From 657978b416909f48dac5b5109a5b2f8f2913b127 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Sat, 17 Jan 2026 11:38:29 -1000
Subject: [PATCH] [core] Add fnv1_hash_extend() string overloads, use in
 atm90e32

---
 esphome/components/atm90e32/atm90e32.cpp |  9 ++++++---
 esphome/core/helpers.h                   | 20 ++++++++++++++++++++
 2 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/esphome/components/atm90e32/atm90e32.cpp b/esphome/components/atm90e32/atm90e32.cpp
index 634260b5e9..f4c199cb98 100644
--- a/esphome/components/atm90e32/atm90e32.cpp
+++ b/esphome/components/atm90e32/atm90e32.cpp
@@ -158,12 +158,14 @@ void ATM90E32Component::setup() {
 
   if (this->enable_offset_calibration_) {
     // Initialize flash storage for offset calibrations
-    uint32_t o_hash = fnv1_hash(std::string("_offset_calibration_") + this->cs_summary_);
+    uint32_t o_hash = fnv1_hash("_offset_calibration_");
+    o_hash = fnv1_hash_extend(o_hash, this->cs_summary_);
     this->offset_pref_ = global_preferences->make_preference<OffsetCalibration[3]>(o_hash, true);
     this->restore_offset_calibrations_();
 
     // Initialize flash storage for power offset calibrations
-    uint32_t po_hash = fnv1_hash(std::string("_power_offset_calibration_") + this->cs_summary_);
+    uint32_t po_hash = fnv1_hash("_power_offset_calibration_");
+    po_hash = fnv1_hash_extend(po_hash, this->cs_summary_);
     this->power_offset_pref_ = global_preferences->make_preference<PowerOffsetCalibration[3]>(po_hash, true);
     this->restore_power_offset_calibrations_();
   } else {
@@ -183,7 +185,8 @@ void ATM90E32Component::setup() {
 
   if (this->enable_gain_calibration_) {
     // Initialize flash storage for gain calibration
-    uint32_t g_hash = fnv1_hash(std::string("_gain_calibration_") + this->cs_summary_);
+    uint32_t g_hash = fnv1_hash("_gain_calibration_");
+    g_hash = fnv1_hash_extend(g_hash, this->cs_summary_);
     this->gain_calibration_pref_ = global_preferences->make_preference<GainCalibration[3]>(g_hash, true);
     this->restore_gain_calibrations_();
 
diff --git a/esphome/core/helpers.h b/esphome/core/helpers.h
index 409c691cb1..d08b52190c 100644
--- a/esphome/core/helpers.h
+++ b/esphome/core/helpers.h
@@ -395,6 +395,26 @@ constexpr uint32_t FNV1_OFFSET_BASIS = 2166136261UL;
 /// FNV-1 32-bit prime
 constexpr uint32_t FNV1_PRIME = 16777619UL;
 
+/// Extend a FNV-1 hash with an integer (hashes each byte).
+template<std::integral T> constexpr uint32_t fnv1_hash_extend(uint32_t hash, T value) {
+  for (size_t i = 0; i < sizeof(T); i++) {
+    hash *= FNV1_PRIME;
+    hash ^= (value >> (i * 8)) & 0xFF;
+  }
+  return hash;
+}
+/// Extend a FNV-1 hash with additional string data.
+constexpr uint32_t fnv1_hash_extend(uint32_t hash, const char *str) {
+  if (str) {
+    while (*str) {
+      hash *= FNV1_PRIME;
+      hash ^= *str++;
+    }
+  }
+  return hash;
+}
+inline uint32_t fnv1_hash_extend(uint32_t hash, const std::string &str) { return fnv1_hash_extend(hash, str.c_str()); }
+
 /// Extend a FNV-1a hash with additional string data.
 constexpr uint32_t fnv1a_hash_extend(uint32_t hash, const char *str) {
   if (str) {