scodec comes with a large number of predefined codecs and combinators.
This list is a work-in-progress overview over the predefined codecs.
| Name | Result Type | Description | Min Bits | Max Bits | Coding Examples |
|---|---|---|---|---|---|
bits |
scodec.bits.BitVector |
All the remaining bits | 0 | ∞ | bin"11010110101" ⇔ 11010110 101₂ (11 bits) |
bytes |
scodec.bits.ByteVector |
All the remaining bytes | 0 | ∞ | hex"5468697320697320" ⇔ 54 68 69 73 20 69 73 20₁₆ (8 bytes) |
byte |
Byte |
A single byte | 8 | 8 | 89: Byte ⇔ 59₁₆ (1 byte) |
ushort8 |
Short |
8-bit unsigned short | 8 | 8 | 240: Short ⇔ f0₁₆ (1 byte) |
short16 |
Short |
16-bit big-endian short | 16 | 16 | 0x1234: Short ⇔ 12 34₁₆ (2 bytes) |
int8 |
Int |
8-bit integer | 8 | 8 | 0x12 ⇔ 12₁₆ (1 byte) |
int16 |
Int |
16-bit big-endian integer | 16 | 16 | 0x1234 ⇔ 12 34₁₆ (2 bytes) |
int24 |
Int |
24-bit big-endian integer | 24 | 24 | 0x123456 ⇔ 12 34 56₁₆ (3 bytes) |
int32 |
Int |
32-bit big-endian integer | 32 | 32 | 0x12345678 ⇔ 12 34 56 78₁₆ (4 bytes) |
int64 |
Long |
64-bit big-endian integer | 64 | 64 | 0x12345678abcdefL ⇔ 00 12 34 56 78 ab cd ef₁₆ (8 bytes) |
uint2 |
Int |
2-bit unsigned integer | 2 | 2 | 0x3 ⇔ 11₂ (2 bits) |
uint4 |
Int |
4-bit unsigned integer | 4 | 4 | 0x6 ⇔ 0110₂ (4 bits) |
uint8 |
Int |
8-bit unsigned integer | 8 | 8 | 0xad ⇔ ad₁₆ (1 byte) |
uint16 |
Int |
16-bit big-endian unsigned integer | 16 | 16 | 0xadac ⇔ ad ac₁₆ (2 bytes) |
uint32 |
Long |
32-bit big-endian unsigned integer | 32 | 32 | 0x81234567L ⇔ 81 23 45 67₁₆ (4 bytes) |
int8L |
Int |
8-bit little-endian integer | 8 | 8 | 0x12 ⇔ 12₁₆ (1 byte) |
int16L |
Int |
16-bit little-endian integer | 16 | 16 | 0x1234 ⇔ 34 12₁₆ (2 bytes) |
int24L |
Int |
24-bit little-endian integer | 24 | 24 | 0x123456 ⇔ 56 34 12₁₆ (3 bytes) |
int32L |
Int |
32-bit little-endian integer | 32 | 32 | 0x12345678 ⇔ 78 56 34 12₁₆ (4 bytes) |
int64L |
Long |
64-bit little-endian integer | 64 | 64 | 0x12345678abcdefL ⇔ ef cd ab 78 56 34 12 00₁₆ (8 bytes) |
uint2L |
Int |
2-bit little-endian unsigned integer | 2 | 2 | 0x3 ⇔ 11₂ (2 bits) |
uint4L |
Int |
4-bit little-endian unsigned integer | 4 | 4 | 0x6 ⇔ 0110₂ (4 bits) |
uint8L |
Int |
8-bit little-endian unsigned integer | 8 | 8 | 0xad ⇔ ad₁₆ (1 byte) |
uint16L |
Int |
16-bit little-endian unsigned integer | 16 | 16 | 0xadac ⇔ ac ad₁₆ (2 bytes) |
uint32L |
Long |
32-bit little-endian unsigned integer | 32 | 32 | 0x81234567L ⇔ 67 45 23 81₁₆ (4 bytes) |
vint |
Int |
Variable-length big-endian integer | 1 | 5 | 0x01 ⇔ 01₁₆ (1 byte) 0x123 ⇔ a3 02₁₆ (2 bytes) 0x1234 ⇔ b4 24₁₆ (2 bytes) 0x12345 ⇔ c5 c6 04₁₆ (3 bytes) 0x123456 ⇔ d6 e8 48₁₆ (3 bytes) 0x1234567 ⇔ e7 8a 8d 09₁₆ (4 bytes) 0x12345678 ⇔ f8 ac d1 91 01₁₆ (5 bytes) |
vintL |
Int |
Variable-length little-endian integer | 1 | 5 | 0x123456 ⇔ c8 e8 56₁₆ (3 bytes) |
vlong |
Long |
Variable-length big-endian long | 1 | 9 | 0x81234567abcdL ⇔ cd d7 9e ab b4 a4 20₁₆ (7 bytes) |
vlongL |
Long |
Variable-length little-endian long | 1 | 9 | 0x81234567abcdL ⇔ a0 a4 b4 ab 9e d7 4d₁₆ (7 bytes) |
vpbcd |
Long |
Variable-length packed decimal longs | 1 | 9 | 1L ⇔ 0001₂ (4 bits) 123L ⇔ 00010010 0011₂ (12 bits) 12345L ⇔ 00010010 00110100 0101₂ (20 bits) 12345678901L ⇔ 00010010 00110100 01010110 01111000 10010000 0001₂ (44 bits) |
float |
Float |
32-bit big-endian IEEE 754 floating point number | 32 | 32 | 1.234234387f ⇔ 3f 9d fb 64₁₆ (4 bytes) |
floatL |
Float |
32-bit little-endian IEEE 754 floating point number | 32 | 32 | 1.234234387f ⇔ 64 fb 9d 3f₁₆ (4 bytes) |
double |
Double |
64-bit big-endian IEEE 754 floating point number | 64 | 64 | 1.234234387d ⇔ 3f f3 bf 6c 8e 7c 37 bd₁₆ (8 bytes) |
doubleL |
Double |
64-bit little-endian IEEE 754 floating point number | 64 | 64 | 1.234234387d ⇔ bd 37 7c 8e 6c bf f3 3f₁₆ (8 bytes) |
bool |
Boolean |
1-bit boolean | 1 | 1 | true ⇔ 1₂ (1 bit) |
ascii |
String |
US-ASCII String consuming remaining input |
0 | ∞ | "The lazy dog" ⇔ 54 68 65 20 6c 61 7a 79 20 64 6f 67₁₆ (12 bytes) |
utf8 |
String |
UTF8 String consuming remaining input |
0 | ∞ | "árvíztűrő ütvefúrógép" ⇔ c3 a1 72 76 c3 ad 7a 74 c5 b1 72 c5 91 20 c3 bc 74 76 65 66 c3 ba 72 c3 b3 67 c3 a9 70₁₆ (29 bytes) |
cstring |
String |
Null-terminated US-ASCII String |
0 | ∞ | "The lazy dog" ⇔ 54 68 65 20 6c 61 7a 79 20 64 6f 67 00₁₆ (13 bytes) |
ascii32 |
String |
US-ASCII String prefixed by 32-bit 2s complement big-endian size field |
32 | ∞ | "The lazy dog" ⇔ 00 00 00 0c 54 68 65 20 6c 61 7a 79 20 64 6f 67₁₆ (16 bytes) |
ascii32L |
String |
US-ASCII String prefixed by 32-bit 2s complement little-endian size field |
32 | ∞ | "The lazy dog" ⇔ 0c 00 00 00 54 68 65 20 6c 61 7a 79 20 64 6f 67₁₆ (16 bytes) |
utf8_32 |
String |
UTF8 String prefixed by 32-bit 2s complement big-endian size field |
32 | ∞ | "árvíztűrő ütvefúrógép" ⇔ 00 00 00 1d c3 a1 72 76 c3 ad 7a 74 c5 b1 72 c5 91 20 c3 bc 74 76 65 66 c3 ba 72 c3 b3 67 c3 a9 70₁₆ (33 bytes) |
utf8_32L |
String |
UTF8 String prefixed by 32-bit 2s complement little-endian size field |
32 | ∞ | "árvíztűrő ütvefúrógép" ⇔ 1d 00 00 00 c3 a1 72 76 c3 ad 7a 74 c5 b1 72 c5 91 20 c3 bc 74 76 65 66 c3 ba 72 c3 b3 67 c3 a9 70₁₆ (33 bytes) |
uuid |
java.util.UUID |
UUID as 2 64-bit big-endian longs |
128 | 128 | UUID.fromString("f41561aa-f759-4cde-ab07-c0c0cc0db8d8") ⇔ f4 15 61 aa f7 59 4c de ab 07 c0 c0 cc 0d b8 d8₁₆ (16 bytes) |
| Name | Description | Example usage | Example result type | Example Min Bits | Example Max Bits | Coding Examples |
|---|---|---|---|---|---|---|
constant |
Constant bits | constant(bin"110101") |
Unit |
6 | 6 | () ⇔ 110101₂ (6 bits) |
constant |
Constant bits | constant(bin"10") |
Unit |
2 | 2 | () ⇔ 10₂ (2 bits) |
constant |
Constant bytes | constant(hex"1234567890") |
Unit |
40 | 40 | () ⇔ 12 34 56 78 90₁₆ (5 bytes) |
constant |
Constant bytes | constant(hex"abcdef") |
Unit |
24 | 24 | () ⇔ ab cd ef₁₆ (3 bytes) |
constant |
Constant bytes | constant(0x42: Byte) |
Unit |
8 | 8 | () ⇔ 42₁₆ (1 byte) |
constant |
Constant bytes from integral | constant(0x2342: Short, 0x42: Short) |
Unit |
16 | 16 | () ⇔ 42 42₁₆ (2 bytes) |
constant |
Constant bytes from integral | constant(0x2342: Int, 0x42: Short) |
Unit |
16 | 16 | () ⇔ 42 42₁₆ (2 bytes) |
constant |
Constant bytes from integral | constant(0x2342: Long, 0x42: Short) |
Unit |
16 | 16 | () ⇔ 42 42₁₆ (2 bytes) |
| Name | Description | Example usage | Example result type | Example Min Bits | Example Max Bits | Coding Examples |
|---|---|---|---|---|---|---|
hlist |
Convert codec to HList | uint8.hlist |
Int :: HNil |
8 | 8 | 42 :: HNil ⇔ 2a₁₆ (1 byte) |
pairedWith |
Concat two codecs into a 2-tuple | uint8 pairedWith uint16 |
(Int, Int) |
24 | 24 | (0x12, 0x3456) ⇔ 12 34 56₁₆ (3 bytes) |
pairedWith |
Concat two codecs into a 2-tuple | uint8 pairedWith uint16 pairedWith cstring |
((Int, Int), String) |
24 | ∞ | ((0x12, 0x3456), "abc") ⇔ 12 34 56 61 62 63 00₁₆ (7 bytes) |
~ |
Concat two codecs into a 2-tuple | uint8 ~ uint16 |
(Int, Int) |
24 | 24 | (0x12, 0x3456) ⇔ 12 34 56₁₆ (3 bytes) |
~ |
Concat two codecs into a 2-tuple | uint8 ~ uint16 ~ cstring |
((Int, Int), String) |
24 | ∞ | ((0x12, 0x3456), "abc") ⇔ 12 34 56 61 62 63 00₁₆ (7 bytes) |
flattenLeftPairs |
Removes left tuple nesting and converts to HList | uint8 ~ uint16 ~ cstring flattenLeftPairs |
Int :: Int :: String :: HNil |
24 | ∞ | 0x12 :: 0x3456 :: "abc" :: HNil ⇔ 12 34 56 61 62 63 00₁₆ (7 bytes) |
dropLeft |
Concat two codecs discarding the Unit value of the left one | constant(0x12) dropLeft uint8 |
Int |
16 | 16 | 0x68 ⇔ 12 68₁₆ (2 bytes) |
~> |
Concat two codecs discarding the Unit value of the left one | constant(0x12) ~> uint8 |
Int |
16 | 16 | 0x68 ⇔ 12 68₁₆ (2 bytes) |
dropRight |
Concat two codecs discarding the Unit value of the right one | uint8 dropRight constant(0x12) |
Int |
16 | 16 | 0x68 ⇔ 68 12₁₆ (2 bytes) |
<~ |
Concat two codecs discarding the Unit value of the right one | uint8 <~ constant(0x12) |
Int |
16 | 16 | 0x68 ⇔ 68 12₁₆ (2 bytes) |
flatZip |
Concat two codecs into a 2-tuple where the second codec is choosen depending on the result of the first. | uint8 flatZip { case i if i < 100 ⇒ uint8; case _ ⇒ uint16 } |
(Int, Int) |
8 | ∞ | (23, 42) ⇔ 17 2a₁₆ (2 bytes) (112, 0x1234) ⇔ 70 12 34₁₆ (3 bytes) |
>>~ |
Concat two codecs into a 2-tuple where the second codec is choosen depending on the result of the first. | uint8 >>~ { case i if i < 100 ⇒ uint8; case _ ⇒ uint16 } |
(Int, Int) |
8 | ∞ | (23, 42) ⇔ 17 2a₁₆ (2 bytes) (112, 0x1234) ⇔ 70 12 34₁₆ (3 bytes) |
consume |
Decodes the left codec and then the right codec depending on the left result, then discards the left value and returns only the right | byteAligned(bool).consume[Int](isLarge ⇒ if (isLarge) uint16 else uint8)(_ > 0xff) |
Int |
8 | ∞ | 255 ⇔ 00 ff₁₆ (2 bytes) 256 ⇔ 80 01 00₁₆ (3 bytes) 0x1234 ⇔ 80 12 34₁₆ (3 bytes) |
:: |
Concat two codecs into an HList | uint8 :: cstring |
Int :: String :: HNil |
8 | ∞ | 0x42 :: "zweiundvierzig" :: HNil ⇔ 42 7a 77 65 69 75 6e 64 76 69 65 72 7a 69 67 00₁₆ (16 bytes) |
dropUnits |
Remove Unit elements from an HList codec | constant(hex"ca fe") :: cstring).dropUnits |
String :: HNil |
16 | ∞ | "dreiundzwanzig" :: HNil ⇔ ca fe 64 72 65 69 75 6e 64 7a 77 61 6e 7a 69 67 00₁₆ (17 bytes) |
:~>: |
Concat two codecs discarding the Unit value of the left one | constant(hex"ab cd ef") :~>: uint16 :: uint8 |
Int :: Int :: HNil |
48 | 48 | 0x1234 :: 0x23 :: HNil ⇔ ab cd ef 12 34 23₁₆ (6 bytes) |
:+ |
Append to left HList codec the right codec. | uint8.hlist :+ uint16 |
Int :: Int :: HNil |
24 | 24 | 0x42 :: 0xcdef :: HNil ⇔ 42 cd ef₁₆ (3 bytes) |
::: |
Concat two HList codecs | (uint8 :: cstring) ::: (constant(0x23) :: uint16) |
Int :: String :: Unit :: Int :: HNil |
32 | ∞ | 0x42 :: "zweiundvierzig" :: () :: 0xabcd :: HNil ⇔ 42 7a 77 65 69 75 6e 64 76 69 65 72 7a 69 67 00 23 ab cd₁₆ (19 bytes) |
flatZipHList |
Concat to HList result of first Codec with result of Codec determined after based on value of first part | uint8 flatZipHList { case strSize ⇒ limitedSizeBytes(strSize, utf8) } |
Int :: String :: HNil |
8 | ∞ | 8 :: "sausages" :: HNil ⇔ 08 73 61 75 73 61 67 65 73₁₆ (9 bytes) |
flatPrepend |
Concat to HList result of first Codec with result of HList Codec determined after based on value of first part | uint8 flatPrepend { case strSize ⇒ limitedSizeBytes(strSize, utf8) :: uint16 } |
Int :: String :: Int :: HNil |
8 | ∞ | 8 :: "sausages" :: 0x1234 :: HNil ⇔ 08 73 61 75 73 61 67 65 73 12 34₁₆ (11 bytes) |
>>:~ |
Concat to HList result of first Codec with result of HList Codec determined after based on value of first part | uint8 >>:~ { case strSize ⇒ limitedSizeBytes(strSize, utf8) :: uint16 } |
Int :: String :: Int :: HNil |
8 | ∞ | 8 :: "sausages" :: 0x1234 :: HNil ⇔ 08 73 61 75 73 61 67 65 73 12 34₁₆ (11 bytes) |
flatAppend |
Concat result of first HList Codec with result of Codec determined after based on value of first part | uint8 :: uint16 flatAppend { case strSize :: _ :: HNil ⇒ limitedSizeBytes(strSize, utf8) } |
Int :: Int :: String :: HNil |
24 | ∞ | 8 :: 0xabcd :: "sausages" :: HNil ⇔ 08 ab cd 73 61 75 73 61 67 65 73₁₆ (11 bytes) |
flatConcat |
Concat result of first HList Codec with result of HList Codec determined after based on value of first part | uint8 :: uint16 flatConcat { case strSize :: _ :: HNil ⇒ limitedSizeBytes(strSize, utf8) :: uint16 } |
Int :: Int :: String :: Int :: HNil |
24 | ∞ | 8 :: 0xabcd :: "sausages" :: 0x1234 :: HNil ⇔ 08 ab cd 73 61 75 73 61 67 65 73 12 34₁₆ (13 bytes) |
- Add or edit meta information in
PrimitiveCodecs.scala,ParameterizedCodecs.scala, orCodecCombinators.scala - Run
sbt "generator/runMain scodec.meta.CheatSheetGenerator"to regenerate the table (the generator will replace all content in this file between lines starting with## Primitive Codecsand## Contributing) - Commit changes + PR
This cheat sheet was original created by Johannes Rudolph. This document and the accompanying source code is freely available under the CC0 license.