Re: Simple Data Endianness

[Optikos <ZUERCHER_Andreas@outlook.com>]

On Thursday, February 13, 2020 at 5:10:44 AM UTC-6, Dmitry A. Kazakov wrote:
> On 2020-02-13 10:42, guijarrockGuijarro wrote:
> 
> > The problem I present today is related to the coexistence between big-endian and little-endian application data.
> 
> How low-level representation aspect might be relevant to application data?

If the exchange of app data between 2 or more computers is word-wise binary instead of byte-wise textual, such as via binary-formatted files or via binary-formatted datagrams/byte-streams as payload of networking protocols.

> >     type Colour is (BLACK,YELLOW,WHITE,RED);
> >     for Colour'SIZE use 32;
> > 
> > Is there any analogous way of doing this as in the case of compound types?
> 
> Should it include middle-endian packed binary-coded decimals with memory 
> parity bits? (:-))

middle-endian:  Yes, if porting to PDP11, Honeywell 316, and the like. ;^)

parity bits:  Yes, if porting to Prime 50 series that had mark-parity ASCII characters 128 to 255 packed 2 at a time into 16-bit bytes.  ;^)

BCD: Yes, if the app data was written to a file in BCD, such as easily so by a BCD capable language (e.g., COBOL, Ada).  This one is less of a joke, because these COBOL-written app-data files are commonplace on IBM mainframes, especially if the new work is Ada on non-mainframes reading in the data downloaded from mainframes.