1 files changed, 4 insertions, 64 deletions

diff --git a/src/bytes/bytes.go b/src/bytes/bytes.go
index e872cc2050..e7931387aa 100644
--- a/src/bytes/bytes.go
+++ b/src/bytes/bytes.go
@@ -117,17 +117,17 @@ func LastIndex(s, sep []byte) int {
 		return -1
 	}
 	// Rabin-Karp search from the end of the string
-	hashss, pow := hashStrRev(sep)
+	hashss, pow := bytealg.HashStrRevBytes(sep)
 	last := len(s) - n
 	var h uint32
 	for i := len(s) - 1; i >= last; i-- {
-		h = h*primeRK + uint32(s[i])
+		h = h*bytealg.PrimeRK + uint32(s[i])
 	}
 	if h == hashss && Equal(s[last:], sep) {
 		return last
 	}
 	for i := last - 1; i >= 0; i-- {
-		h *= primeRK
+		h *= bytealg.PrimeRK
 		h += uint32(s[i])
 		h -= pow * uint32(s[i+n])
 		if h == hashss && Equal(s[i:i+n], sep) {
@@ -1068,7 +1068,7 @@ func Index(s, sep []byte) int {
 			// we should cutover at even larger average skips,
 			// because Equal becomes that much more expensive.
 			// This code does not take that effect into account.
-			j := indexRabinKarp(s[i:], sep)
+			j := bytealg.IndexRabinKarpBytes(s[i:], sep)
 			if j < 0 {
 				return -1
 			}
@@ -1077,63 +1077,3 @@ func Index(s, sep []byte) int {
 	}
 	return -1
 }
-
-func indexRabinKarp(s, sep []byte) int {
-	// Rabin-Karp search
-	hashsep, pow := hashStr(sep)
-	n := len(sep)
-	var h uint32
-	for i := 0; i < n; i++ {
-		h = h*primeRK + uint32(s[i])
-	}
-	if h == hashsep && Equal(s[:n], sep) {
-		return 0
-	}
-	for i := n; i < len(s); {
-		h *= primeRK
-		h += uint32(s[i])
-		h -= pow * uint32(s[i-n])
-		i++
-		if h == hashsep && Equal(s[i-n:i], sep) {
-			return i - n
-		}
-	}
-	return -1
-}
-
-// primeRK is the prime base used in Rabin-Karp algorithm.
-const primeRK = 16777619
-
-// hashStr returns the hash and the appropriate multiplicative
-// factor for use in Rabin-Karp algorithm.
-func hashStr(sep []byte) (uint32, uint32) {
-	hash := uint32(0)
-	for i := 0; i < len(sep); i++ {
-		hash = hash*primeRK + uint32(sep[i])
-	}
-	var pow, sq uint32 = 1, primeRK
-	for i := len(sep); i > 0; i >>= 1 {
-		if i&1 != 0 {
-			pow *= sq
-		}
-		sq *= sq
-	}
-	return hash, pow
-}
-
-// hashStrRev returns the hash of the reverse of sep and the
-// appropriate multiplicative factor for use in Rabin-Karp algorithm.
-func hashStrRev(sep []byte) (uint32, uint32) {
-	hash := uint32(0)
-	for i := len(sep) - 1; i >= 0; i-- {
-		hash = hash*primeRK + uint32(sep[i])
-	}
-	var pow, sq uint32 = 1, primeRK
-	for i := len(sep); i > 0; i >>= 1 {
-		if i&1 != 0 {
-			pow *= sq
-		}
-		sq *= sq
-	}
-	return hash, pow
-}