vlq

Documentation

Overview

Package vlq provides variable-length encoding for numbers (including integers and floating-point numbers) based on the variable-length quantity (VLQ), with additional offsets to eliminate redundancy.

For better performance, all functions in this package are unsafe for concurrency unless otherwise specified.

Index

• Variables
• func AppendEncodeFloat64(dst []byte, f float64) []byte
• func AppendEncodeInt64(dst []byte, i int64) []byte
• func AppendEncodeUint64(dst []byte, u uint64) []byte
• func DecodeFloat64(src []byte) (f float64, n int, err error)
• func DecodeInt64(src []byte) (i int64, n int, err error)
• func DecodeUint64(src []byte) (u uint64, n int, err error)
• func EncodeFloat64(dst []byte, f float64) int
• func EncodeInt64(dst []byte, i int64) int
• func EncodeUint64(dst []byte, u uint64) int
• func Float64EncodedLen(f float64) int
• func Int64EncodedLen(i int64) int
• func Uint64EncodedLen(u uint64) int

Variables

var ErrSrcIncomplete = errors.AutoNewCustom(
	"src is incomplete",
	errors.PrependFullPkgName,
	0,
)

ErrSrcIncomplete is an error indicating that the source bytes src is incomplete to be decoded with the variable-length quantity (VLQ) style encoding.

The client should use errors.Is to test whether an error is ErrSrcIncomplete.

var ErrSrcTooLarge = errors.AutoNewCustom(
	"src is too large to be decoded into a 64-bit number",
	errors.PrependFullPkgName,
	0,
)

ErrSrcTooLarge is an error indicating that the source bytes src is too large to be decoded into a 64-bit number with the variable-length quantity (VLQ) style encoding.

The client should use errors.Is to test whether an error is ErrSrcTooLarge.

Functions

func AppendEncodeFloat64

func AppendEncodeFloat64(dst []byte, f float64) []byte

AppendEncodeFloat64 appends the variable-length quantity (VLQ) style encoding of the 64-bit floating-point number f to dst and returns the extended byte slice. It converts f to a 64-bit unsigned integer. The integer is then byte-reversed and encoded as a regular unsigned integer.

func AppendEncodeInt64

func AppendEncodeInt64(dst []byte, i int64) []byte

AppendEncodeInt64 appends the variable-length quantity (VLQ) style encoding of the 64-bit signed integer i with zigzag encoding to dst and returns the extended byte slice.

func AppendEncodeUint64

func AppendEncodeUint64(dst []byte, u uint64) []byte

AppendEncodeUint64 appends the variable-length quantity (VLQ) style encoding of the 64-bit unsigned integer u to dst and returns the extended byte slice.

func DecodeFloat64

func DecodeFloat64(src []byte) (f float64, n int, err error)

DecodeFloat64 decodes src into a 64-bit floating-point number with variable-length quantity (VLQ) style encoding. It first decodes src into a 64-bit unsigned integer. The integer is then byte-reversed and converted to a 64-bit floating-point number.

If src is nil or empty, it reports ErrSrcIncomplete.

The decoding stops when obtaining a 64-bit floating-point number. Subsequent content in src (if any) is ignored.

It also returns the number of bytes read from src (n). If err is nil, n is exactly Float64EncodedLen(f). If err is not nil, n is 0.

func DecodeInt64

func DecodeInt64(src []byte) (i int64, n int, err error)

DecodeInt64 decodes src into a 64-bit signed integer with variable-length quantity (VLQ) style encoding and zigzag encoding.

If src is nil or empty, it reports ErrSrcIncomplete.

The decoding stops when obtaining a 64-bit signed integer. Subsequent content in src (if any) is ignored.

It also returns the number of bytes read from src (n). If err is nil, n is exactly Int64EncodedLen(i). If err is not nil, n is 0.

func DecodeUint64

func DecodeUint64(src []byte) (u uint64, n int, err error)

DecodeUint64 decodes src into a 64-bit unsigned integer with variable-length quantity (VLQ) style encoding.

If src is nil or empty, it reports ErrSrcIncomplete.

The decoding stops when obtaining a 64-bit unsigned integer. Subsequent content in src (if any) is ignored.

It also returns the number of bytes read from src (n). If err is nil, n is exactly Uint64EncodedLen(u). If err is not nil, n is 0.

func EncodeFloat64

func EncodeFloat64(dst []byte, f float64) int

EncodeFloat64 encodes the 64-bit floating-point number f in variable-length quantity (VLQ) style encoding. It converts f to a 64-bit unsigned integer. The integer is then byte-reversed and encoded as a regular unsigned integer.

It panics if dst doesn't have enough space to hold the encoding result. The client should guarantee that len(dst) >= Float64EncodedLen(i).

It returns the number of bytes written into dst, exactly Float64EncodedLen(i).

func EncodeInt64

func EncodeInt64(dst []byte, i int64) int

EncodeInt64 encodes the 64-bit signed integer i in variable-length quantity (VLQ) style encoding with zigzag encoding to dst.

It panics if dst doesn't have enough space to hold the encoding result. The client should guarantee that len(dst) >= Int64EncodedLen(i).

It returns the number of bytes written into dst, exactly Int64EncodedLen(i).

func EncodeUint64

func EncodeUint64(dst []byte, u uint64) int

EncodeUint64 encodes the 64-bit unsigned integer u in variable-length quantity (VLQ) style encoding to dst.

It panics if dst doesn't have enough space to hold the encoding result. The client should guarantee that len(dst) >= Uint64EncodedLen(u).

It returns the number of bytes written into dst, exactly Uint64EncodedLen(u).

func Float64EncodedLen

func Float64EncodedLen(f float64) int

Float64EncodedLen returns the length of variable-length quantity (VLQ) style encoding of the corresponding byte-reversed 64-bit unsigned integer of the 64-bit floating-point number f.

It is at most 10.

func Int64EncodedLen

func Int64EncodedLen(i int64) int

Int64EncodedLen returns the length of variable-length quantity (VLQ) style encoding with zigzag encoding of the 64-bit signed integer i.

It is at most 10.

func Uint64EncodedLen

func Uint64EncodedLen(u uint64) int

Uint64EncodedLen returns the length of variable-length quantity (VLQ) style encoding of the 64-bit unsigned integer u.

It is at most 10.