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stream_float.go 2.69 KB
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package jsoniter
import (
"fmt"
"math"
"strconv"
)
var pow10 []uint64
func init() {
pow10 = []uint64{1, 10, 100, 1000, 10000, 100000, 1000000}
}
// WriteFloat32 write float32 to stream
func (stream *Stream) WriteFloat32(val float32) {
if math.IsInf(float64(val), 0) || math.IsNaN(float64(val)) {
stream.Error = fmt.Errorf("unsupported value: %f", val)
return
}
abs := math.Abs(float64(val))
fmt := byte('f')
// Note: Must use float32 comparisons for underlying float32 value to get precise cutoffs right.
if abs != 0 {
if float32(abs) < 1e-6 || float32(abs) >= 1e21 {
fmt = 'e'
}
}
stream.buf = strconv.AppendFloat(stream.buf, float64(val), fmt, -1, 32)
}
// WriteFloat32Lossy write float32 to stream with ONLY 6 digits precision although much much faster
func (stream *Stream) WriteFloat32Lossy(val float32) {
if math.IsInf(float64(val), 0) || math.IsNaN(float64(val)) {
stream.Error = fmt.Errorf("unsupported value: %f", val)
return
}
if val < 0 {
stream.writeByte('-')
val = -val
}
if val > 0x4ffffff {
stream.WriteFloat32(val)
return
}
precision := 6
exp := uint64(1000000) // 6
lval := uint64(float64(val)*float64(exp) + 0.5)
stream.WriteUint64(lval / exp)
fval := lval % exp
if fval == 0 {
return
}
stream.writeByte('.')
for p := precision - 1; p > 0 && fval < pow10[p]; p-- {
stream.writeByte('0')
}
stream.WriteUint64(fval)
for stream.buf[len(stream.buf)-1] == '0' {
stream.buf = stream.buf[:len(stream.buf)-1]
}
}
// WriteFloat64 write float64 to stream
func (stream *Stream) WriteFloat64(val float64) {
if math.IsInf(val, 0) || math.IsNaN(val) {
stream.Error = fmt.Errorf("unsupported value: %f", val)
return
}
abs := math.Abs(val)
fmt := byte('f')
// Note: Must use float32 comparisons for underlying float32 value to get precise cutoffs right.
if abs != 0 {
if abs < 1e-6 || abs >= 1e21 {
fmt = 'e'
}
}
stream.buf = strconv.AppendFloat(stream.buf, float64(val), fmt, -1, 64)
}
// WriteFloat64Lossy write float64 to stream with ONLY 6 digits precision although much much faster
func (stream *Stream) WriteFloat64Lossy(val float64) {
if math.IsInf(val, 0) || math.IsNaN(val) {
stream.Error = fmt.Errorf("unsupported value: %f", val)
return
}
if val < 0 {
stream.writeByte('-')
val = -val
}
if val > 0x4ffffff {
stream.WriteFloat64(val)
return
}
precision := 6
exp := uint64(1000000) // 6
lval := uint64(val*float64(exp) + 0.5)
stream.WriteUint64(lval / exp)
fval := lval % exp
if fval == 0 {
return
}
stream.writeByte('.')
for p := precision - 1; p > 0 && fval < pow10[p]; p-- {
stream.writeByte('0')
}
stream.WriteUint64(fval)
for stream.buf[len(stream.buf)-1] == '0' {
stream.buf = stream.buf[:len(stream.buf)-1]
}
}
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