From 2830c7dab8b510dd520ab608a46d9342cc14b28c Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Wed, 7 Jan 2026 08:27:39 -1000
Subject: [PATCH] [ld2410/ld2412/ld2450] Use index-based select publish_state
 to avoid heap allocations (#13051)

---
 esphome/components/ld2410/ld2410.cpp |  7 +++++--
 esphome/components/ld2412/ld2412.cpp |  7 +++++--
 esphome/components/ld2450/ld2450.cpp | 15 +++++++++------
 esphome/components/ld24xx/ld24xx.h   |  9 +++++++++
 4 files changed, 28 insertions(+), 10 deletions(-)

diff --git a/esphome/components/ld2410/ld2410.cpp b/esphome/components/ld2410/ld2410.cpp
index 5ea47d5084..c9b4333f7e 100644
--- a/esphome/components/ld2410/ld2410.cpp
+++ b/esphome/components/ld2410/ld2410.cpp
@@ -117,6 +117,8 @@ constexpr Uint8ToString OUT_PIN_LEVELS_BY_UINT[] = {
     {OUT_PIN_LEVEL_HIGH, "high"},
 };
 
+constexpr uint32_t BAUD_RATES[] = {9600, 19200, 38400, 57600, 115200, 230400, 256000, 460800};
+
 // Helper functions for lookups
 template<size_t N> uint8_t find_uint8(const StringToUint8 (&arr)[N], const char *str) {
   for (const auto &entry : arr) {
@@ -258,9 +260,10 @@ void LD2410Component::read_all_info() {
   this->query_parameters_();
   this->set_config_mode_(false);
 #ifdef USE_SELECT
-  const auto baud_rate = std::to_string(this->parent_->get_baud_rate());
   if (this->baud_rate_select_ != nullptr) {
-    this->baud_rate_select_->publish_state(baud_rate);
+    if (auto index = ld24xx::find_index(BAUD_RATES, this->parent_->get_baud_rate())) {
+      this->baud_rate_select_->publish_state(*index);
+    }
   }
 #endif
 }
diff --git a/esphome/components/ld2412/ld2412.cpp b/esphome/components/ld2412/ld2412.cpp
index 3d51800065..620ac9886b 100644
--- a/esphome/components/ld2412/ld2412.cpp
+++ b/esphome/components/ld2412/ld2412.cpp
@@ -128,6 +128,8 @@ constexpr Uint8ToString OUT_PIN_LEVELS_BY_UINT[] = {
     {OUT_PIN_LEVEL_HIGH, "high"},
 };
 
+constexpr uint32_t BAUD_RATES[] = {9600, 19200, 38400, 57600, 115200, 230400, 256000, 460800};
+
 // Helper functions for lookups
 template<size_t N> uint8_t find_uint8(const StringToUint8 (&arr)[N], const char *str) {
   for (const auto &entry : arr) {
@@ -293,9 +295,10 @@ void LD2412Component::read_all_info() {
 #endif
   this->set_config_mode_(false);
 #ifdef USE_SELECT
-  const auto baud_rate = std::to_string(this->parent_->get_baud_rate());
   if (this->baud_rate_select_ != nullptr) {
-    this->baud_rate_select_->publish_state(baud_rate);
+    if (auto index = ld24xx::find_index(BAUD_RATES, this->parent_->get_baud_rate())) {
+      this->baud_rate_select_->publish_state(*index);
+    }
   }
 #endif
 }
diff --git a/esphome/components/ld2450/ld2450.cpp b/esphome/components/ld2450/ld2450.cpp
index 2c137c3578..3b85694bc0 100644
--- a/esphome/components/ld2450/ld2450.cpp
+++ b/esphome/components/ld2450/ld2450.cpp
@@ -88,6 +88,9 @@ constexpr StringToUint8 ZONE_TYPE_BY_STR[] = {
     {"Filter", ZONE_FILTER},
 };
 
+// Baud rates in the same order as BAUD_RATES_BY_STR for index-based lookup
+constexpr uint32_t BAUD_RATES[] = {9600, 19200, 38400, 57600, 115200, 230400, 256000, 460800};
+
 // Helper functions for lookups
 template<size_t N> uint8_t find_uint8(const StringToUint8 (&arr)[N], const std::string &str) {
   for (const auto &entry : arr) {
@@ -376,9 +379,10 @@ void LD2450Component::read_all_info() {
   this->query_zone_();
   this->set_config_mode_(false);
 #ifdef USE_SELECT
-  const auto baud_rate = std::to_string(this->parent_->get_baud_rate());
-  if (this->baud_rate_select_ != nullptr && strcmp(this->baud_rate_select_->current_option(), baud_rate.c_str()) != 0) {
-    this->baud_rate_select_->publish_state(baud_rate);
+  if (this->baud_rate_select_ != nullptr) {
+    if (auto index = ld24xx::find_index(BAUD_RATES, this->parent_->get_baud_rate())) {
+      this->baud_rate_select_->publish_state(*index);
+    }
   }
   this->publish_zone_type();
 #endif
@@ -710,7 +714,7 @@ bool LD2450Component::handle_ack_data_() {
 
     case CMD_QUERY_ZONE:
       ESP_LOGV(TAG, "Query zone conf");
-      this->zone_type_ = std::stoi(std::to_string(this->buffer_data_[10]), nullptr, 16);
+      this->zone_type_ = this->buffer_data_[10];
       this->publish_zone_type();
 #ifdef USE_SELECT
       if (this->zone_type_select_ != nullptr) {
@@ -812,9 +816,8 @@ void LD2450Component::set_zone_type(const char *state) {
 // Publish Zone Type to Select component
 void LD2450Component::publish_zone_type() {
 #ifdef USE_SELECT
-  std::string zone_type = find_str(ZONE_TYPE_BY_UINT, this->zone_type_);
   if (this->zone_type_select_ != nullptr) {
-    this->zone_type_select_->publish_state(zone_type);
+    this->zone_type_select_->publish_state(find_str(ZONE_TYPE_BY_UINT, this->zone_type_));
   }
 #endif
 }
diff --git a/esphome/components/ld24xx/ld24xx.h b/esphome/components/ld24xx/ld24xx.h
index cbd86e4e40..fd55167974 100644
--- a/esphome/components/ld24xx/ld24xx.h
+++ b/esphome/components/ld24xx/ld24xx.h
@@ -39,6 +39,15 @@
 
 namespace esphome::ld24xx {
 
+// Helper to find index of value in constexpr array
+template<size_t N> optional<size_t> find_index(const uint32_t (&arr)[N], uint32_t value) {
+  for (size_t i = 0; i < N; i++) {
+    if (arr[i] == value)
+      return i;
+  }
+  return {};
+}
+
 static const char *const UNKNOWN_MAC = "unknown";
 static const char *const VERSION_FMT = "%u.%02X.%02X%02X%02X%02X";