[fpc-pascal] Binary compatibility between Intel CPU and PowerPC CPU

Adriaan van Os fpc at microbizz.nl
Tue Sep 16 18:44:04 CEST 2008

Adriaan van Os wrote:
> Roland Turcan wrote:
>> Hello FPC-Pascal users discussions!
>> What is the best way to keep the binary compatibility among different
>> CPU architectures.
>> I need to make our own database engine compatible and other binary
>> files, that user still can use our data from i386 or PowerPC computer.
>> I really don't like the idea to change the order of all numeric
>> variables on PowerPC, because it costs time of CPU.
>> There must be easier way how to keep the compatibility.
>> Could you give me some hints for better solution.
> Whether you "like the idea" or not, the best way is as follows:
> - add a byte to the header of source data that indicates the endianness, 
> high-endian for PowerPC, low-endian for i386
> - perform byte swapping if the endianness of source data is different 
> from the endianness of the current CPU
> With "source data" I mean
> - reading files
> - reading data over a network
> This is best built-into a streaming toolbox, so that it happens 
> automatically.

I forgot to mention:
- write data in the endianness of the current CPU

To me, this is obvious, but for example Postgres always transfers data high-endian over a network, 
which is ridicuous. So, for example if they send binary data from an i386 machine to another i386 
machine, they perform byte-swapping twice, unnecessary,


Adriaan van Os

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