github.com/m3db/m3@v1.5.0/src/m3em/checksum/types.go (about)

     1  // Copyright (c) 2017 Uber Technologies, Inc.
     2  //
     3  // Permission is hereby granted, free of charge, to any person obtaining a copy
     4  // of this software and associated documentation files (the "Software"), to deal
     5  // in the Software without restriction, including without limitation the rights
     6  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     7  // copies of the Software, and to permit persons to whom the Software is
     8  // furnished to do so, subject to the following conditions:
     9  //
    10  // The above copyright notice and this permission notice shall be included in
    11  // all copies or substantial portions of the Software.
    12  //
    13  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    14  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    15  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    16  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    17  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    18  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    19  // THE SOFTWARE.
    20  
    21  package checksum
    22  
    23  import (
    24  	"hash/crc32"
    25  )
    26  
    27  // Fn returns a checksum of the provided bytes
    28  func Fn(b []byte) uint32 {
    29  	return crc32.ChecksumIEEE(b)
    30  }
    31  
    32  // Accumulator accrues checksums
    33  type Accumulator interface {
    34  	// Current returns the current checksum value
    35  	Current() uint32
    36  
    37  	// Update updates accrued checksum using provided bytes
    38  	Update(b []byte) uint32
    39  }
    40  
    41  // NewAccumulator returns a new accumulator
    42  func NewAccumulator() Accumulator {
    43  	return &accum{
    44  		checksum: 0,
    45  	}
    46  }
    47  
    48  type accum struct {
    49  	checksum uint32
    50  }
    51  
    52  func (a *accum) Current() uint32 {
    53  	return a.checksum
    54  }
    55  
    56  func (a *accum) Update(b []byte) uint32 {
    57  	a.checksum = crc32.Update(a.checksum, crc32.IEEETable, b)
    58  	return a.checksum
    59  }