Martin Guy wrote:
armv4t is the minimum
instruction set required for EABI, and runs on later architectures
fine.
While this is currently true for existing gcc, I'm not sure it's
necessarily true overall. At some cost in speed and code size, it does
appear to be possible to build code for armv4, (sans "t"), which is
upward compatible and also interwork safe.
The only difference I am aware of between the two is the introduction
of a CLZ (clear block of memory to zero) instruction. The rest of the
changes in the v5-implementing cores are hardware performance
increases to run the same order code faster per MHz.
As I understand it, all assignments to pc on armv5* have the same mode
conversion as the bx instruction. This makes it possible to branch and
return using more efficient instruction sequences. I think thumb is
also mandated on armv5 and later, though I could be mistaken.
--rich
--
To UNSUBSCRIBE, email to [EMAIL PROTECTED]
with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
