Start primes at 0

xxhash.go

@@ -20,7 +20,7 @@ const (
 //
 // The consts are used when possible in Go code to avoid MOVs but we need a
 // contiguous array of the assembly code.
-var primes = [...]uint64{0, prime1, prime2, prime3, prime4, prime5}
+var primes = [...]uint64{prime1, prime2, prime3, prime4, prime5}
 
 // Digest implements hash.Hash64.
 type Digest struct {
@@ -42,10 +42,10 @@ func New() *Digest {
 
 // Reset clears the Digest's state so that it can be reused.
 func (d *Digest) Reset() {
-	d.v1 = primes[1] + prime2
+	d.v1 = primes[0] + prime2
 	d.v2 = prime2
 	d.v3 = 0
-	d.v4 = -primes[1]
+	d.v4 = -primes[0]
 	d.total = 0
 	d.n = 0
 }

xxhash_amd64.s

@@ -71,17 +71,17 @@ loop:  \
 #define do1() \
 	MOVBQZX (p), tmp            \
 	ADDQ    $1, p               \
-	IMULQ   ·primes+40(SB), tmp \
+	IMULQ   ·primes+32(SB), tmp \
 	XORQ    tmp, h              \
 	ROLQ    $11, h              \
 	IMULQ   prime1, h           \
 
 // func Sum64(b []byte) uint64
 TEXT ·Sum64(SB), NOSPLIT|NOFRAME, $0-32
 	// Load fixed primes.
-	MOVQ ·primes+8(SB), prime1
-	MOVQ ·primes+16(SB), prime2
-	MOVQ ·primes+32(SB), prime4
+	MOVQ ·primes+0(SB), prime1
+	MOVQ ·primes+8(SB), prime2
+	MOVQ ·primes+24(SB), prime4
 
 	// Load slice.
 	MOVQ b_base+0(FP), p
@@ -125,7 +125,7 @@ TEXT ·Sum64(SB), NOSPLIT|NOFRAME, $0-32
 	JMP afterBlocks
 
 noBlocks:
-	MOVQ ·primes+40(SB), h
+	MOVQ ·primes+32(SB), h
 
 afterBlocks:
 	ADDQ n, h
@@ -156,7 +156,7 @@ try4:
 
 	ROLQ  $23, h
 	IMULQ prime2, h
-	ADDQ  ·primes+24(SB), h
+	ADDQ  ·primes+16(SB), h
 
 try2:
 	ADDQ $2, end
@@ -181,7 +181,7 @@ finalize:
 	MOVQ  h, tmp
 	SHRQ  $29, tmp
 	XORQ  tmp, h
-	IMULQ ·primes+24(SB), h
+	IMULQ ·primes+16(SB), h
 	MOVQ  h, tmp
 	SHRQ  $32, tmp
 	XORQ  tmp, h
@@ -195,8 +195,8 @@ finalize:
 // func writeBlocks(d *Digest, b []byte) int
 TEXT ·writeBlocks(SB), NOSPLIT|NOFRAME, $0-40
 	// Load fixed primes needed for round.
-	MOVQ ·primes+8(SB), prime1
-	MOVQ ·primes+16(SB), prime2
+	MOVQ ·primes+0(SB), prime1
+	MOVQ ·primes+8(SB), prime2
 
 	// Load slice.
 	MOVQ b_base+8(FP), p

xxhash_arm64.s

@@ -60,9 +60,9 @@
 TEXT ·Sum64(SB), NOSPLIT|NOFRAME, $0-32
 	LDP b_base+0(FP), (p, n)
 
-	LDP  ·primes+8(SB), (prime1, prime2)
-	LDP  ·primes+24(SB), (prime3, prime4)
-	MOVD ·primes+40(SB), prime5
+	LDP  ·primes+0(SB), (prime1, prime2)
+	LDP  ·primes+16(SB), (prime3, prime4)
+	MOVD ·primes+32(SB), prime5
 
 	CMP  $32, n
 	CSEL LT, prime5, ZR, h // if n < 32 { h = prime5 } else { h = 0 }
@@ -162,7 +162,7 @@ finalize:
 
 // func writeBlocks(d *Digest, b []byte) int
 TEXT ·writeBlocks(SB), NOSPLIT|NOFRAME, $0-40
-	LDP ·primes+8(SB), (prime1, prime2)
+	LDP ·primes+0(SB), (prime1, prime2)
 
 	// Load state. Assume v[1-4] are stored contiguously.
 	MOVD d+0(FP), digest

xxhash_other.go

@@ -15,10 +15,10 @@ func Sum64(b []byte) uint64 {
 	var h uint64
 
 	if n >= 32 {
-		v1 := primes[1] + prime2
+		v1 := primes[0] + prime2
 		v2 := prime2
 		v3 := uint64(0)
-		v4 := -primes[1]
+		v4 := -primes[0]
 		for len(b) >= 32 {
 			v1 = round(v1, u64(b[0:8:len(b)]))
 			v2 = round(v2, u64(b[8:16:len(b)]))