base: Add classes that encapsulate a channel address

There are cases where the memory system needs to reason about
channel-local addresses. These are currently represented using the
Addr and AddrRange classes. This is not ideal since it doesn't provide
any type safety when working with global addresses and channel-local
addresses. This is particularly problematic when porting existing
components to work in multi-channel configurations.

This changeset introduces the new ChannelAddr and ChannelAddrRange
classes. These classes encapsulate channel-local addresses in a
contiguous address space. These can, for example, be used in a memory
controller to represent a flat address space when calculating timings
or in a sectored cache.

Change-Id: I45d4061ebc8507a10d0a4577b28796dc5ec7a469
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/21600
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/base/SConscript

@@ -40,6 +40,7 @@ Source('imgwriter.cc')
 Source('bmpwriter.cc')
 Source('callback.cc')
 GTest('callback.test', 'callback.test.cc', 'callback.cc')
+Source('channel_addr.cc')
 Source('cprintf.cc', add_tags='gtest lib')
 GTest('cprintf.test', 'cprintf.test.cc')
 Source('debug.cc')
@@ -90,6 +91,7 @@ if env['USE_HDF5']:
 GTest('addr_range.test', 'addr_range.test.cc')
 GTest('addr_range_map.test', 'addr_range_map.test.cc')
 GTest('bitunion.test', 'bitunion.test.cc')
+GTest('channel_addr.test', 'channel_addr.test.cc')
 GTest('circlebuf.test', 'circlebuf.test.cc')
 GTest('circular_queue.test', 'circular_queue.test.cc')
 GTest('sat_counter.test', 'sat_counter.test.cc')