Rewrite benchmarks not to use indirect calls

Move the important benchmarks back into the xxhash package itself.

Updates #22

bench_test.go

@@ -0,0 +1,74 @@
+package xxhash
+
+import (
+	"strings"
+	"testing"
+)
+
+var benchmarks = []struct {
+	name string
+	n    int64
+}{
+	{"4B", 4},
+	{"100B", 100},
+	{"4KB", 4e3},
+	{"10MB", 10e6},
+}
+
+func BenchmarkSum64(b *testing.B) {
+	for _, bb := range benchmarks {
+		in := make([]byte, bb.n)
+		for i := range in {
+			in[i] = byte(i)
+		}
+		b.Run(bb.name, func(b *testing.B) {
+			b.SetBytes(bb.n)
+			for i := 0; i < b.N; i++ {
+				_ = Sum64(in)
+			}
+		})
+	}
+}
+
+func BenchmarkSum64String(b *testing.B) {
+	for _, bb := range benchmarks {
+		s := strings.Repeat("a", int(bb.n))
+		b.Run(bb.name, func(b *testing.B) {
+			b.SetBytes(bb.n)
+			for i := 0; i < b.N; i++ {
+				_ = Sum64String(s)
+			}
+		})
+	}
+}
+
+func BenchmarkDigestBytes(b *testing.B) {
+	for _, bb := range benchmarks {
+		in := make([]byte, bb.n)
+		for i := range in {
+			in[i] = byte(i)
+		}
+		b.Run(bb.name, func(b *testing.B) {
+			b.SetBytes(bb.n)
+			for i := 0; i < b.N; i++ {
+				h := New()
+				h.Write(in)
+				_ = h.Sum64()
+			}
+		})
+	}
+}
+
+func BenchmarkDigestString(b *testing.B) {
+	for _, bb := range benchmarks {
+		s := strings.Repeat("a", int(bb.n))
+		b.Run(bb.name, func(b *testing.B) {
+			b.SetBytes(bb.n)
+			for i := 0; i < b.N; i++ {
+				h := New()
+				h.WriteString(s)
+				_ = h.Sum64()
+			}
+		})
+	}
+}

xxhashbench/xxhashbench_test.go

@@ -11,6 +11,10 @@ import (
 	"github.com/spaolacci/murmur3"
 )
 
+// TODO: The main benchmarks live in the xxhash package now, so the only purpose
+// of this is to compare different hash functions. Consider deleting xxhashbench
+// or replacing it with a more minimal comparison.
+
 var sink uint64
 
 var benchmarks = []struct {