tree b3f6738d864b6c7faded3de2f46013f977eac7b5
parent 37331e6765e6283bd34240f6e096ea934f0fed15
author Aaron Green <aarongreen@google.com> 1520635794 -0800
committer CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org> 1521224401 +0000

[bitmap] Add reverse scanning

This CL adds RScan and RFind to complement Scan and Find, respectively.
The functions find the last occurences of a non-matching bit or run of
matching bits, instead of the first.

The interface for Scan and Find has also slightly changed: while
returning "bitmax" made some sense on failure before, returning "bitoff"
doesn't for the reverse versions since it would be a valid offset.
Returning "bitoff-1" is similarly problematic, as bitoff may be 0.
Instead, Scan now returns a bool, and Find does not set "out" in their
respective failure cases.

ZX-1781 #comment Fixed

Change-Id: Ied08f8c74bca17e7b537d16075a2005e00d536fc