# Crate fibonacci_codec[−][src]

Traits and functions for encoding and decoding (slices of) positive integers using Fibonacci Coding.

Fibonacci coding is a method for representing a continuous stream
of (positive) integers using a variable number of bits – e.g.,
instead of taking up 2*32 bits for storing two `u32`

words, these
words will take up however many bits their fibonacci-encoded
representation takes up.

Fibonacci coding yields better results for smaller numbers than
larger ones: The largest 32-bit words can take up to 47 bits, but
to encode the number `1`

, you only need 2 bits.

Fibonacci coding is self-synchronizing: If a single bit is altered, a single number could be decoded as two (or two numbers decoded as one), but the remaining numbers will be read correctly.

## Value range

Fibonacci coding can represent any number that can be expressed as addition of one or more Fibonacci numbers, so any integer greater than 1, up to the range of the given machine integer type. This means that the integer zero can not be encoded.

If you should need to encode `0`

, it is advisable to encode
numbers incremented by one (preventing overflow by upgrading to
the next-biggest integer type, or by not encoding the maximum
value), and to subtract one from the decoded result.
.

# Examples

## Encoding a slice of numbers:

use fibonacci_codec::Encode; let numbers: Vec<u16> = vec![1, 50, 3003]; let encoded = &numbers.fib_encode().unwrap(); // code words: "11" (1), "001001011" (50), "000010010000100011" (3003) // These encoded words take up 4 bytes instead of 6 (3*16 bits)! assert_eq!(encoded.to_bytes(), [0b11001001, 0b01100001, 0b00100001, 0b00011000]);

## Encoding the value zero:

use fibonacci_codec::Encode; let numbers: Vec<u16> = vec![0, 49, 3002]; let adjusted: Vec<u32> = numbers.iter().map(|n| *n as u32 + 1).collect(); let encoded = &adjusted.fib_encode().unwrap(); // code words: "11" (1), "001001011" (50), "000010010000100011" (3003) // These encoded words take up 4 bytes instead of 6 (3*16 bits)! assert_eq!(encoded.to_bytes(), [0b11001001, 0b01100001, 0b00100001, 0b00011000]);

# References:

## Modules

int |

## Structs

ElementEncodeError | Indicates that encoding an iterator failed at an element. |

## Enums

DecodeError | Returned if decoding a number fails. Usually indicates an overflow of the number being decoded. |

EncodeError | Indicates that encoding a number failed. |

## Traits

Encode | Allows encoding enumerations of unsigned integers (> 0) using fibonacci coding. |

EncodeOne | Allows encoding single primitive integers (> 0) using fibonacci coding. |

## Functions

fib_decode_u8 | Returns an iterator that consumes bits ( |

fib_decode_u16 | Returns an iterator that consumes bits ( |

fib_decode_u32 | Returns an iterator that consumes bits ( |

fib_decode_u64 | Returns an iterator that consumes bits ( |