fluencelabs/tendermint
1
0
Fork 0
mirror of https://github.com/fluencelabs/tendermint synced 2025-06-23 09:41:38 +00:00
Code Issues Projects Releases Wiki Activity

bit_array: Simplify subtraction

Browse Source 
also, fix potential bug in Or function
This commit is contained in:
ValarDragon
2018-10-02 16:03:59 -07:00
committed by Anton Kaliaev
parent c94133ed1b
commit 0755a5203d
3 changed files with 47 additions and 103 deletions
Download Patch File Download Diff File Expand all files Collapse all files

44
libs/common/bit_array.go
View File

@ -119,14 +119,13 @@ func (bA *BitArray) Or(o *BitArray) *BitArray {
}
bA.mtx.Lock()
o.mtx.Lock()
defer func() {
bA.mtx.Unlock()
o.mtx.Unlock()
}()
c := bA.copyBits(MaxInt(bA.Bits, o.Bits))
for i := 0; i < len(c.Elems); i++ {
smaller := MinInt(len(bA.Elems), len(o.Elems))
for i := 0; i < smaller; i++ {
c.Elems[i] |= o.Elems[i]
}
bA.mtx.Unlock()
o.mtx.Unlock()
return c
}
@ -173,8 +172,9 @@ func (bA *BitArray) not() *BitArray {
}
// Sub subtracts the two bit-arrays bitwise, without carrying the bits.
// This is essentially bA.And(o.Not()).
// If bA is longer than o, o is right padded with zeroes.
// Note that carryless subtraction of a - b is (a and not b).
// The output is the same as bA, regardless of o's size.
// If bA is longer than o, o is right padded with zeroes
func (bA *BitArray) Sub(o *BitArray) *BitArray {
if bA == nil || o == nil {
// TODO: Decide if we should do 1's complement here?
@ -182,24 +182,20 @@ func (bA *BitArray) Sub(o *BitArray) *BitArray {
}
bA.mtx.Lock()
o.mtx.Lock()
defer func() {
bA.mtx.Unlock()
o.mtx.Unlock()
}()
if bA.Bits > o.Bits {
c := bA.copy()
for i := 0; i < len(o.Elems)-1; i++ {
c.Elems[i] &= ^o.Elems[i]
}
i := len(o.Elems) - 1
if i >= 0 {
for idx := i * 64; idx < o.Bits; idx++ {
c.setIndex(idx, c.getIndex(idx) && !o.getIndex(idx))
}
}
return c
// output is the same size as bA
c := bA.copyBits(bA.Bits)
// Only iterate to the minimum size between the two.
// If o is longer, those bits are ignored.
// If bA is longer, then skipping those iterations is equivalent
// to right padding with 0's
smaller := MinInt(len(bA.Elems), len(o.Elems))
for i := 0; i < smaller; i++ {
// &^ is and not in golang
c.Elems[i] &^= o.Elems[i]
}
return bA.and(o.not()) // Note degenerate case where o == nil
bA.mtx.Unlock()
o.mtx.Unlock()
return c
}
// IsEmpty returns true iff all bits in the bit array are 0