Alexander "PapaTutuWawa
438012d8f8
It seems that the varint encoding function would not work for some integers as input. This should in theory fix this issue. Since the SPK IDs are randomly between 0 and 2**32 - 1, it makes sense that the tests fail only sometimes.
66 lines
1.6 KiB
Dart
66 lines
1.6 KiB
Dart
/// Masks the 7 LSB
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const lsb7Mask = 0x7F;
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/// Constant for setting the MSB
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const msb = 1 << 7;
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/// Field types
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const fieldTypeUint32 = 0;
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const fieldTypeByteArray = 2;
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int fieldId(int number, int type) {
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return (number << 3) | type;
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}
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class VarintDecode {
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const VarintDecode(this.n, this.length);
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final int n;
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final int length;
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}
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/// Decode a Varint that begins at [input]'s index [offset].
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VarintDecode decodeVarint(List<int> input, int offset) {
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// The return value
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var n = 0;
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// The byte offset counter
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var i = 0;
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// Iterate until the MSB of the byte is 0
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while (true) {
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// Mask only the 7 LSB and "move" them accordingly
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n += (input[offset + i] & lsb7Mask) << (7 * i);
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// Break if we reached the end
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if (input[offset + i] & 1 << 7 == 0) {
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break;
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}
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i++;
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}
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return VarintDecode(n, i + 1);
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}
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// Encodes the integer [i] into a Varint.
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List<int> encodeVarint(int i) {
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assert(i >= 0, "Two's complement is not implemented");
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final ret = List<int>.empty(growable: true);
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// Thanks to https://github.com/hathibelagal-dev/LEB128 for the trick with toRadixString!
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final numSevenBlocks = (i.toRadixString(2).length / 7).ceil();
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for (var j = 0; j < numSevenBlocks; j++) {
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// The 7 LSB of the byte we're creating
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final x = (i & (lsb7Mask << j * 7)) >> j * 7;
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if (j == numSevenBlocks - 1) {
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// If we were to shift further, we only get zero, so we're at the end
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ret.add(x);
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} else {
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// We still have at least one bit more to go, so set the MSB to 1
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ret.add(x + msb);
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}
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}
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return ret;
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}
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