c# - BinaryWriterWith7BitEncoding & BinaryReaderWith7BitEncoding

Question

先生。 Ayende 在他的 latest blog post about an implementation of a queue 中写道.在帖子中，他使用了两个神奇的文件:BinaryWriterWith7BitEncoding 和 BinaryReaderWith7BitEncoding

BinaryWriterWith7BitEncoding int和long都可以写吗？使用以下方法签名:void WriteBitEncodedNullableInt64(long? value) & void Write7BitEncodedInt(int value)

和

BinaryReaderWith7BitEncoding 可以读取使用以下方法签名写入的值:long? ReadBitEncodedNullableInt64() 和 int Read7BitEncodedInt()

到目前为止，我只找到了一种读取 7BitEncodedInt 的方法:

protected int Read7BitEncodedInt()
{
    int value = 0;
    int byteval;
    int shift = 0;
    while(((byteval = ReadByte()) & 0x80) != 0)
    {
        value |= ((byteval & 0x7F) << shift);
        shift += 7;
    }
    return (value | (byteval << shift));
}

我不太擅长字节移位 - 有人知道如何读写 7BitEncoded long 吗？并写入 int ?

Answer 1

下面是这样的写法:

    static void Write7BitEncodedInt32(Stream dest, int value)
    {
        Write7BitEncodedUInt32(dest, (uint) value);
    }
    static void Write7BitEncodedUInt32(Stream dest, uint value)
    {
        if(value < 128) { dest.WriteByte((byte)value); return;}
        while(value != 0)
        {
            byte b = (byte) (value & 0x7F);
            value >>= 7; // since uint, we'll eventually run out of 1s
            if (value != 0) b |= 0x80; // and there's more
            dest.WriteByte(b);
        }
    }