A Delphi project "DeleD 3-D" which I try to convert, has unit_PNGSupport with method:

function TPNGProcessor.SwapLong( const aValue: Cardinal ): Cardinal; assembler;
asm
    mov eax, aValue
    bswap eax;
end;

What would be a cross-platform replacement?

I read that bswap is used for converting big-endian (Intel) format to little-endian (Motorolla etc.) format.
However this a an old Delphi app, Win32 only.

Later PNG support functions can be replaced with something else, bu that is another story.

Regards,
Juha

2013/2/6 Juha Manninen :

I read that bswap is used for converting big-endian (Intel) format to little-endian (Motorolla etc.) format. However this a an old Delphi app, Win32 only.

I am confused. Intel i386 is little endian. Motorola Powerpc is big endian.

Vincent

function TPNGProcessor.SwapLong( const aValue: Cardinal ): Cardinal;
begin
    result := BeToN(aValue);
end;

What Vincent said, and...

There was a (recent) discussion about Swap and BEtoN, on Lazarus list. (message titles: "Unpack of PHP", mostly on 4/02/2013)

Lukasz

I copied it from here:
http://asm.inightmare.org/opcodelst/index.php?op=BSWAP

I think the author was confused. I am always confused, too, because the big/little endian thing is named wrong IMO.
In human readable numbers, reading from left to right, big numbers (MSB) come first and little numbers (LSB) last.
In essense it is a "little endian" notation as it ends with little numbers. Motorola 68000 and others use the same logic (MSB - LSB) but for some reason it is called " big endian" while Intel which has it upside down, is called "little endian".
IIRC the names refer to memory layout, how those registers are written to memory.

Anyway, I am confused but it does not matter because there are functions made by someone else and I don't need to think of the details. :)

Regards,
Juha

Jeppe Græsdal Johansen wrote

function TPNGProcessor.SwapLong( const aValue: Cardinal ): Cardinal; begin result := BeToN(aValue); end;

Thanks, it works!
There are so many functions in FPC libraries which I don't know anything about. This was one of them.

Regards,
Juha

It could be that BeToN is the wrong function (it depends on how the method is used). What it does is the following: if the target cpu is big endian (m68k, powerpc) then just return the value, otherwise (i386) swap the endianess.

So you should check what SwapLong is really used for.

There are three possible functions:
BeToN (as mentioned above)
LeToN (leave as is if little endian, convert otherwise) SwapEndian (change always)

Regards,
Sven

I wonder whether I could ask a silly question here: is there a way of processing the RTL documentation to extract the description as a single line, so that it can be run through a permuted-index generator?

For example, if index-generation was restricted to ten words the lines

BEToN will rearrange the bytes in a Big-Endian number LEToN will rearrange the bytes in a Little-Endian number

run through the unix ptx utility would index under "Endian" (amongst others).