Make GetState() handle overflowed state and 0 path to root
Fix GetState() so that it deals correctly with an overflowed state in
which the path to root is entirely zero. We don't try to salvage
the DCHECK for now. Fix the stated invariants to be more consistent
with the code.
Bug: 69564627
Test: AOSP builds & runs. Host tests pass.
Change-Id: Idd975f03d4292e4fc52ad7714bbb2b1b98e17f96
diff --git a/runtime/base/bit_string.h b/runtime/base/bit_string.h
index a2164f3..bfbe8ea 100644
--- a/runtime/base/bit_string.h
+++ b/runtime/base/bit_string.h
@@ -114,7 +114,7 @@
/**
* BitString
*
- * MSB LSB
+ * lsb (least significant bit) msb
* +------------+------------+------------+-----+------------+
* | | | | | |
* | Char0 | Char1 | Char2 | ... | CharN |
@@ -131,8 +131,9 @@
* "ABCDE...K" := [A,B,C,D,E, ... K] + [0]*(N-idx(K)) s.t. N >= K.
* // Padded with trailing 0s to fit (N+1) bitstring chars.
* MaxBitstringLen := N+1
- * StrLen(Bitstring) := MaxBitStringLen - | forall char in CharI..CharN : char == 0 AND Char(I-1) != 0 |
- * // Maximum length - the # of consecutive trailing zeroes.
+ * StrLen(Bitstring) := I s.t. (I == 0 OR Char(I-1) != 0)
+ * AND forall char in CharI..CharN : char == 0
+ * // = Maximum length - the # of consecutive trailing zeroes.
* Bitstring[N] := CharN
* Bitstring[I..N) := [CharI, CharI+1, ... CharN-1]
*
@@ -278,8 +279,8 @@
private:
friend std::ostream& operator<<(std::ostream& os, const BitString& bit_string);
- // Data is stored with the "highest" position in the least-significant-bit.
- // As positions approach 0, the bits are stored with increasing significance.
+ // Data is stored with the first character in the least-significant-bit.
+ // Unused bits are zero.
StorageType storage_;
};