Add FNV-1a hash functions (#12502)

esphome/core/helpers.cpp

@@ -143,17 +143,29 @@ uint16_t crc16be(const uint8_t *data, uint16_t len, uint16_t crc, uint16_t poly,
   return refout ? (crc ^ 0xffff) : crc;
 }
 
+// FNV-1 hash - deprecated, use fnv1a_hash() for new code
 uint32_t fnv1_hash(const char *str) {
-  uint32_t hash = 2166136261UL;
+  uint32_t hash = FNV1_OFFSET_BASIS;
   if (str) {
     while (*str) {
-      hash *= 16777619UL;
+      hash *= FNV1_PRIME;
       hash ^= *str++;
     }
   }
   return hash;
 }
 
+// FNV-1a hash - preferred for new code
+uint32_t fnv1a_hash_extend(uint32_t hash, const char *str) {
+  if (str) {
+    while (*str) {
+      hash ^= *str++;
+      hash *= FNV1_PRIME;
+    }
+  }
+  return hash;
+}
+
 float random_float() { return static_cast<float>(random_uint32()) / static_cast<float>(UINT32_MAX); }
 
 // Strings