Copyright	(C) 2015 Nicolas Trangez 2015 Klaus Post 2015 Backblaze
License	MIT (see the file LICENSE)
Maintainer	Nicolas Trangez <ikke@nicolast.be>
Stability	provisional
Safe Haskell	None
Language	Haskell2010
Extensions	Cpp ScopedTypeVariables DeriveDataTypeable ExplicitForAll

Data.ReedSolomon

Contents

Core API
Data conversion utilities
Exceptions
Determining runtime SIMD instruction support

Description

This module implements the core Reed-Solomon data encoding and reconstruction routines.

Synopsis

Core API

data Encoder Source

A Reed-Solomon encoder.

Instances

Eq Encoder Source
Show Encoder Source

new Source

Arguments

:: MonadThrow m
=> Int	Number of data shards ([0, 255])
-> Int	Number of parity shards ([0, ])
-> m Encoder

Construct a new Encoder.

Throws InvalidNumberOfShards when dataShards or parityShards is out of range.

An Encoder can safely be reused between encoding and reconstruction rounds, as well as shared between threads.

type Matrix = Vector (Vector Word8) Source

A row-major Matrix of bytes.

encode Source

Arguments

:: MonadThrow m
=> Encoder	Encoder to use
-> Matrix	Data shards
-> m Matrix

Encode some data shards into parity shards.

The number of rows in the given matrix must match the number of data shards the Encoder requires, otherwise InvalidNumberOfShards is thrown. If all shards are empty, EmptyShards is thrown. Similarly, when shards are of inconsistent length, InvalidShardSize is thrown.

verify :: MonadThrow m => Encoder -> Matrix -> m Bool Source

Verify the code chunks against the data.

This function will re-encode the data chunks, and validate the code chunks in the given Matrix are equal.

reconstruct Source

Arguments

:: MonadThrow m
=> Encoder	Encoder to use
-> Vector (Maybe (Vector Word8))	Partial data and parity shards
-> m Matrix	Reconstructed data and parity shards

Reconstruct partial data.

Data conversion utilities

split :: MonadThrow m => Encoder -> Vector Word8 -> m Matrix Source

Split data into shards that can be encoded by the given Encoder.

If required, the last shard is padded with zeros to match size.

join :: MonadThrow m => Encoder -> Matrix -> Int -> m (Vector Word8) Source

Join shards into a single Vector of given size.

Note: This function concatenates all data through copies, which is inefficient. When writing the data to a file or socket, consider doing so without joining in-memory.

Exceptions

data ShardType Source

Enumeration of kinds of shards.

Constructors

DataShard
ParityShard
AnyShard

Instances

Bounded ShardType Source
Enum ShardType Source
Eq ShardType Source
Show ShardType Source

data ValueError Source

Exception type used to denote invalid input.

Constructors

InvalidNumberOfShards ShardType Int	Invalid number of shards
EmptyShards	All shards are empty
InvalidShardSize	A shard of invalid size was passed
InvalidDataSize	The length of the passed data is invalid

Instances

Eq ValueError Source
Show ValueError Source
Exception ValueError Source

Determining runtime SIMD instruction support

data SIMDInstructions Source

Enumeration of SIMD instruction sets.

Constructors

Generic
SSE2
SSSE3
AVX
AVX2
NEON
AltiVec

Instances

Bounded SIMDInstructions Source
Enum SIMDInstructions Source
Eq SIMDInstructions Source
Ord SIMDInstructions Source
Show SIMDInstructions Source

simdInstructions :: IO (Maybe SIMDInstructions) Source

Retrieve the SIMD instruction set used by native Galois field operations.

Returns Nothing when the library is compiled without SIMD support, otherwise Just the runtime-determined SIMD instruction set used for optimized Galois field calculations.