--- a/src/types/IntegerDataTypeReader.h Tue Dec 03 16:30:02 2019 +0100
+++ b/src/types/IntegerDataTypeReader.h Tue Dec 10 19:37:50 2019 +0100
@@ -38,61 +38,16 @@
using namespace relpipe::reader;
/**
- * The prototype does not have various integer and other numeric data types,
- * it just works with one type of integer.
- * But this integer has variable length -- smaller values occupy only one byte, bigger ones, more bytes 1,2,4,8 + first byte (contains length signalization).
- * In the real implementation of relational pipes, there will be DataTypes for particular numeric types.
- *
- * TODO: support also big endian architectures.
- * TODO: throw exception if a value was stored in bigger type than needed (while reading – there should be only one supported way how to encode a single value)
- *
- * Example of encoded values:
- * -------------------------------------------------------------------------------------------------
- * $ for n in 0 1 10 250 251 252 65535 65536 4294967295 4294967296 18446744073709551615; do printf '%20s = ' $n; dist/Debug/GNU-Linux/rp-prototype write integer $n | hd | head -n 1; done
- * 0 = 00000000 00 |.|
- * 1 = 00000000 01 |.|
- * 10 = 00000000 0a |.|
- * 250 = 00000000 fa |.|
- * 251 = 00000000 fb fb |..|
- * 252 = 00000000 fb fc |..|
- * 65535 = 00000000 fc ff ff |...|
- * 65536 = 00000000 fd 00 00 01 00 |.....|
- * 4294967295 = 00000000 fd ff ff ff ff |.....|
- * 4294967296 = 00000000 fe 00 00 00 00 01 00 00 00 |.........|
- * 18446744073709551615 = 00000000 fe ff ff ff ff ff ff ff ff |.........|
- * -------------------------------------------------------------------------------------------------
- *
- * Example of decoded values:
- * -------------------------------------------------------------------------------------------------
- * $ for n in 0 1 10 250 251 252 65535 65536 4294967295 4294967296 18446744073709551615; do dist/Debug/GNU-Linux/rp-prototype write integer $n | dist/Debug/GNU-Linux/rp-prototype read integer; done;
- * 0
- * 1
- * 10
- * 250
- * 251
- * 252
- * 65535
- * 65536
- * 4294967295
- * 4294967296
- * 18446744073709551615
- * -------------------------------------------------------------------------------------------------
- *
- * Note: similar format as original idea: https://en.wikipedia.org/wiki/X.690#Length_octets
- *
+ * Unsigned variable-length integer.
+ * ULEB128
*/
class IntegerDataTypeReader : public DataTypeReader<integer_t> {
private:
- static const uint8_t INTEGER_TYPE_UINT8 = 251;
- static const uint8_t INTEGER_TYPE_UINT16 = 252;
- static const uint8_t INTEGER_TYPE_UINT32 = 253;
- static const uint8_t INTEGER_TYPE_UINT64 = 254;
- static const uint8_t INTEGER_TYPE_RESERVED = 255;
- template<typename T> integer_t read(std::istream &input) {
- T value = 0;
- input.read(reinterpret_cast<char *> (&value), sizeof (value));
- return value;
+ uint8_t readNextOctet(std::istream &input) {
+ uint8_t value = input.get();
+ if (input.good()) return value;
+ else throw RelpipeReaderException(L"Unable to read next octet of the integer.");
}
public:
@@ -101,19 +56,15 @@
}
integer_t readValue(std::istream &input) override {
- uint8_t first;
- input.read(reinterpret_cast<char *> (&first), sizeof (first));
- if (input.good()) {
-
- if (first < INTEGER_TYPE_UINT8) return first;
- else if (first == INTEGER_TYPE_UINT8) return read<uint8_t>(input);
- else if (first == INTEGER_TYPE_UINT16) return read<uint16_t>(input);
- else if (first == INTEGER_TYPE_UINT32) return read<uint32_t>(input);
- else if (first == INTEGER_TYPE_UINT64) return read<uint64_t>(input);
- else throw RelpipeReaderException(L"Error while parsing integer type: unsupported type");
- } else {
- throw RelpipeReaderException(L"Error while reading integer from the stream.");
- }
+ integer_t value = 0;
+ integer_t shift = 0;
+ octet_t octet;
+ do {
+ octet = readNextOctet(input);
+ value += integer_t(octet & 0x7F) << shift;
+ shift += 7;
+ } while (octet >= 128);
+ return value;
}
string_t toString(const integer_t &value) override {
@@ -124,4 +75,4 @@
}
}
-}
\ No newline at end of file
+}