net: efficient text processing
Optimize IP.String, IPMask.String and ParseIP.
benchmark old ns/op new ns/op delta
BenchmarkParseIP 2216 1849 -16.56%
BenchmarkIPString 7828 2486 -68.24%
BenchmarkIPMaskString 3872 659 -82.98%
LGTM=mikioh.mikioh, dave, bradfitz
R=golang-codereviews, mikioh.mikioh, dave, bradfitz
CC=golang-codereviews
https://golang.org/cl/95750043
diff --git a/src/pkg/net/parse.go b/src/pkg/net/parse.go
index ee6e7e9..e1d0130 100644
--- a/src/pkg/net/parse.go
+++ b/src/pkg/net/parse.go
@@ -210,18 +210,18 @@
return string(b[bp:])
}
-// Convert i to hexadecimal string.
-func itox(i uint, min int) string {
- // Assemble hexadecimal in reverse order.
- var b [32]byte
- bp := len(b)
- for ; i > 0 || min > 0; i /= 16 {
- bp--
- b[bp] = "0123456789abcdef"[byte(i%16)]
- min--
+// Convert i to a hexadecimal string. Leading zeros are not printed.
+func appendHex(dst []byte, i uint32) []byte {
+ if i == 0 {
+ return append(dst, '0')
}
-
- return string(b[bp:])
+ for j := 7; j >= 0; j-- {
+ v := i >> uint(j*4)
+ if v > 0 {
+ dst = append(dst, hexDigit[v&0xf])
+ }
+ }
+ return dst
}
// Number of occurrences of b in s.
