Little Endianess to Big Endianess

[6HEbO1]

Hi,

Does anybody now how to convert a negative 2-byte integer on a Little Endian Operating System/CPU to a machine with Big Endian (Motorola)??

Any help would be welcome.

Kind regards,
6HEbo1

 

[xwb]

What compiler/OS are you using? Which version of Fortran are you using? This is quite easy in C, a bit more cummbersome in Fortran.

What form is the data in: is it in code or in a binary file?

How do you wish to output the data: writing to hardware, writing to a binary file or output as numbers?

 

[6HEbO1]

Hi xwb,

In and output only in code. In Fortran 90 on a VMS system.

Like:

X and Y as var in code

X = -14
Y = ??

Y will be send to the BE machine

What I've read now it should be for negative numbers the 2th complement + 1 and then a byteswap? Is that correct? If so I'll try that myself.

 

[xwb]

That is correct for converting a +ve to a -ve number. Does your compiler have the functions ishft, iand, ior

!       ,-- move bottom 8 bits to the top
!       |                       ,-- move top 8 bits to the bottom           
y = ior(ishft(iand(x, 255), 8), ishft(x, -8))
!
! print numbers in hex to ensure byteswap
print '(I6, 1X, Z4, 1X, I6, 1X, Z4)', x, x, y, y

 

[6HEbO1]

Yes it does have these functions.

Thx!