blob.swap2()
Changes the order of the blob’s bytes
Availability
Device + Agent
Returns
Nothing
Description
This method changes the order of the contents of the target blob by reversing the order of every two bytes: bytes 0 and 1 become bytes 1 and 0, bytes 2 and 3 become bytes 3 and 2, and so on:
If each pair of bytes forms a 16-bit integer value, swap2() allows you change the ‘endian’ nature of this value: ie. whether its most-significant byte comes first or last. The imp is little-endian, but not all devices are, and this method allows you to interpret readings from them correctly, or to ensure that data sent to them is correctly formatted.
Example Code
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| local aBlob = blob(8); | |
| for (local i = 0 ; i < 8 ; i++) { | |
| aBlob.writen(i, 'c'); | |
| } | |
| // aBlob is '00 01 02 03 04 05 06 07' | |
| aBlob.swap2(); | |
| // my_blob is now '01 00 03 02 05 04 07 06' |