Yeah, BrowserUk was adding that last bit while I was too hastily replying to his very helpful post.

I understand the bitmask and the right-shift operations much better now. This example had the concreteness and immediacy I needed. It helps me a lot to display the bitmask AND operation in binary.

my $day   = ( $short_int & 0b0000000_0000_11111 )      ;
my $month = ( $short_int & 0b0000000_1111_00000 ) >> 5 ;
my $year  = ( $short_int & 0b1111111_0000_00000 ) >> 9 ;

my $date  = sprintf "%04d-%02d-%02d", 1980 + $year, $month, $day;

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Is there any reason not to use these binary constants instead of hexadecimal constants in the real program?

I suppose in a real program, the binary/hexadecimal constants and the year 1980 would be symbolic constants; e.g., DAY_MASK and EPOCH_YEAR. Or not.

In reply to Re^4: Practical Example of Converting Packed Value by Jim
in thread Practical Example of Converting Packed Value by Jim

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