Idea - big and little endian data areas using named address spaces

[David Brown]

Would it be possible to use the named address space syntax to implement 
reverse-endian data?  Conversion between little-endian and big-endian 
data structures is something that turns up regularly in embedded 
systems, where you might well be using two different architectures with 
different endianness.  Some compilers offer direct support for endian 
swapping, but gcc has no neat solution.  You can use the 
__builtin_bswap32 (but no __builtin_bswap16?) function in recent 
versions of gcc, but you still need to handle the swapping explicitly.

Named address spaces would give a very neat syntax for using such 
byte-swapped areas.  Ideally you'd be able to write something like:

__swapendian stuct { int a; short b; } data;

and every access to data.a and data.b would be endian-swapped.  You 
could also have __bigendian and __litteendian defined to __swapendian or 
blank depending on the native ordering of the target.


I've started reading a little about how named address spaces work, but I 
don't know enough to see whether this is feasible or not.


Another addition in a similar vein would be __nonaligned, for targets 
which cannot directly access non-aligned data.  The loads and stores 
would be done byte-wise for slower but correct functionality.