
        }
}
std::pair<MemBuffer<uint8_t>, size_t> decode(std::string_view input)
{
        auto inSize = input.size();
        auto outSize = inSize / 2; // overestimation
        MemBuffer<uint8_t> ret(outSize); // too big
 
        size_t out = 0;
        bool flip = true;
        uint8_t tmp = 0;
        for (char c : input) {
                int d = decode(c);
                if (d == -1) continue;
                assert(d >= 0);
                assert(d <= 15);
                if (flip) {
                        tmp = narrow<uint8_t>(d);
                } else {
                        ret[out++] = narrow<uint8_t>((tmp << 4) | d);
                }
                flip = !flip;
        }
 
        assert(outSize >= out);
        ret.resize(out); // shrink to correct size
        return {std::move(ret), out};
}
 
bool decode_inplace(std::string_view input, std::span<uint8_t> output)
{
        size_t out = 0;
        auto outSize = output.size();
        bool flip = true;
        uint8_t tmp = 0;
        for (char c : input) {
                int d = decode(c);
                if (d == -1) continue;
                assert(d >= 0);
                assert(d <= 15);
                if (flip) {
                        tmp = narrow<uint8_t>(d);
                } else {
                        if (out == outSize) [[unlikely]] return false;
                        output[out++] = narrow<uint8_t>((tmp << 4) | d);
                }
                flip = !flip;
        }
 
        return out == outSize;
}
 
} // namespace HexDump