Safe Haskell	Safe
Language	Haskell2010

Data.Attoparsec.VarWord

Description

We define Attoparsec Parsers for several different variable-length integer encoding schemes. These schemes are useful for transmitting numerical data in a more compact form than would be available from simple big- or little-endian encoding of the values.

Synopsis

Documentation

varWordBe :: (Bits a, Integral a) => Parser a Source #

Decode a big-endian (most significant byte first), variable-length encoded value.

+-- Keep reading
|        +-- Keep reading
|        |        +-- Stop
v        v        v
10000001 10010000 00100000
 |<--->|  |<--->|  |<--->|
 Data(A)  Data(B)  Data(C)

  ==   1 0010000 0100000 == 18464
     (A) (B)     (C)

>>> parseOnly varWordBe "\129\144\32"
Right 18464

denseVarWordBe :: (Bits a, Integral a) => Parser a Source #

Decode a big-endian (least significant byte first), variable length encoded value where the continuation byte is used to carry data also.

+-- Keep reading
|        +-- Keep reading
|        |        +-- Stop
v        v        v
10000001 10010000 00100000
 |<--->|  |<--->|  |<--->|
 Data(A)  Data(B)  Data(C)

  ==  10 0010001 0100000 == 34976
   (A+1) (B+1)   (C)

>>> parseOnly denseVarWordBeP "\129\144\32"
Right 34976

varWordLe :: (Bits a, Integral a) => Parser a Source #

Decode a little-endian (least significant byte first), variable length encoded value.

+-- Keep reading
|        +-- Keep reading
|        |        +-- Stop
v        v        v
10000001 10010000 00100000
 |<--->|  |<--->|  |<--->|
 Data(A)  Data(B)  Data(C)

  == 100000 0010000 0000001 == 526337
     (C)    (B)     (A)

>>> parseOnly varWordLe "\129\144\32"
Right 526337