VB.NET bit shift confusion

Question

I have some questions regarding VB.NET bit shifting. I understand the << >> operators are bit shift operators in VB.NET.

I have a two-byte hex value, 0x3ACC, and each bit in these two bytes represents either a day, month or year. The bit structure of this hex value is yyyy yyym mmmd dddd.

I am confused as to how I should bit shift these values so that year, month and day are in their own UINT16 values. What should the shifting numbers be and do I need to add any padding to the shift?

Answer 1

You're going to need to use And as well as the bit shifting operations to get your result. You need to shift right (count the "non-year" bits for the amount) to get just the year. To get the day, just And with the value that has all the "day" bits set. Extracting the month will require a combination of the two techniques, either Anding then >> or >> and then Anding with the correct mask.

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Spoilers:

• To extract the year: 0x3ACC >> 9
• To extract the day: 0x3ACC And 0x001F
• To extract the month: 0x3ACC And 0x01E0 >> 5