From 69c90ef50d71f6ab65f18721ee8b68627ab2548a Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Wed, 29 Dec 2021 12:03:24 +0200
Subject: [PATCH] hash.fnv1a: add generic fnv1a.sum64_struct/1 and
 fnv1a.sum32_struct/1 + tests

---
 vlib/hash/fnv1a/fnv1a.v      | 24 +++++++++++++++++++++++
 vlib/hash/fnv1a/fnv1a_test.v | 38 ++++++++++++++++++++++++++++++++++++
 2 files changed, 62 insertions(+)

diff --git a/vlib/hash/fnv1a/fnv1a.v b/vlib/hash/fnv1a/fnv1a.v
index 73d0899ac6..ffe1384350 100644
--- a/vlib/hash/fnv1a/fnv1a.v
+++ b/vlib/hash/fnv1a/fnv1a.v
@@ -31,6 +31,18 @@ pub fn sum32(data []byte) u32 {
 	return hash
 }
 
+// sum32_bytes returns a fnv1a hash of the struct `s`.
+[direct_array_access; inline]
+pub fn sum32_struct<T>(s &T) u32 {
+	bp := unsafe { &byte(s) }
+	sz := int(sizeof(T))
+	mut hash := fnv1a.fnv32_offset_basis
+	for i in 0 .. sz {
+		hash = unsafe { (hash ^ u32(bp[i])) * fnv1a.fnv32_prime }
+	}
+	return hash
+}
+
 // 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]
@@ -73,3 +85,15 @@ pub fn sum64_bytes(data &byte, data_len int) u64 {
 	}
 	return hash
 }
+
+// sum64_bytes returns a fnv1a hash of the struct `s`.
+[direct_array_access; inline]
+pub fn sum64_struct<T>(s &T) u64 {
+	bp := unsafe { &byte(s) }
+	sz := int(sizeof(T))
+	mut hash := fnv1a.fnv64_offset_basis
+	for i in 0 .. sz {
+		hash = unsafe { (hash ^ u64(bp[i])) * fnv1a.fnv64_prime }
+	}
+	return hash
+}
diff --git a/vlib/hash/fnv1a/fnv1a_test.v b/vlib/hash/fnv1a/fnv1a_test.v
index 9a979b6737..4c5dc762ac 100644
--- a/vlib/hash/fnv1a/fnv1a_test.v
+++ b/vlib/hash/fnv1a/fnv1a_test.v
@@ -1,5 +1,17 @@
 import hash.fnv1a
 
+struct MyStruct {
+mut:
+	x int
+	y int
+	z int
+}
+
+struct Abc {
+mut:
+	a [5]u64
+}
+
 fn test_fnv1a_sum32() {
 	$if windows {
 		return
@@ -12,6 +24,19 @@ fn test_fnv1a_sum32() {
 	assert b.hex() == ahash
 	assert c.hex() == ahash
 	assert d.hex() == ahash
+	//
+	mut aa := Abc{}
+	x := fnv1a.sum32_struct(aa)
+	aa.a[3] = 5
+	y := fnv1a.sum32_struct(aa)
+	assert x != y
+	mut ms := MyStruct{}
+	xx := fnv1a.sum32_struct(ms)
+	ms.x = 77
+	yy := fnv1a.sum32_struct(ms)
+	assert xx != yy
+	assert x != xx
+	assert y != yy
 }
 
 fn test_fnv1a_sum64() {
@@ -26,4 +51,17 @@ fn test_fnv1a_sum64() {
 	assert b.hex() == ahash
 	assert c.hex() == ahash
 	assert d.hex() == ahash
+	//
+	mut aa := Abc{}
+	x := fnv1a.sum64_struct(aa)
+	aa.a[3] = 5
+	y := fnv1a.sum64_struct(aa)
+	assert x != y
+	mut ms := MyStruct{}
+	xx := fnv1a.sum64_struct(ms)
+	ms.x = 77
+	yy := fnv1a.sum64_struct(ms)
+	assert xx != yy
+	assert x != xx
+	assert y != yy
 }