hash.fnv1a: add fnv1a.sum64_bytes and fnv1a.sum32_bytes, add doc comments and tests

vlib/hash/fnv1a/fnv1a.v

@@ -1,5 +1,8 @@
 module fnv1a
 
+// This module implements a FNV-1a hash.
+// (see https://en.wikipedia.org/wiki/Fowler–Noll–Vo_hash_function)
+
 const (
 	fnv64_prime        = u64(1099511628211)
 	fnv64_offset_basis = u64(14695981039346656037)
@@ -7,7 +10,8 @@ const (
 	fnv32_prime        = u32(16777619)
 )
 
-[inline]
+// sum32 returns a fnv1a hash of the string, described by `data`
+[direct_array_access; inline]
 pub fn sum32_string(data string) u32 {
 	mut hash := fnv1a.fnv32_offset_basis
 	for i in 0 .. data.len {
@@ -16,7 +20,9 @@ pub fn sum32_string(data string) u32 {
 	return hash
 }
 
-[inline]
+// sum32 returns a fnv1a hash of the memory block, described by the dynamic
+// byte array `data`.
+[direct_array_access; inline]
 pub fn sum32(data []byte) u32 {
 	mut hash := fnv1a.fnv32_offset_basis
 	for i in 0 .. data.len {
@@ -25,7 +31,19 @@ pub fn sum32(data []byte) u32 {
 	return hash
 }
 
-[inline]
+// sum32_bytes returns a fnv1a hash of `data_len` bytes starting at
+// the address in the given &byte pointer `data`.
+[direct_array_access; inline; unsafe]
+pub fn sum32_bytes(data &byte, data_len int) u32 {
+	mut hash := fnv1a.fnv32_offset_basis
+	for i in 0 .. data_len {
+		hash = unsafe { (hash ^ u32(data[i])) * fnv1a.fnv32_prime }
+	}
+	return hash
+}
+
+// sum64 returns a fnv1a hash of the string, described by `data`
+[direct_array_access; inline]
 pub fn sum64_string(data string) u64 {
 	mut hash := fnv1a.fnv64_offset_basis
 	for i in 0 .. data.len {
@@ -34,7 +52,9 @@ pub fn sum64_string(data string) u64 {
 	return hash
 }
 
-[inline]
+// sum64 returns a fnv1a hash of the memory block, described by the dynamic
+// byte array `data`.
+[direct_array_access; inline]
 pub fn sum64(data []byte) u64 {
 	mut hash := fnv1a.fnv64_offset_basis
 	for i in 0 .. data.len {
@@ -42,3 +62,14 @@ pub fn sum64(data []byte) u64 {
 	}
 	return hash
 }
+
+// sum64_bytes returns a fnv1a hash of `data_len` bytes starting at
+// the address in the given &byte pointer `data`.
+[direct_array_access; inline; unsafe]
+pub fn sum64_bytes(data &byte, data_len int) u64 {
+	mut hash := fnv1a.fnv64_offset_basis
+	for i in 0 .. data_len {
+		hash = unsafe { (hash ^ u64(data[i])) * fnv1a.fnv64_prime }
+	}
+	return hash
+}

vlib/hash/fnv1a/fnv1a_test.v

@@ -1,12 +1,29 @@
 import hash.fnv1a
 
-fn test_fnv1a() {
+fn test_fnv1a_sum32() {
+	$if windows {
+		return
+	}
+	ahash := '10bc2abf'
+	a := 'apple'
+	b := fnv1a.sum32_string(a)
+	c := fnv1a.sum32(a.bytes())
+	d := unsafe { fnv1a.sum32_bytes(a.str, a.len) }
+	assert b.hex() == ahash
+	assert c.hex() == ahash
+	assert d.hex() == ahash
+}
+
+fn test_fnv1a_sum64() {
 	$if windows {
 		return
 	}
 	a := 'apple'
+	ahash := 'f74a62a458befdbf'
 	b := fnv1a.sum64_string(a)
 	c := fnv1a.sum64(a.bytes())
-	assert b.hex() == 'f74a62a458befdbf'
-	assert c.hex() == 'f74a62a458befdbf'
+	d := unsafe { fnv1a.sum64_bytes(a.str, a.len) }
+	assert b.hex() == ahash
+	assert c.hex() == ahash
+	assert d.hex() == ahash
 }