neo-go/pkg/util/fixed8.go
Roman Khimov 54d888ba70 io: add type-specific read/write methods
This seriously improves the serialization/deserialization performance for
several reasons:
 * no time spent in `binary` reflection
 * no memory allocations being made on every read/write
 * uses fast ReadBytes everywhere it's appropriate

It also makes Fixed8 Serializable just for convenience.
2019-12-12 20:19:50 +03:00

165 lines
3.7 KiB
Go

package util
import (
"encoding/json"
"errors"
"strconv"
"strings"
"github.com/CityOfZion/neo-go/pkg/io"
)
const (
precision = 8
decimals = 100000000
)
var errInvalidString = errors.New("fixed8 must satisfy following regex \\d+(\\.\\d{1,8})?")
// Fixed8 represents a fixed-point number with precision 10^-8.
type Fixed8 int64
// String implements the Stringer interface.
func (f Fixed8) String() string {
buf := new(strings.Builder)
val := int64(f)
if val < 0 {
buf.WriteRune('-')
val = -val
}
str := strconv.FormatInt(val/decimals, 10)
buf.WriteString(str)
val %= decimals
if val > 0 {
buf.WriteRune('.')
str = strconv.FormatInt(val, 10)
for i := len(str); i < 8; i++ {
buf.WriteRune('0')
}
buf.WriteString(strings.TrimRight(str, "0"))
}
return buf.String()
}
// FloatValue returns the original value representing Fixed8 as float64.
func (f Fixed8) FloatValue() float64 {
return float64(f) / decimals
}
// Int64Value returns the original value representing Fixed8 as int64.
func (f Fixed8) Int64Value() int64 {
return int64(f) / decimals
}
// Fixed8FromInt64 returns a new Fixed8 type multiplied by decimals.
func Fixed8FromInt64(val int64) Fixed8 {
return Fixed8(decimals * val)
}
// Fixed8FromFloat returns a new Fixed8 type multiplied by decimals.
func Fixed8FromFloat(val float64) Fixed8 {
return Fixed8(int64(decimals * val))
}
// Fixed8FromString parses s which must be a fixed point number
// with precision up to 10^-8
func Fixed8FromString(s string) (Fixed8, error) {
parts := strings.SplitN(s, ".", 2)
ip, err := strconv.ParseInt(parts[0], 10, 64)
if err != nil {
return 0, errInvalidString
} else if len(parts) == 1 {
return Fixed8(ip * decimals), nil
}
fp, err := strconv.ParseInt(parts[1], 10, 64)
if err != nil || fp >= decimals {
return 0, errInvalidString
}
for i := len(parts[1]); i < precision; i++ {
fp *= 10
}
if ip < 0 {
return Fixed8(ip*decimals - fp), nil
}
return Fixed8(ip*decimals + fp), nil
}
// UnmarshalJSON implements the json unmarshaller interface.
func (f *Fixed8) UnmarshalJSON(data []byte) error {
var s string
if err := json.Unmarshal(data, &s); err == nil {
p, err := Fixed8FromString(s)
if err != nil {
return err
}
*f = p
return nil
}
var fl float64
if err := json.Unmarshal(data, &fl); err != nil {
return err
}
*f = Fixed8(decimals * fl)
return nil
}
// MarshalJSON implements the json marshaller interface.
func (f Fixed8) MarshalJSON() ([]byte, error) {
return []byte(`"` + f.String() + `"`), nil
}
// DecodeBinary implements the io.Serializable interface.
func (f *Fixed8) DecodeBinary(r *io.BinReader) {
*f = Fixed8(r.ReadU64LE())
}
// EncodeBinary implements the io.Serializable interface.
func (f *Fixed8) EncodeBinary(w *io.BinWriter) {
w.WriteU64LE(uint64(*f))
}
// Satoshi defines the value of a 'Satoshi'.
func Satoshi() Fixed8 {
return Fixed8(1)
}
// Div implements Fixd8 division operator.
func (f Fixed8) Div(i int64) Fixed8 {
return f / Fixed8FromInt64(i)
}
// Add implements Fixd8 addition operator.
func (f Fixed8) Add(g Fixed8) Fixed8 {
return f + g
}
// Sub implements Fixd8 subtraction operator.
func (f Fixed8) Sub(g Fixed8) Fixed8 {
return f - g
}
// LessThan implements Fixd8 < operator.
func (f Fixed8) LessThan(g Fixed8) bool {
return f < g
}
// GreaterThan implements Fixd8 < operator.
func (f Fixed8) GreaterThan(g Fixed8) bool {
return f > g
}
// Equal implements Fixd8 == operator.
func (f Fixed8) Equal(g Fixed8) bool {
return f == g
}
// CompareTo returns the difference between the f and g.
// difference < 0 implies f < g.
// difference = 0 implies f = g.
// difference > 0 implies f > g.
func (f Fixed8) CompareTo(g Fixed8) int {
return int(f - g)
}