mirror of
https://github.com/metabarcoding/obitools4.git
synced 2026-04-30 12:00:39 +00:00
Eric Coissac
8c7017a99d
- Update obioptions.Version from "Release 4.4.29" to "/v/ Release v5" - Update version.txt from 4.29 → .30 (automated by Makefile)
34 lines
1.5 KiB
Markdown
34 lines
1.5 KiB
Markdown
# Variable-Length Integer Encoding/Decoding Utility
|
||
|
||
This Go package (`obikmer`) provides efficient serialization of `uint64` integers using **protobuf-style variable-length encoding (varint)**.
|
||
|
||
## Core Features
|
||
|
||
- ✅ `EncodeVarint(io.Writer, uint64) (n int, err error)`
|
||
Writes a `uint64` as a compact varint to any `io.Writer`. Uses **7 bits per byte**, with the MSB as a continuation flag. Max 10 bytes for `uint64`.
|
||
|
||
- ✅ `DecodeVarint(io.Reader) (val uint64, err error)`
|
||
Reads and decodes a varint from any `io.Reader`. Handles multi-byte sequences safely; returns error on malformed input or overflow (>70 bits).
|
||
|
||
- ✅ `VarintLen(uint64) int`
|
||
Computes the exact byte length required to encode a value *without* performing I/O — useful for buffer preallocation or size estimation.
|
||
|
||
## Encoding Scheme
|
||
|
||
- Each byte holds 7 bits of data; bit 8 (MSB) = `1` if more bytes follow, else `0`.
|
||
- Example:
|
||
- `0x7F` → `1 byte`: `0111_1111`
|
||
- `0x80` → `2 bytes`: `1000_0000 0000_0001`
|
||
|
||
## Use Cases
|
||
|
||
- Network protocols & binary file formats requiring compact integer representation
|
||
- Serialization frameworks (e.g., custom protobuf-like codecs)
|
||
- Embedded systems or bandwidth-constrained environments where space efficiency matters
|
||
|
||
## Design Notes
|
||
|
||
- No external dependencies; uses only `io` from the standard library.
|
||
- Thread-safe *per call* (no shared state), but `io.Reader`/`Writer` concurrency must be handled externally.
|
||
- Compatible with standard protobuf varint format (e.g., interoperable with `encoding/binary` or gRPC).
|