Ruby convert 64 bit IEEE 754 hexadecimal to double

Question

I need to output a hex data stream from an IMU into lat long and height values.

The data comes in as double precision hex strings and I need to output them into decimal values.

I tried several pack and unpack values but in the end wasn't able to find a solution except that of writing my own function.

Is there any way of translating this double precision 64bit hex string:

"4044F33333333333"

into this decimal:

41.900000000000000

Using pack and unpack functions?

Are there any libraries able to deal with IEEE 754 numbers?

Answer 1

["4044F33333333333"].pack('H16').unpack('G').first
=> 41.9

# broken down to steps, showing reversability
["4044F33333333333"].pack('H16')
=> "@D\xF333333"
"@D\xF333333".unpack('G')
=> [41.9]
[41.9].pack('G')
=> "@D\xF333333"
"@D\xF333333".unpack('H16')
=> ["4044f33333333333"]