From 38850a9ab35273fe09875c81d9e82c47b8ec7789 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Sat, 27 Dec 2025 15:08:44 -1000
Subject: [PATCH] more dry

---
 esphome/core/helpers.cpp | 45 +++++++++++++++++++---------------------
 esphome/core/helpers.h   |  8 ++++---
 2 files changed, 26 insertions(+), 27 deletions(-)

diff --git a/esphome/core/helpers.cpp b/esphome/core/helpers.cpp
index 66e1fe15122..1c68f1a021c 100644
--- a/esphome/core/helpers.cpp
+++ b/esphome/core/helpers.cpp
@@ -286,28 +286,9 @@ std::string format_mac_address_pretty(const uint8_t *mac) {
   return std::string(buf);
 }
 
-char *format_hex_to(char *buffer, size_t buffer_size, const uint8_t *data, size_t length) {
-  size_t max_bytes = (buffer_size - 1) / 2;
-  if (length > max_bytes) {
-    length = max_bytes;
-  }
-  for (size_t i = 0; i < length; i++) {
-    buffer[2 * i] = format_hex_char(data[i] >> 4);
-    buffer[2 * i + 1] = format_hex_char(data[i] & 0x0F);
-  }
-  buffer[length * 2] = '\0';
-  return buffer;
-}
-
-std::string format_hex(const uint8_t *data, size_t length) {
-  std::string ret;
-  ret.resize(length * 2);
-  format_hex_to(&ret[0], length * 2 + 1, data, length);
-  return ret;
-}
-std::string format_hex(const std::vector<uint8_t> &data) { return format_hex(data.data(), data.size()); }
-
-char *format_hex_pretty_to(char *buffer, size_t buffer_size, const uint8_t *data, size_t length, char separator) {
+// Internal helper for hex formatting - base is 'a' for lowercase or 'A' for uppercase
+static char *format_hex_internal(char *buffer, size_t buffer_size, const uint8_t *data, size_t length, char separator,
+                                 char base) {
   if (length == 0) {
     buffer[0] = '\0';
     return buffer;
@@ -325,8 +306,8 @@ char *format_hex_pretty_to(char *buffer, size_t buffer_size, const uint8_t *data
   }
   for (size_t i = 0; i < length; i++) {
     size_t pos = i * stride;
-    buffer[pos] = format_hex_pretty_char(data[i] >> 4);
-    buffer[pos + 1] = format_hex_pretty_char(data[i] & 0x0F);
+    buffer[pos] = format_hex_char(data[i] >> 4, base);
+    buffer[pos + 1] = format_hex_char(data[i] & 0x0F, base);
     if (separator && i < length - 1) {
       buffer[pos + 2] = separator;
     }
@@ -335,6 +316,22 @@ char *format_hex_pretty_to(char *buffer, size_t buffer_size, const uint8_t *data
   return buffer;
 }
 
+char *format_hex_to(char *buffer, size_t buffer_size, const uint8_t *data, size_t length) {
+  return format_hex_internal(buffer, buffer_size, data, length, 0, 'a');
+}
+
+std::string format_hex(const uint8_t *data, size_t length) {
+  std::string ret;
+  ret.resize(length * 2);
+  format_hex_to(&ret[0], length * 2 + 1, data, length);
+  return ret;
+}
+std::string format_hex(const std::vector<uint8_t> &data) { return format_hex(data.data(), data.size()); }
+
+char *format_hex_pretty_to(char *buffer, size_t buffer_size, const uint8_t *data, size_t length, char separator) {
+  return format_hex_internal(buffer, buffer_size, data, length, separator, 'A');
+}
+
 // Shared implementation for uint8_t and string hex formatting
 static std::string format_hex_pretty_uint8(const uint8_t *data, size_t length, char separator, bool show_length) {
   if (data == nullptr || length == 0)
diff --git a/esphome/core/helpers.h b/esphome/core/helpers.h
index fbd3aefd595..37534849d0b 100644
--- a/esphome/core/helpers.h
+++ b/esphome/core/helpers.h
@@ -677,12 +677,14 @@ constexpr uint8_t parse_hex_char(char c) {
   return 255;
 }
 
+/// Convert a nibble (0-15) to hex char with specified base ('a' for lowercase, 'A' for uppercase)
+inline char format_hex_char(uint8_t v, char base) { return v >= 10 ? base + (v - 10) : '0' + v; }
+
 /// Convert a nibble (0-15) to lowercase hex char
-inline char format_hex_char(uint8_t v) { return v >= 10 ? 'a' + (v - 10) : '0' + v; }
+inline char format_hex_char(uint8_t v) { return format_hex_char(v, 'a'); }
 
 /// Convert a nibble (0-15) to uppercase hex char (used for pretty printing)
-/// This always uses uppercase (A-F) for pretty/human-readable output
-inline char format_hex_pretty_char(uint8_t v) { return v >= 10 ? 'A' + (v - 10) : '0' + v; }
+inline char format_hex_pretty_char(uint8_t v) { return format_hex_char(v, 'A'); }
 
 /// Write int8 value to buffer without modulo operations.
 /// Buffer must have at least 4 bytes free. Returns pointer past last char written.