copy performance in user space vs. kernel

The kernel used a stream-lined access, while the standard glibc didn't. You may adapt arch/nios2/lib/memcpy.c instead of glibc.

- Hippo

commit b3eaa1c911109e99c6cd06ec9b91a86a34929fa6

nios2: memcpy with stream-lined memory access

As sdram has long access latency, the total access time can be reduced

with sequential access in the same page.

This patch unrolls the copy loop and stream-lines the memory access as

(read x8 + write x8) for aligned source and destination, or

(read x4 + write x4) for unalinged, using registers for buffer.