1 files changed, 63 insertions, 0 deletions
diff --git a/core/bloombits/utils.go b/core/bloombits/utils.go
new file mode 100644
index 000000000..d0755cb65
--- /dev/null
+++ b/core/bloombits/utils.go
@@ -0,0 +1,63 @@
+// Copyright 2017 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+package bloombits
+
+import (
+	"github.com/ethereum/go-ethereum/core/types"
+)
+
+const BloomLength = 2048
+
+// BloomBitsCreator takes SectionSize number of header bloom filters and calculates the bloomBits vectors of the section
+type BloomBitsCreator struct {
+	blooms              [BloomLength][]byte
+	sectionSize, bitIndex uint64
+}
+
+func NewBloomBitsCreator(sectionSize uint64) *BloomBitsCreator {
+	b := &BloomBitsCreator{sectionSize: sectionSize}
+	for i, _ := range b.blooms {
+		b.blooms[i] = make([]byte, sectionSize/8)
+	}
+	return b
+}
+
+// AddHeaderBloom takes a single bloom filter and sets the corresponding bit column in memory accordingly
+func (b *BloomBitsCreator) AddHeaderBloom(bloom types.Bloom) {
+	if b.bitIndex >= b.sectionSize {
+		panic("too many header blooms added")
+	}
+
+	byteIdx := b.bitIndex / 8
+	bitMask := byte(1) << byte(7-b.bitIndex%8)
+	for bloomBitIdx, _ := range b.blooms {
+		bloomByteIdx := BloomLength/8 - 1 - bloomBitIdx/8
+		bloomBitMask := byte(1) << byte(bloomBitIdx%8)
+		if (bloom[bloomByteIdx] & bloomBitMask) != 0 {
+			b.blooms[bloomBitIdx][byteIdx] |= bitMask
+		}
+	}
+	b.bitIndex++
+}
+
+// GetBitVector returns the bit vector belonging to the given bit index after header blooms have been added
+func (b *BloomBitsCreator) GetBitVector(idx uint) []byte {
+	if b.bitIndex != b.sectionSize {
+		panic("not enough header blooms added")
+	}
+
+	return b.blooms[idx][:]
+}