Documentation
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Overview ¶
rollsum provides an implementation of a rolling checksum - a checksum that's efficient to advance a byte or more at a time. It is inspired by the rollsum in rsync, but differs in that the internal values used are 32bit integers - to make a conformant implementation, a find a replace on "32" should be almost sufficient (although it would be highly recommended to test against known values from the original implementation).
Rollsum32 supports the hash.Hash implementation, but is not used much in go-sync, mostly in order to share and access the underlying circular buffer storage, and use the implementation as efficiently as possible.
Index ¶
- Constants
- type Rollsum32
- type Rollsum32Base
- func (r *Rollsum32Base) AddAndRemoveBytes(add []byte, remove []byte, length int)
- func (r *Rollsum32Base) AddByte(b byte)
- func (r *Rollsum32Base) AddBytes(bs []byte)
- func (r *Rollsum32Base) GetSum(b []byte)
- func (r *Rollsum32Base) RemoveByte(b byte, length int)
- func (r *Rollsum32Base) RemoveBytes(bs []byte, length int)
- func (r *Rollsum32Base) Reset()
- func (r *Rollsum32Base) SetBlock(block []byte)
- func (r *Rollsum32Base) Size() int
Constants ¶
const FULL_BYTES_16 = (1 << 16) - 1
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Rollsum32 ¶
type Rollsum32 struct {
Rollsum32Base
// contains filtered or unexported fields
}
Rollsum32 is a rolling checksum implemenation inspired by rsync, but with 32bit internal values Create one using NewRollsum32
func NewRollsum32 ¶
func (*Rollsum32) GetLastBlock ¶
type Rollsum32Base ¶
type Rollsum32Base struct {
// contains filtered or unexported fields
}
The specification of hash.Hash is such that it cannot be implemented without implementing storage but the most optimal storage scheme depends on usage of the circular buffer & hash
func NewRollsum32Base ¶
func NewRollsum32Base(blockSize uint) *Rollsum32Base
Rollsum32Base decouples the rollsum algorithm from the implementation of hash.Hash and the storage the rolling checksum window this allows us to write different versions of the storage for the distinctly different use-cases and optimize the storage with the usage pattern.
func (*Rollsum32Base) AddAndRemoveBytes ¶
func (r *Rollsum32Base) AddAndRemoveBytes(add []byte, remove []byte, length int)
func (*Rollsum32Base) AddByte ¶
func (r *Rollsum32Base) AddByte(b byte)
Add a single byte into the rollsum
func (*Rollsum32Base) AddBytes ¶
func (r *Rollsum32Base) AddBytes(bs []byte)
func (*Rollsum32Base) GetSum ¶
func (r *Rollsum32Base) GetSum(b []byte)
Puts the sum into b. Avoids allocation. b must have length >= 4
func (*Rollsum32Base) RemoveByte ¶
func (r *Rollsum32Base) RemoveByte(b byte, length int)
Remove a byte from the end of the rollsum Use the previous length (before removal)
func (*Rollsum32Base) RemoveBytes ¶
func (r *Rollsum32Base) RemoveBytes(bs []byte, length int)
func (*Rollsum32Base) SetBlock ¶
func (r *Rollsum32Base) SetBlock(block []byte)
Set a whole block of blockSize
Source Files