ARM - typing error: unknown primitive: `REV'

[tfaoliveira]

It seems that REV is not supported yet. It would be useful to improve this armv7m sha256 implementation.
When compiling the following piece of code:

export fn trev(reg u32 a) -> reg u32
{
  a = #REV(a);
  return a;
}

I get:

jasminc -arch=arm-m4 -o rev.s rev.jazz
warning: support of the ARMv7 architecture is experimental
"rev.jazz", line 3 (7-10):
typing error: unknown primitive: `REV'
make: *** [Makefile:2: rev.s] Error 1