From 5b92d0b89e1e6a6b4cb87c8bdeaeb5a1adb4bdc8 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Sun, 18 Jan 2026 18:37:14 -1000
Subject: [PATCH] [wiegand] Replace heap-allocating to_string with stack
 buffers (#13294)

---
 esphome/components/wiegand/wiegand.cpp | 22 +++++++++++++---------
 1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/esphome/components/wiegand/wiegand.cpp b/esphome/components/wiegand/wiegand.cpp
index dd1443d10c..f3f578794a 100644
--- a/esphome/components/wiegand/wiegand.cpp
+++ b/esphome/components/wiegand/wiegand.cpp
@@ -1,4 +1,5 @@
 #include "wiegand.h"
+#include <cinttypes>
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 
@@ -69,32 +70,35 @@ void Wiegand::loop() {
   for (auto *trigger : this->raw_triggers_)
     trigger->trigger(count, value);
   if (count == 26) {
-    std::string tag = to_string((value >> 1) & 0xffffff);
-    ESP_LOGD(TAG, "received 26-bit tag: %s", tag.c_str());
+    char tag_buf[12];  // max 8 digits for 24-bit value + null
+    buf_append_printf(tag_buf, sizeof(tag_buf), 0, "%" PRIu32, static_cast<uint32_t>((value >> 1) & 0xffffff));
+    ESP_LOGD(TAG, "received 26-bit tag: %s", tag_buf);
     if (!check_eparity(value, 13, 13) || !check_oparity(value, 0, 13)) {
       ESP_LOGW(TAG, "invalid parity");
       return;
     }
     for (auto *trigger : this->tag_triggers_)
-      trigger->trigger(tag);
+      trigger->trigger(tag_buf);
   } else if (count == 34) {
-    std::string tag = to_string((value >> 1) & 0xffffffff);
-    ESP_LOGD(TAG, "received 34-bit tag: %s", tag.c_str());
+    char tag_buf[12];  // max 10 digits for 32-bit value + null
+    buf_append_printf(tag_buf, sizeof(tag_buf), 0, "%" PRIu32, static_cast<uint32_t>((value >> 1) & 0xffffffff));
+    ESP_LOGD(TAG, "received 34-bit tag: %s", tag_buf);
     if (!check_eparity(value, 17, 17) || !check_oparity(value, 0, 17)) {
       ESP_LOGW(TAG, "invalid parity");
       return;
     }
     for (auto *trigger : this->tag_triggers_)
-      trigger->trigger(tag);
+      trigger->trigger(tag_buf);
   } else if (count == 37) {
-    std::string tag = to_string((value >> 1) & 0x7ffffffff);
-    ESP_LOGD(TAG, "received 37-bit tag: %s", tag.c_str());
+    char tag_buf[12];  // max 11 digits for 35-bit value + null
+    buf_append_printf(tag_buf, sizeof(tag_buf), 0, "%" PRIu64, static_cast<uint64_t>((value >> 1) & 0x7ffffffff));
+    ESP_LOGD(TAG, "received 37-bit tag: %s", tag_buf);
     if (!check_eparity(value, 18, 19) || !check_oparity(value, 0, 19)) {
       ESP_LOGW(TAG, "invalid parity");
       return;
     }
     for (auto *trigger : this->tag_triggers_)
-      trigger->trigger(tag);
+      trigger->trigger(tag_buf);
   } else if (count == 4) {
     for (auto *trigger : this->key_triggers_)
       trigger->trigger(value);