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- // 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 (
- "errors"
- "github.com/ethereum/go-ethereum/core/types"
- )
- var (
- // errSectionOutOfBounds is returned if the user tried to add more bloom filters
- // to the batch than available space, or if tries to retrieve above the capacity.
- errSectionOutOfBounds = errors.New("section out of bounds")
- // errBloomBitOutOfBounds is returned if the user tried to retrieve specified
- // bit bloom above the capacity.
- errBloomBitOutOfBounds = errors.New("bloom bit out of bounds")
- )
- // Generator takes a number of bloom filters and generates the rotated bloom bits
- // to be used for batched filtering.
- type Generator struct {
- blooms [types.BloomBitLength][]byte // Rotated blooms for per-bit matching
- sections uint // Number of sections to batch together
- nextSec uint // Next section to set when adding a bloom
- }
- // NewGenerator creates a rotated bloom generator that can iteratively fill a
- // batched bloom filter's bits.
- func NewGenerator(sections uint) (*Generator, error) {
- if sections%8 != 0 {
- return nil, errors.New("section count not multiple of 8")
- }
- b := &Generator{sections: sections}
- for i := 0; i < types.BloomBitLength; i++ {
- b.blooms[i] = make([]byte, sections/8)
- }
- return b, nil
- }
- // AddBloom takes a single bloom filter and sets the corresponding bit column
- // in memory accordingly.
- func (b *Generator) AddBloom(index uint, bloom types.Bloom) error {
- // Make sure we're not adding more bloom filters than our capacity
- if b.nextSec >= b.sections {
- return errSectionOutOfBounds
- }
- if b.nextSec != index {
- return errors.New("bloom filter with unexpected index")
- }
- // Rotate the bloom and insert into our collection
- byteIndex := b.nextSec / 8
- bitIndex := byte(7 - b.nextSec%8)
- for byt := 0; byt < types.BloomByteLength; byt++ {
- bloomByte := bloom[types.BloomByteLength-1-byt]
- if bloomByte == 0 {
- continue
- }
- base := 8 * byt
- b.blooms[base+7][byteIndex] |= ((bloomByte >> 7) & 1) << bitIndex
- b.blooms[base+6][byteIndex] |= ((bloomByte >> 6) & 1) << bitIndex
- b.blooms[base+5][byteIndex] |= ((bloomByte >> 5) & 1) << bitIndex
- b.blooms[base+4][byteIndex] |= ((bloomByte >> 4) & 1) << bitIndex
- b.blooms[base+3][byteIndex] |= ((bloomByte >> 3) & 1) << bitIndex
- b.blooms[base+2][byteIndex] |= ((bloomByte >> 2) & 1) << bitIndex
- b.blooms[base+1][byteIndex] |= ((bloomByte >> 1) & 1) << bitIndex
- b.blooms[base][byteIndex] |= (bloomByte & 1) << bitIndex
- }
- b.nextSec++
- return nil
- }
- // Bitset returns the bit vector belonging to the given bit index after all
- // blooms have been added.
- func (b *Generator) Bitset(idx uint) ([]byte, error) {
- if b.nextSec != b.sections {
- return nil, errors.New("bloom not fully generated yet")
- }
- if idx >= types.BloomBitLength {
- return nil, errBloomBitOutOfBounds
- }
- return b.blooms[idx], nil
- }
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