AWARE SYSTEMS
TIFF and LibTiff Mail List Archive

Thread

1994.09.16 04:17 "TIFF Bit Ordering Versus Fill Order", by John M Davison
[...]
1994.09.19 11:48 "Re: TIFF Bit Ordering Versus Fill Order", by Niles Ritter
1994.09.19 22:48 "Re: TIFF Bit Ordering Versus Fill Order", by Sam Leffler
1994.09.20 07:00 "Re: TIFF Bit Ordering Versus Fill Order", by Fredrik Lundh
[...]

1994.09.20 07:00 "Re: TIFF Bit Ordering Versus Fill Order", by Fredrik Lundh

However, a possible way to define host bit order would be to use the C bit-field struct operations.

Is this a compiler-implementation dependent approach?

ANSI C, Section 3.5.2.1:

    "The order of allocation of bit-fields within a unit
    (high-order to low-order or low-order to high-order) is
    implementation-defined."

The spec also states that it "need not be possible to express the address of each individual bit of an object", and that shifting n bits to the left is the same as multiplying by 2 raised to the power n.

To sum that up, there is no such thing as a "host bit order" when hacking C (at least not with the same meaning as "host byte order").

For additional reading on bit and byte orders, see IEN 137.

        /F