[erlang-questions] sub-byte endianness in bit syntax

David Mercer <>
Thu Aug 16 22:30:17 CEST 2007

At Thursday, August 16, 2007 14:47, Michael McDaniel wrote:
> On Thu, Aug 16, 2007 at 06:54:03PM +0100, Tony Finch wrote:
> > How do you tell Erlang to fill bytes little-end first?
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>  documentation, programming examples, section 4.3
. . .

I think what Tony is asking about is little-endian *bit* order as opposed to
byte order.

I think Erlang's endianness is at the byte level, not bit level.  Therefore,

	<< 2#11110000:8/little >> = << 2#11110000:8/big >>

regardless of the endianness, since it is only one byte, and the bits within
a byte are filled in big-endian order always.  Once we go over a byte
boundary, however, endianness does matter:

	<< 2#11110000:16/little >> = << 2#11110000:16/big >>

will not match.

This request may be related to EEP #4
(http://www.erlang.org/eeps/eep-0004.html), since it seems to be related to
bit streams as opposed to byte streams.

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