go/json-iterator
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optimize read int32

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This commit is contained in:
Tao Wen
2017-01-15 22:50:31 +08:00
parent c3c57d61b5
commit 399ee3faaa
4 changed files with 222 additions and 165 deletions
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40
feature_iter_float.go
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@ -6,25 +6,25 @@ import (
"unsafe"
)
var zeroToNineDigits []int8
var floatDigits []int8
const invalidCharForNumber = int8(-1)
const endOfNumber = int8(-2)
const dotInNumber = int8(-3)
const safeToMultiple10 = uint64(0xffffffffffffffff) / 10 - 10
const uint64SafeToMultiple10 = uint64(0xffffffffffffffff) / 10 - 10
func init() {
zeroToNineDigits = make([]int8, 256)
for i := 0; i < len(zeroToNineDigits); i++ {
zeroToNineDigits[i] = invalidCharForNumber
floatDigits = make([]int8, 256)
for i := 0; i < len(floatDigits); i++ {
floatDigits[i] = invalidCharForNumber
}
for i := int8('0'); i < int8('9'); i++ {
zeroToNineDigits[i] = i - int8('0')
for i := int8('0'); i <= int8('9'); i++ {
floatDigits[i] = i - int8('0')
}
zeroToNineDigits[','] = endOfNumber;
zeroToNineDigits[']'] = endOfNumber;
zeroToNineDigits['}'] = endOfNumber;
zeroToNineDigits[' '] = endOfNumber;
zeroToNineDigits['.'] = dotInNumber;
floatDigits[','] = endOfNumber;
floatDigits[']'] = endOfNumber;
floatDigits['}'] = endOfNumber;
floatDigits[' '] = endOfNumber;
floatDigits['.'] = dotInNumber;
}
func (iter *Iterator) ReadFloat32() (ret float32) {
@ -44,7 +44,7 @@ func (iter *Iterator) readPositiveFloat32() (ret float32) {
non_decimal_loop:
for ; i < iter.tail; i++ {
c = iter.buf[i]
ind := zeroToNineDigits[c]
ind := floatDigits[c]
switch ind {
case invalidCharForNumber:
return iter.readFloat32SlowPath()
@ -54,7 +54,7 @@ func (iter *Iterator) readPositiveFloat32() (ret float32) {
case dotInNumber:
break non_decimal_loop
}
if value > safeToMultiple10 {
if value > uint64SafeToMultiple10 {
return iter.readFloat32SlowPath()
}
value = (value << 3) + (value << 1) + uint64(ind); // value = value * 10 + ind;
@ -64,7 +64,7 @@ func (iter *Iterator) readPositiveFloat32() (ret float32) {
decimalPlaces := 0;
for ; i < iter.tail; i++ {
c = iter.buf[i]
ind := zeroToNineDigits[c];
ind := floatDigits[c];
switch ind {
case endOfNumber:
if decimalPlaces > 0 && decimalPlaces < len(POW10) {
@ -79,7 +79,7 @@ func (iter *Iterator) readPositiveFloat32() (ret float32) {
return iter.readFloat32SlowPath()
}
decimalPlaces++
if value > safeToMultiple10 {
if value > uint64SafeToMultiple10 {
return iter.readFloat32SlowPath()
}
value = (value << 3) + (value << 1) + uint64(ind)
@ -135,7 +135,7 @@ func (iter *Iterator) readPositiveFloat64() (ret float64) {
non_decimal_loop:
for ; i < iter.tail; i++ {
c = iter.buf[i]
ind := zeroToNineDigits[c]
ind := floatDigits[c]
switch ind {
case invalidCharForNumber:
return iter.readFloat64SlowPath()
@ -145,7 +145,7 @@ func (iter *Iterator) readPositiveFloat64() (ret float64) {
case dotInNumber:
break non_decimal_loop
}
if value > safeToMultiple10 {
if value > uint64SafeToMultiple10 {
return iter.readFloat64SlowPath()
}
value = (value << 3) + (value << 1) + uint64(ind); // value = value * 10 + ind;
@ -155,7 +155,7 @@ func (iter *Iterator) readPositiveFloat64() (ret float64) {
decimalPlaces := 0;
for ; i < iter.tail; i++ {
c = iter.buf[i]
ind := zeroToNineDigits[c];
ind := floatDigits[c];
switch ind {
case endOfNumber:
if decimalPlaces > 0 && decimalPlaces < len(POW10) {
@ -170,7 +170,7 @@ func (iter *Iterator) readPositiveFloat64() (ret float64) {
return iter.readFloat64SlowPath()
}
decimalPlaces++
if value > safeToMultiple10 {
if value > uint64SafeToMultiple10 {
return iter.readFloat64SlowPath()
}
value = (value << 3) + (value << 1) + uint64(ind)