Safe Haskell | Safe-Inferred |
---|---|
Language | Haskell2010 |
Zigzag encoding maps signed integers to unsigned integers so that numbers with a small absolute value (for instance, -1) have a small varint encoded value too. It does this in a way that "zig-zags" back and forth through the positive and negative integers, so that -1 is encoded as 1, 1 is encoded as 2, -2 is encoded as 3, and so on.
zigzag(n) = { 2 * n if 0 <= n { -2 * n - 1 if n < 0
This description was adapted from https:/developers.google.comprotocol-buffersdocsencoding#signed-ints which is released under https://creativecommons.org/licenses/by/4.0/
Synopsis
- toZigzag :: Integer -> Natural
- fromZigzag :: Natural -> Integer
- toZigzagNative :: Int -> Word
- fromZigzagNative :: Word -> Int
- toZigzag32 :: Int32 -> Word32
- fromZigzag32 :: Word32 -> Int32
- toZigzag64 :: Int64 -> Word64
- fromZigzag64 :: Word64 -> Int64
Documentation
toZigzag :: Integer -> Natural Source #
Encode a big integer with zigzag.
If you know the size of the data, it is likely more efficient to use one of
toZigzagNative
, toZigzag32
, or toZigzag64
.
fromZigzag :: Natural -> Integer Source #
Decode a zigzag-encoded big ingeter.
If you know the size of the data, it is likely more efficient to use one of
fromZigzagNative
, fromZigzag32
, or fromZigzag64
.
toZigzagNative :: Int -> Word Source #
Encode a native-size integer with zigzag.
In C, this is:
(n << 1) ^ (n >> (CHAR_BIT * sizeof(int) - 1))
fromZigzagNative :: Word -> Int Source #
Decode a native-size zigzag-encoded integer.
In C, this is:
(n >> 1) ^ (~(n & 1) + 1)
toZigzag32 :: Int32 -> Word32 Source #
Encode a 32-bit integer with zigzag.
In C, this is:
(n << 1) ^ (n >> 31)
fromZigzag32 :: Word32 -> Int32 Source #
Decode a 32-bit zigzag-encoded integer.
In C, this is:
(n >> 1) ^ (~(n & 1) + 1)
toZigzag64 :: Int64 -> Word64 Source #
Encode a 64-bit integer with zigzag.
In C, this is:
(n << 1) ^ (n >> 63)
fromZigzag64 :: Word64 -> Int64 Source #
Decode a 64-bit zigzag-encoded integer.
In C, this is:
(n >> 1) ^ (~(n & 1) + 1)