On Mon, 19 Oct 2015, Bo Berglund wrote:
I am making a control program for a data collection system using FPC +
Lazarus on a Raspberry Pi2 platform. I will use a number of Delphi
units, which implement the communications and data handling needs in a
way that works fine on a Windows platform.
While looking over existing code I see that there are instructions to
modify received data from the instrument by reversing the byte order.
The reason for that was that the instrument is based on a Motorola
controller and it uses the opposite byte order as in the Intel CPU:s
on the PC. Since download is of binary data areas in the instrument
the byte order change was necessary for all multi-byte data like word
and integers as well as real (floating point 32 bit values).
Now I wonder if it will be necessary also on an ARM platform like the
RPi2?
Is there a function or such to interrogate the byte order of the
platform FPC runs on? So that I could add a test at the start of
download to check if swapping is needed?
There are compiler defines defines that give you the endianness.
{$IFDEF ENDIAN_BIG}
{$IFDEF ENDIAN_LITTLE}
And
{$IFDEF FPC_LITTLE_ENDIAN}
{$IFDEF FPC_BIG_ENDIAN}
Then there are BeToN, LeTon and and other functions that force a certain
endianness or convert from a certain endianness to native endianness.
Michael.
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